Why do humans have wisdom teeth if so many of them get removed soon after they appear?Wisdom teeth, the third molars in the back of our mouths, are so called because they normally appear in late teenage, early adulthood – the time in life we supposedly have learned some wisdom. But around 25% of people don’t develop all four. Of those that do emerge, it is not uncommon for them to appear at nasty angles, jutting into the tooth next door causing potentially dangerous infections and pain. Because of this, for decades many people have them surgically removed. Listener Khaleel was preparing to have his remaining wisdom teeth removed when he wrote to CrowdScience to ask about them. Given that they can seem to cause more harm than good, why has evolution resulted in these troublesome teeth? But many people have perfectly uneventful relationships with their wisdom teeth, so have we perhaps removed more than we needed to over the years?Anand Jagatia chews it over with the help of surgeons and dentists to try to extract the truth – why DO we have wisdom teeth?Featuring: Tanya M Smith, Professor in the Australian Research Centre for Human Evolution at Griffith University, Australia Patrick Magennis, Consultant Oral & Maxillofacial Surgeon at University Hospitals Aintree, Liverpool UK Verena Toedtling, Dentist and Specialist Oral Surgeon, UKPresented by Anand Jagatia Produced by Alex Mansfield

When the first person set the very first clock, how did they know what time to set it to? This question, from listener Chris in the UK, sends CrowdScience off on a quest into the history of timekeeping. From sundials to water clocks, from uneven hours to precision seconds determined by the vibration of an atom, we examine how we came to measure time. We visit possibly the oldest working mechanical clock in the world to discover how its time was originally set; and hear how the time we go by today is not quite the same as it was in the past. Will all this be enough to solve Chris' question, or has he stumped the team? Featuring:Ian Westworth, Clock Mechanic Dr. Chad Orzel, Associate Professor of Physics and Astronomy at Union College Anna Rolls, Curator of Clocks, Clockmakers’ Museum Peter, Guide, Salisbury Cathedral Dr. Jun Ye, Physicist at NIST (National Institutes of Standards and Technology) and The University of Colorado, Boulder.Presenter: Caroline Steel Producer: Margaret Sessa-Hawkins Editor: Cathy Edwards Production Co-ordinator: Jonathan Harris Studio Manager: Jackie Margerum (Photo:Stopwatch on red background. Credit: Martin Poole / Getty Images).

In 2011, CrowdScience listener Amanda survived the devastating earthquake in Christchurch, New Zealand.It arrived unannounced - as all earthquakes do - leaving her with no time to prepare a response. So Amanda wants to know whether science will ever be able to give us advance warning of quakes.To explore her question CrowdScience heads to New Zealand to meet listener Amanda, as well as the brains behind the country’s earthquake forecasting models. We dig in a field for thousand-year-old tectonic clues that could help us understand when the next earthquake might strike. But even if we could get a head start against a quake, would we respond in the right way?Please note: earthquake response advice varies by location. Please check local guidance and individual building procedures.Featuring:Nicola Litchfield, Principal Scientist in Paleoseismology at GNS, Wellington, New Zealand Matt Gerstenberger, Seismologist and leader of the National Seismic Hazard Model, GNS, Wellington, New Zealand Andy Howell, University of Canterbury, New Zealand Lauren Vinnell, Lecturer in Emergency Management at the Joint Centre for Disaster Research at Massey UniversityPresenter: Caroline Steel Producer: Emily Bird Editor: Cathy Edwards Production: Jonathan Harris, Jana Holesworth Sound Engineer: Steve Greenwood(Photo: Earthquake damage in Christchurch. Credit: John Crux Photography)

Have you ever been through a romantic break up, unable to shift the ex from your thoughts? You are, obviously, not alone…Listener Elkin, experienced just that. But rather than wallowing in self-pity, he sought out an explanation. Where better to get it, than from CrowdScience. Now, Alex Lathbridge is putting on his thinking cap to find out why we daydream?Presenter: Alex Lathbridge Producer: Harrison Lewis Editor: Martin Smith Production: Jonathan HarrisFeaturing:Giulia Poerio, Lecturer in Psychology, University of Sussex. Karina Christoff, Professor of Psychology, University of British Columbia. Eli Sommer, Israeli Professor of Clinical Psychology, University of Haifa. Sophie Forster, Reader in Psychology, University of Sussex(Photo: Man daydreaming surrounded by clouds. Credit: jacquesdurocher / Getty Images)

Presenter Marnie Chesterton and the team pit their wits against a multitude of mind-bending puzzles from an old TV gameshow - all in the name of answering a question from Antonia in Cyprus: how do we work out how clever someone is? Is IQ the best measure of cleverness? Why do we put such weight on academic performance? And where does emotional intelligence fit into it all? In the search for answers Marnie and the team are locked in rooms to battle mental, physical, mystery and skill-based challenges, all against the clock. Unpicking their efforts in the studio are a global team of cleverness researchers: Dr Stuart Ritchie from Kings College London, Prof Sophie von Stumm from York University and Dr Alex Burgoyne from Georgia Institute of Technology in the US. They are challenged to face the toughest questions in their field: Why do men and women tend to perform differently in these tests? Is our smartness in our genes? And what about the Flynn Effect – where IQs appear to have risen, decade after decade, around the world. Producer/presenter: Marnie Chesterton Editor: Richard Collings Production co-ordinator: Jonathan Harris (Photo Man doing puzzle. Credit: Getty Images)

What evidence is there for a semi-aquatic period in human evolutionary history? That’s the question that’s been bothering listener Dave in Thailand. He thinks our lack of hair and love of water might indicate that, at some point, we were more water-based than we are now. But what does science have to say on the matter? The theory that our ape ancestors returned to the water for a phase in our evolutionary history is a controversial idea that most scientists disagree with. Anand Jagatia chats to Dr Melissa Ilardo, assistant professor at the University of Utah, about our dive reflex - a physiological response we display when submerged underwater, which helps direct oxygen towards vital organs. But this is not a response that is unique to humans - it is found in all mammals. Experts say it developed long before all apes split off in the evolutionary tree. To find out more about the theory itself Anand hears from John Langdon, emeritus professor at the University of Indianapolis. He explains why the aquatic ape theory is not generally accepted by anthropologists, what the fossil record can tell us about our evolutionary path and why evolution is much more complex than the aquatic ape hypothesis suggests. While there may be little evidence of a semi-aquatic period in our evolutionary past, there are some communities around the world that have adapted to utilising their watery environments in more recent evolutionary history. Anand speaks to Dr Nicole Smith-Guzman at the Smithsonian Tropical Research Institute who has found evidence that ancient populations in Panama were habitually diving in the sea for shells and seafood. She explains how she can piece together evidence from different sources to detect the activity of ancient populations. And Dr Melissa Ilardo explains how evolutionary pressure can cause physical changes in isolated communities, as our bodies ultimately adapt to help us thrive in more watery environments. Producer: Hannah Fisher Presenter: Anand Jagatia Editor: Richard Collings Production co-ordinator: Jonathan Harris Sound engineer: Jackie Margerum(Photo: Woman swimming underwater. Credit: Petrelos/Getty Images)

Our question this week comes from a father and his two young boys. They want to know whether it’s possible to plant enough trees to soak up all the extra carbon we are putting into the atmosphere? The quest to find answers takes us to a remote re-forestation project in the Carpathian Mountains in Romania which could be a model for other projects looking to tackle the climate crisis through reforestation. We speak to experts to find out how much tree planting and reforestation can do in helping combat the climate crisis. Presenter: Caroline Steel Producer: Margaret Sessa-Hawkins Editor: Richard Collings

Moise pollution from vehicles in the public space has a huge impact on human health. But as the world switches to quieter electric-powered means of transport there’s a debate about whether we will actually see any noticeable improvement to our quality of life. Discovering more than just engineering solutions to the problem, CrowdScience visits one of the world’s loudest cities, Mumbai in India. It’s a place where noise has become a way of life. But is that all about to change? Presenter: Alex Lathbridge Producer: Richard Walker Production Co-ordinator: Jonathan Harris Editor: Richard Collings

Welcome to Part 2 of our year-end extravaganza and the final episode of 2023! We’ve had a brilliant year hunting down the answers to your science questions - on everything from food and phobias to friction and flying - and in this episode presenter Anand Jagatia is revisiting some of the best stories we covered. We’re bringing you some extra juicy bonus content that we couldn’t fit in to those shows first time round. Hannah Fisher joins Anand to revisit an episode she produced about the microbiome, the community of tiny organisms living both on and inside us. During that show Hannah took presenter Caroline Steel to a microbiome museum in the Netherlands called Micropia. And one thing from Micropia that never got aired was the kiss-o-meter, a device that measures how many microbes you exchange when you kiss! Micropia curator Jasper Buikx explains the science behind the kiss-o-meter, and then Caroline Steel tries it for herself! Microbes aren’t just living on and in humans and animals - they’re pretty much everywhere in our environment. And to illustrate this CrowdScience producer Marijke Peters brings Anand a bonus interview with a professional surfer who’s also a bioscientist. Cliff Kapono undertook a scientific project travelling around the world to take microbiome samples from surfers in different countries. He discovered a fascinating global connection. Surfers are linked together by microbes on their skin that they get from the water around them. Intriguingly, he describes how this might affect our perception of who we are as humans. Caroline Steel updates us on an interview she did with indigenous Australian astronomer Peter Swanton. Peter appeared on CrowdScience telling an ancient Australian folktale about a man who sacrificed himself to save his brother. The story, which has been handed down through several generations, provides possible evidence for an early observation of a supernova. You can hear that story in the episode “Why is the sun at the centre?” Today we hear two extra stories that originally got cut from the broadcast due to time constraints. They are beautiful and poignant tales that reveal the depth of indigenous scientific achievement and the extraordinary significance of the night sky. Presenter: Anand Jagatia Producer: Phil Sansom Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Managers: Tim Heffer and Cath McGee Featuring: Jasper Buikx, scientific curator & spokesperson, ARTIS-Micropia Prof. Cliff Kapono, surfer & molecular bioscientist, School of Ocean Futures at Arizona State University Peter Swanton, indigenous research associate, Australian National University

Welcome to Part 1 of CrowdScience’s year-end extravaganza! It’s an extra-festive episode this week. For those who celebrate it, Christmas is the perfect time to pause and look back at the year just gone. Here on CrowdScience we’ve had a great 2023: we answered dozens of listener questions, ranging from climbing plants and ostriches to panic attacks and the weight of the internet. This week presenter Anand Jagatia magically appears with a Santa’s sack full of special features. We’re catching up with some of our favourite guests from the past year and answering some of the extra questions that we never got the chance to cover. First up we hear from presenter Tim Clare who we first heard in the episode “Why do some people have panic attacks?” He takes Anand through his new book – it's about board games: why we play them, how they’ve existed throughout history and what he’s learned about himself in the process of writing it. Then it’s time for a bonus question. The CrowdScience team often get questions about noise pollution. One listener got in touch to ask whether the transition to electric vehicles will reduce this noise. Acoustic scientist Kurt Fristrup and epidemiologist Erica Walker give their perspectives on this question, and how sound and noise can sometimes be very different things. CrowdScience listener Marie - who originally starred in an episode about why she doesn’t have any sense of time - returns. Since the programme she has been speaking to psychologists about her problem and tells Anand what more she’s learnt. We received another bonus question after a show in 2023 about AI: why can’t artificial intelligence be designed to explain it’s decisions? Producer Phil returns to data scientist Briana Brownell from the original episode to ask her why AI decision making is so very complex. Finally, as it’s the season for holiday music, we’re asking what makes the genre so distinctive? Composer Jane Watkins - who originally created the sound of a panic attack for a CrowdScience episode - brings in her musical keyboard to demonstrate what makes a Christmas song so specifically ‘a Christmas song’. It’s all topped-off with the premiere of a happy and heart-warming song performed by the CrowdScience Christmas Choir – a little gift for our loyal listeners. Presenter: Anand Jagatia Producer: Phil Sansom Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Managers: Tim Heffer and Cath McGhee Featuring: Tim Clare, author/poet/podcaster Dr. Kurt Fristrup, acoustic scientist, Colorado State University Prof. Erica Walker, RGSS Assistant Professor of Epidemiology, Brown University School of Public Health Marie Bergholtz Briana Brownell, data scientist Jane Watkins, composer

Seeds are crucial to human existence – we eat them, we grow them and then we eat what they become. But what is a seed and how come it can sit there doing nothing for ages and then suddenly, when the conditions are right, burst into a plant?That’s what CrowdScience listener Anke has been wondering. She runs an aquaponic salad farm near Stockholm in Sweden and she germinates thousands of seeds every week. With a bit of moisture and light, seeds that have been dormant for months can become leafy greens in just a few weeks. So are seeds alive, are they on some kind of life support, or is something else going on?Presenter Caroline Steel sets off to Sweden to meet Anke, before heading for the Nordgen seed bank near Malmö. There she discovers how seeds being stored for future generations are tested for viability, and wonders what’s going on inside a seed that allows it to remain asleep before suddenly coming to life. How does a seed decide that the time is right?We hear about one of the world’s longest running science experiments - a real-life treasure hunt that takes place every twenty years in Michigan, USA. Plant biologists tramp through the snow looking for bottles of seeds that were buried nearly a century and a half ago. Once found they try to germinate them. What superpowers does a seed need to be able to last that long?Caroline also meets the woman who tried to grow date seeds that had been discarded at the palace of Herod the Great 2000 years ago, and ended up with previously extinct trees that produce delicious fruit. Surely a seed can’t have been alive for that long. Or can it?Contributors:Anke Johanna van Lenteren, Johannas Stadsodlingar, Sweden Johan Axelsson, Nordic Genetic Resource Center, Sweden Prof George Bassel, University of Warwick, UK Dr Grace Fleming, Michigan State University, USA Dr Sarah Sallon, Hadassah Medical Center, IsraelPresenter: Caroline Steel Producer: Ben Motley Editor: Richard Collings Production Coordinator: Jonathan Harris(Photo: Hands holding spinach seeds. Credit: Vince Streano / Getty Images)

If, like this week’s Crowdscience listener Lili, you enjoy working out in the gym, you may have wondered where your fat disappears to when you exercise? The short answer is that we convert it to energy that powers a whole range of physical processes -- from breathing to walking as well as lying down and doing nothing. But the science behind energy expenditure is a little more complicated than that. Presenter Anand Jagatia jumps on an exercise bike to have his metabolism measured and learns that he may be relying on an entirely different source of fuel as he works up a sweat. Is all that hard work worth the effort it involves? Recent research suggests there's a limit to the number of calories humans can burn and that engaging in physical activity isn’t always a sure-fire way to keep trim. So if working out isn't the best way to lose weight, how about harnessing our own fat to tackle the complications of obesity? It used to be thought brown fat was exclusive to babies (and bears) but we now know adults have some of it too. Anand discovers that it appears to play a vital role in combatting a range of chronic diseases including hypertension and diabetes. Presenter: Anand Jagatia Producer: Marijke Peters Editor: Richard Collings Production co-ordinator: Jonathan Harris (Photo: Person squeezing their tummy. Credit: Getty Images).

*Warning* This episode includes references to suicide. When listener Ben heard about a Kenyan “starvation cult” in the news, he wondered whether the members of this group had been brainwashed. Is it possible to control someone’s mind? In this episode presenter Caroline Steel learns how easily people can be influenced. She hears what it’s like to be part of a cult, and gets to the bottom of a decades-long debate: does brainwashing exist? And, if so, how does it work? Presenter: Caroline Steel Producer: Florian Bohr Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Managers: Donald McDonald and Emma Harth Featuring: Anthony Pratkanis, Emeritus Professor of Psychology, University of California, Santa Cruz Alexandra Stein, Honorary Research Fellow, University of Sussex Eileen Barker, Professor Emeritus of Sociology, London School of Economics (Image: Washing a brain. Credit: Cemile Bingol / Getty Images).

CrowdScience listener Michael wants to know whether the brain responds differently if we listen to books instead of reading them. Do we retain information in the same way? And is there a difference between fiction and non-fiction? Anand Jagatia finds out whether curling up with a good book is better than putting on his headphones. Contributors: Professor Fatma Deniz, Technical University of Berlin Professor Naomi Baron, American University, Washington DC Professor Patrick Nunn, University of Sunshine Coast, Queensland The Guesthouse Storytellers Presenter: Anand Jagatia Producer: Jo Glanville Editor: Richard Collings Production Co-ordinator: Jonathan Harrison Studio manager: Andrew Garratt (Photo: Senior man wearing headphones listening to an audiobook. Credit: pixdeluxe / Getty Images.)

Lying is something all humans do. We find it in every culture around the world. It’s in the world of work, in our relationships and online. It’s all pervasive and hard to escape. Our question this week is from listener Anthony from Cambodia. He asked us to find out why we lie, and wants to know how conscious we are of the lies that we tell? CrowdScience’s Caroline Steel is in the hot seat, on a journey where she will attempt to untangle the complex story behind lying. It’s a subject scientists and psychologists have been studying for a long time. It’s also something writers, philosophers and theologists have been interpreting for thousands of years. But we’re only now really starting to get to grips with how it works as a human behaviour. There are lies in our folklore, lies in the media and also lies in everyday conversation. It’s something we’ve all had to learn to navigate at some point in our lives. In this episode the CrowdScience team unravels the mysteries surrounding the behaviour and the art of lying. Our journey will take us to meet the world’s ‘second best liar’, an award she picked up at West Virginia’s Liar Contest. We’ll also meet a comedian who’s proud of the down-to-earth plain honesty of Dutch people. An academic who has studied thousands of children’s brains will explain when we first start learning to lie. And we’ll hear about new research using magnetic resonance imaging, commonly known as MRI scans, which is helping to show how the more we actually lie, the less our brain reacts telling us not to. Caroline looks at how lying changes from culture to culture. Do we really all lie? And do we lie in the same way? The surprising and intriguing answer is found in how early it develops in us as a human behaviour. And how it’s hard-wired into our DNA. Contributors: Prof Kang Lee, Professor in Applied Psychology and Human Development at Ontario Institute for Studies in Education, University of Toronto Prof Tali Sharot, Professor of Cognitive Neuroscience at University College London Ian Leslie, journalist and author of ‘Born Liars’ Ariana Kincaid, Champion Liar at West Virginia Liars Contest Derek Scott Mitchell, actor and comedian | @letsdoubledutch on Instagram Readings by Kitty O'Sullivan Presenter: Caroline Steel Producer: Robbie Wojciechowski Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Managers: Emma Harth, Donald MacDonald, Andrew Garratt (Photo: Young Businessman Interviews for new job. Credit: Andrew Rich/ Getty Images)

Our planet is quickly approaching 1.5 degrees Celsius of warming (2.7 degrees Fahrenheit). Scientists say we might cross this milestone in just six years. Listener Julian wants to know what life will look like on the other side of that threshold. With the help of climate scientists, the BBC’s Anand Jagatia dives into the worlds of virtual climate models. From heatwaves to higher humidity indices to extreme precipitation and drought, he gets a picture of what's to come. We also venture to places that are warming both faster and more slowly than the global average. In a remote village in Alaska residents are already dealing with life-changing permafrost thaw and ground that's melting beneath their feet. Permafrost expert Sue Natali tells us what this unexpected thawing ground means for the planet as it releases carbon and methane we weren't necessarily counting on. In Indian cities, temperatures were already high, but they're not rising as quickly as climate scientists had initially predicted. We hear why this is and why it might be a big problem in the not- too-distant future. Anand also speaks to television series writer Dorothy Fortenberry about how science informed plotlines in her new show Extrapolations. This episode is not just about what climate change will bring -- but what it will feel like. Presenter: Anand Jagatia Producer: Sam Baker Reporters: Sunni Bean & Chhavi Sachdev Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Manager: Tim Heffer Featuring: Dorothy Fortenberry, Extrapolations, Apple TV Tom Matthews, Department of Geography, King's College London Sue Natali, Woodwell Climate Research Center Morris Alexie, Tribal Liaison, Alaska Native village of Nunapicuaq (Nunapitchuk) Rakesh Kumar, India’s Council of Scientific and Industrial Research (Photo: Two children look out at floating sea ice. Credit: StutterStockX / Getty Images)

“You are what you eat” is a well-known saying. But is it really true? That’s what we explore in this week’s CrowdScience thanks to a question from listener Claire from Australia. We each have trillions of tiny microbes and bacteria inside our bodies, living in our mouths, skin, ears and even in our eyes. Each community of microbes and bacteria is known as a microbiome. The most populous of these is in our gut, with hundreds of trillions of organisms and bacteria helping digest the food we eat. Our gut microbiome is affected by lots of things but mainly by our diet. With our gut microbiome forming such a massive part of our insides, people have long suspected that what we eat impacts how we feel. Presenter Caroline Steel investigates. She speaks to a professor of Psychiatry, Jane Foster, to find out how interconnected our microbiome and our brain really are. Professor Foster also explains the different ways in which our microbiome and brain communicate. Do we really know what role diet plays in mental health? Consultant psychiatrist Professor David Veale provides more detail. And at a café with a rather interesting menu, Caroline samples some of the food available as occupational therapist Joel Oliver explains how important food can be as part of mental health treatment. This begs the question: if our microbiome really does influence our mental health, can we harness the power of microbes to potentially find new treatments to help our mental health? Dr Najaf Amin tells us about her research identifying the link between specific microbes and depression. Producer: Hannah Fisher Presenter: Caroline Steel Editor: Richard Collings Production Coordinator: Jonathan Harris Studio Manager: Bob Nettles (Photo: Young hipster man eating salad. Credit: Tara Moore / Getty Images)

Why are some animals cute, cuddly, adorable – and some are slimy, creepy and downright weird? This edition of Crowdscience, recorded in front of a live audience, comes to you directly from the world-famous Green Man Festival in Bannau Brycheiniog National Park in Cymru (Wales). The programme recording was powered entirely by hydrogen. Our inbox has been bursting at the seams with questions about creepy crawlies, deep sea beasties, cheeky monkeys, endangered species and animals of all shapes and sizes. So, we rounded up a panel of experts to get some answers! Surrounded by 25,000 people trudging merrily through the mud, pelted with torrential rain, underscored by the warm hum of revelry, the BBC’s Marnie Chesterton speaks with Dr David Jones from the Natural History Museum, an expert on creepy crawlies and someone who spends a considerable amount of time thinking about earthworms, ants, and termites. Also joining us is Jess Savage, a researcher from the Institute of Zoology in London who’s an expert on ocean-dwelling animals and the impact of plastic pollution. Finally, we have Simon Watt, a biologist, comedian and founder of the Ugly Animal Preservation Society. Join us for this very special edition of Crowdscience, in partnership with Green Man Festival, where we bring the experts closer to you than ever before. Presenter: Marnie Chesterton Producer: Emily Bird Editor: Richard Collings Technical Producer: Mike Cox Studio Manager: Jackie Margerum Production Co-ordinator: Jonathan Harris (Photo: Marnie and guests. Credit: Jonathan Harris.)

Salmon farming is a massive global industry. Just off the coasts of countries like Norway or Chile, hundreds of millions of these fish swim around inside big ocean nets. They provide crucial proteins and fatty acids to many people’s diets, but are they more or less healthy than their wild cousins? That’s what CrowdScience listener Jodie wants to know. For presenter Marnie Chesterton, answering this question means visiting a Scottish salmon farm and collecting dispatches from the ocean around Alaska; it means a closer look at what the salmon themselves are eating; and it means moving beyond nutrition to explore the health of the environment as well. What problems do salmon farms solve, what problems do they cause, and could moving onto land be the future for this field? (Photo: Atlantic Salmon jumping out of the water. Credit: Kevin Wells)

CrowdScience listener Kristine from Wisconsin in the USA wants to know why herbs and spices taste so good to so many of us. She’s intrigued to know if there's evidence that herbs and spices can keep us healthy. Anand Jagatia visits the historic naval city of Portsmouth in the UK, where exotic spices from around the world were first brought in from the East Asia more than 600 years ago. He’s on a journey to find out why many of us think spices are delicious. But are there also nutritional benefits to seasoning our food with them? Anand asks what science or studies are there to show that eating herbs and spices can be beneficial for our health? Presenter: Anand Jagatia Producer: Joanna Hall Assistant Producer: Jonathan Harris Editor: Richard Collings Studio Technicians: Bob Nettles & Steve Greenwood Contributors: Prof. Lindell Bromham, evolutionary biologist, Australian National University Dr. Kanchan Koya, Molecular Biologist and founder of the Spice Spice Baby website Dr. Beronda L. Montgomery, plant biologist and Dean at Grinnell College, Iowa, USA Dr. Lorenzo Stafford an olfactory researcher, Department of Psychology, University of Portsmouth, UK (Photo: A couple stand at a spice shop. Credit: Thomas Barwick / Getty Images)

Humans have an outsized impact on the planet: we’ve wreaked havoc on countless ecosystems and one study estimates only 3% of land on Earth remains untouched by our influence. CrowdScience listener Teri has witnessed the harmful effects of development on natural habitats near her home, and wonders whether we can ever function as part of a healthy ecosystem. We look for answers in Teri’s home state, California. Humans have lived here for over 10,000 years and its first inhabitants formed a connection to their landscape unlike the exploitative approach of many later settlers. Today, the beliefs and traditions of the Karuk Tribe of northern California still emphasise a symbiotic relationship with nature, seeing plants and animals as their relations. Over the past couple of centuries much of the Karuk’s land has been degraded by mining, the timber industry and the outlawing of traditional burning practices. Tribal members show us how they’re working to try to restore ecological balance. As for the rest of humanity: can we rein in our destructive relationship to nature; or even have a beneficial effect on our local ecosystems? Contributors: Kathy McCovey - Karuk Tribe member and cultural practitioner Dr Steward Pickett - Ecologist, Cary Institute of Ecosystem Studies Bill Tripp - Karuk Tribe member and Director of Natural Resources and Environmental Policy, Karuk Tribe Department of Natural Resources Dr Frank Kanawha Lake - US Forest Service Research Ecologist and Tribal Liaison Will Harling - Co-lead, Western Klamath Restoration Partnership Presenter: Caroline Steel Producer: Cathy Edwards Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Manager: Giles Aspen & Steve Greenwood (Image: Huckleberries and tanoak acorns gathered near a burn site. Credit: Stormy Staats)

It's pretty obvious to each of us that we are conscious, as we go about our days and feel the experience of just ‘being ourselves'. But how do we know that someone else is conscious? It’s something we lose during dreamless sleep, under anaesthesia or in a coma. But what exactly is consciousness? On the one hand, it’s pretty obvious - it’s what we all feel as we go about our daily lives. It's the experience of 'being you'. On the other hand, it gets pretty tricky when we try to pin down the science of it all. How do we know that someone (or something) else is conscious? CrowdScience listener Sylvester was wondering about this and he got in touch with a few questions on the subject. What is the relationship between our consciousness and reality? Is it all just a hallucination? When does it start and stop? Does consciousness reside in a particular part of the brain? Host Marnie Chesterton sets out to tackle this elusive but utterly fundamental quality of life and sees how researchers are attempting to conceptualise and study it. In the relatively young field of consciousness multiple theories have emerged. A new way of testing them - an adversarial collaboration - is offering a novel approach to not just consciousness research but science more broadly. We visit one lab in Frankfurt that's running experiments for the most recent adversarial collaboration and trying to test two theories of consciousness – Global Neuronal Workspace Theory (GNW) and Integrated Information Theory (IIT) – against each other. Looking at these and other concepts of consciousness like Qualia, Marnie tries to understand this central tenet of our human experience that, in many ways, remains one of the great mysteries of science. Presenter: Marnie Chesterton Producer: Sam Baker Editor: Richard Collings Production Coordinator: Jonathan Harris Studio Manager: Sarah Hockley Featuring: Anil Seth, Sussex Centre for Consciousness Science, University of Sussex in Brighton, England Lucia Melloni, Max Planck for Empirical Aesthetics in Frankfurt, New York University & Project Lead for COGITATE Nao Tsuchiya, Monash Data Futures Institute, Turner Institute for Brain & Mental Health, Monash University (Image: Active Human Brain. Credit: PM Images / Getty Images)

Philosophers have long pondered the concept of a brain in a jar, hooked up to a simulated world. Though this has largely remained a thought experiment, CrowdScience listener JP wants to know if it might become reality in the not-too-distant future, with advances in stem cell research. In the two decades since stem cell research began, scientists have learned how to use these cells to create the myriad of cell types in our bodies, including those in our brains, offering researchers ways to study neurological injuries and neurodegenerative disorders. Some labs have actually started 3D printing stem cells into sections of brain tissue in order to study specific interactions in the brain. Human brain organoids offer another way to study brain development and diseases from autism to the Zika virus. So, might stem cell research one day lead to a fully-grown human brain, or is that resolutely in the realm of science fiction? If something resembling our brains is on the horizon, is there any chance that it could actually become conscious? And how would we even know if it was? Host Marnie Chesterton takes a peek inside the human brain and speaks with leading scientists in the field, including a philosopher and ethicist who talks about the benefits – and potential pitfalls – of growing human brain models. Along the way, we'll pull apart the science from what still remains (at least for now) fiction. Presenter: Marnie Chesterton Producer: Sam Baker Assistant Producer: Jonathan Blackwell Editor: Richard Collings Production Coordinator: Jonathan Harris Studio Manager: Jackie Margerum (Image: Brain in a jar. Credit: Mike Kemp / Getty Images)

Everyone has fears – but what makes a fear become a phobia? Why are some people scared of spiders (arachnophobia), buttons (koumpounophobia), or the colour yellow (xanthophobia)? Or why are others are scared of situations, like small spaces (claustrophobia), empty rooms (kenophobia) or heights (acrophobia)? This is a question which has been bothering Crowdscience listener Scott, who has a phobia of bridges. He gets anxious and panicky when driving over bridges and is scared he’ll lose control of the car. It’s also a question that struck a chord with presenter Caroline Steel. She is claustrophobic, particularly in lifts, steering clear of them at all costs and even once climbing nine flights of stairs in crutches to avoid using the lift. But where do these phobias come from and why do some people have them and not others? To investigate, Caroline speaks to experts to discover where phobias come from, why we have them and how they develop. And she visits a psychologist to learn about different types of treatment for phobias, and to receive treatment herself in the hope that one day, maybe she’ll be able to take the lift instead of the stairs. Contributors: Professor Paul Salkovskis, Director, Oxford Centre for Psychological Health, UK Professor Ekaterina Likhtik, Associate Professor in Biological Sciences at Hunter College, CUNY, USA Dr Andras Zsido, Assistant Professor at the University of Pécs, Hungary Presenter: Caroline Steel Producer: Hannah Fisher Editor: Richard Collings Production Co-ordinator: Jonathan Harris (Image: Person sitting on high up bridge. Credit: ljubaphoto / Getty Images)

CrowdScience listener Leo gets stressed when his young children start screaming at the same time in the middle of the night. He wants to know why we haven’t evolved to deal with the stress more effectively. The challenges of bringing up a family are nothing new and we don’t face the same dangers as our ancestors, so why do we still react as if it’s a life-threatening emergency? Caroline Steel finds out what stress is for, what it does to us and whether we have in fact evolved to manage it. Contributors: Tashfia Ahmed, biomedical engineer, post-doctoral researcher, City University, London Anne-Kathrin Gellner, neurologist and psychiatrist, Bonn University James Rilling, anthropologist and neuroscientist, Department of Psychology and Department of Psychiatry and Behavioural Sciences, Emory University Gunter Wagner, evolutionary biologist, Vienna University Presenter: Caroline Steel Producer: Jo Glanville Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Manager: Jackie Margerum

Many of us are worried about the environment, but the aim of living in a truly sustainable way is hard to pin down. Do we all need to stop buying things? Is it down to governments to make the changes for us? Is there somewhere in the world painting a picture of the end goal? It’s a question that has bothered CrowdScience listener Cate for 20 years! She’s worried we’re not doing enough for the environment and just wants a clear scenario of what it might look like to live sustainably, in a way that could work for all eight billion of us on the planet. It’s a big question, so this week presenter Caroline Steel has teamed up with her friend and colleague Graihagh Jackson from The Climate Question podcast to answer it. They head to the remote Danish island of Bornholm in the Baltic Sea, which is aiming to go carbon neutral by 2025 and zero waste by 2032. How are they going about it and could this be replicated elsewhere? We visit a ground-breaking project turning nappies into compost, meet a glassblower making tableware out of wasted insulin vials, and find out how pig waste can power homes. This edition of CrowdScience hones in on Bornholm’s zero waste goal. Will the island make it? Listen to The Climate Question’s look at the island’s quest to go carbon neutral here: BBC World Service - The Climate Question, Going carbon neutral - lessons from Denmark - www.bbc.co.uk/programmes/w3ct5bkg (Available from 3rd September) Presenters: Caroline Steel and Graihagh Jackson Producer: Sophie Eastaugh Editor: Richard Collings Production Coordinator: Jonathan Harris (Image: Dr David Christensen, Project Manager at BOFA, Bornholm’s waste authority with presenter Caroline Steel in front of a giant mound of waste bound for the island’s incinerator. The incinerator will be shut down in 2032 when the island aims to be zero waste. Credit: Sophie Eastaugh)

For hundreds of millions of years insects controlled the skies. Before birds, bats and pterodactyls, insects were the only creatures that had evolved the ability to fly: a miracle of physics and physiology requiring their bodies to act in coordinated ballet. This week three separate CrowdScience listeners have been asking questions about the flight of butterflies and moths. How do they move so erratically, yet land so precisely? What makes such tiny insects such accurate flyers? Presenter Anand Jagatia -- not the biggest fan of either butterflies or moths -- visits Butterfly Paradise at London Zoo to meet keeper Mark Tansley. Anand tries to get over his aversion by immersing himself in fluttering creatures. He then meets insect flight expert Sanjay Sane to learn the hidden mechanics behind their aeronautical skills: the vortexes of air generated by their wings and the complex muscle architecture inside their torsos. Next, aerospace engineer Amy Lang explains how the scales on their wings reduce air resistance by clever manipulation of the air and how this function trades off against other uses of the scales: for colour, for keeping dry, and much more. All of these abilities are put to the test during the incredible global migrations that some butterflies undertake. Gerard Talavera tells Anand how he turned previous thinking about butterfly migration across Africa on its head. Presenter: Anand Jagatia Producer: Phil Sansom Voiceover: Kitty O’Sullivan Production Coordinator: Jonathan Harris Editor: Richard Collings (Photo: Crowdscience presenter Anand Jagatia crouches next to a butterfly. Credit: Phil Sansom)

How do you think about the internet? What does the word conjuror up? Maybe a cloud? Or the flashing router in the corner of your front room? Or this magic power that connects over 5 billion people on all the continents of this planet? Most of us don’t think of it at all, beyond whether we can connect our phones to it. CrowdScience listener Simon has been thinking and wants to know how much it weighs. Which means trying to work out what counts as the internet. If it is purely the electrons that form those tikitok videos and cat memes, then you might be surprised to hear that you could lift of the internet with 1 finger. But presenters Caroline Steel and Marnie Chesterton argue that there might be more, which sends them on a journey. They meet Andrew Blum, the author of the book Tubes – Behind the Scenes at the Internet, about his journey to trace the physical internet. And enlist vital help from cable-loving analyst Lane Burdette at Telegeography, who maps the internet. To find those cables under the oceans, they travel to Porthcurno, once an uninhabited valley in rural Cornwall, now home to the Museum of Global Communications thanks to its status as a hub in the modern map of worldwide communications. With the museum’s Susan Heritage-Tilley, they compare original telegraph cables and modern fibre optics. The team also head to a remote Canadian post office, so correspondent Meral Jamal can intercept folk picking up their satellite internet receivers, and ask to weigh them. A seemingly innocuous question becomes the quest for everything that connects us, and its weight! Producer: Marnie Chesterton Presenter: Marnie Chesterton & Caroline Steel Editor: Richard Collings Production Coordinator: Jonathan Harris (Image: Scales with data worlds and symbols interspersed throughout. Credit: Getty Images)

Dogs have been our best animal buddy for thousands of years. They’ve helped us out in countless ways from hunting alongside us to guiding us as service dogs. Talk to any pet owner and they’ll tell you how much joy their dog brings them. But you’ll also probably hear about vets bills, muddy footprints, or chewed up slippers. There are plenty of claims about the ways in which dogs might benefit our physical and mental health -- but how strong is the evidence? This week on CrowdScience, listeners Jason and Finn in Guernsey want to know if there’s any real evidence that our furry friends can benefit our health and wellbeing. Join Anand Jagatia as he enlists the help of his own pup, Stella, to explore the evidence. He uncovers the profound effects that service dogs can have on the mental health of military veterans in the US. Anand ponders the strangely unique relationship between humans and dogs and we learn about the surprising ways that about growing up with a pet dog can impact your health. Presenter: Anand Jagatia Producer: Emily Bird Editor: Richard Collings Studio Engineer: Donald MacDonald Production coordinator: Jonathan Harris, Elliott Prince Contributors: Dr Kerri Rodriguez Professor Tove Fall Professor Hal Herzog (Photo: Jack Russell leaping into the air trying to catch a ball. Credit: Brighton Dog Photography/Getty Images)

Imagine spending six months of every year living in total shade. That’s what life is like for residents of the Norwegian town of Rjukan, set so low in a valley that they see no direct sunshine at all from October to March. Marnie Chesterton heads there to hear about an ingenious solution: giant mirrors that beam rays down into the town square, where locals gather to feel the reflected heat. The man behind the project was motivated by a need for winter sun – but how much difference does it really make to our health and happiness? That’s the question posed by this week’s CrowdScience listener Michael, who has noticed living in the rainy Australian city of Melbourne is taking its toll. Many pensioners claim sunshine relieves achiness as well as conditions like arthritis but one of the biggest scientific studies found temperature has no real impact on reported pain levels, while factors like air pressure and humidity may play a role. When it comes to our mood, it seems that spending time outside is more important than feeling the heat. The optimum temperature for wellbeing is around a cool 19 degrees centigrade, while excessive warm weather has been linked to an increase in violence and crime. You can watch a visualisation of this episode on YouTube: Is the 'sunshine cure' a real thing? - CrowdScience, BBC World Service podcast - YouTube Producer: Marijke Peters Presenter: Marnie Chesterton Editor: Richard Collings Production co-ordinator: Jonathan Harris Contributors: Dr Anna Beukenhorst, University of Manchester Professor Oscar Ybarra, University of Illinois Professor Solomon Hsiang, University of California, Berkeley Martin Andersen, artist (Photo: Young woman enjoying sunset. Credit: Muriel De Seze/Getty Images)

Imagine spending six months of every year living in total shade. That’s what life is like for residents of the Norwegian town of Rjukan, set so low in a valley that they see no direct sunshine at all from October to March. Marnie Chesterton heads there to hear about an ingenious solution: giant mirrors that beam rays down into the town square, where locals gather to feel the reflected heat. The man behind the project was motivated by a need for winter sun – but how much difference does it really make to our health and happiness? That’s the question posed by this week’s CrowdScience listener Michael, who has noticed living in the rainy Australian city of Melbourne is taking its toll. Many pensioners claim sunshine relieves achiness as well as conditions like arthritis but one of the biggest scientific studies found temperature actually has no impact on reported pain levels, while factors like air pressure and humidity may play a role. When it comes to our mood, it seems that spending time outside is more important than feeling the heat and the optimum temperature for wellbeing is around a cool 19 degrees centigrade, while excessive warm weather has been linked to an increase in violence and crime. Contributors: Dr Anna Beukenhorst, University of Manchester Professor Oscar Ybarra, University of Illinois Professor Solomon Hsiang, University of California, Berkeley Martin Andersen, artist (Image: Man with smoke coming out of ears. Credit: Getty Images)

CrowdScience investigates the link between music and emotion to try and understand why certain songs can have such a profound impact on our mood. From breakup songs to upbeat holiday hits, many of us have made playlists that reflect how we feel, whether that’s down in the dumps or high as a kite. This week CrowdScience investigates the link between music and emotion to try and understand why certain songs can have such a profound impact on our mood. Presenter Anand Jagatia is surprised to learn that newborn babies are more likely to fall asleep when listening to fast tempo happy tunes than soothing sad lullabies, which may be because they’re attuned to multiple auditory stimuli after months in the womb. But later in life we actually seek out sad songs to make us feel better. The so-called ‘sadness paradox’ has been studied for many centuries. But what is it about melancholy music that might be good for us? Some scientists believe more empathetic people enjoy listening to these types of tune because they elicit a feeling of compassion towards others, which can be rewarding. A film composer tells us how scoring suspense isn’t simply about minor or major chords, or even what instruments you use – it all comes down to keeping the audience guessing about what’s coming next. (Photo: young woman listening to headphones looking sad. Credit: Getty Images) Presenter: Anand Jagatia Producer: Marijke Peters Production co-ordinator: Jonathan Harris Editor: Richard Collings Studio Technician: Phil Lander Contributors: Alex Heffes Professor Stefan Koelsch Dr Emese Nagy Associate Professor Jonna Vuoskoski Dr Scott Bannister

“I’m bored!” We can all relate to the uncomfortable - and at times unbearable - feeling of boredom. But what is it? Why does it happen? And could this frustrating, thumb-twiddling experience actually serve some evolutionary purpose? CrowdScience listener Brian started wondering this over a particularly uninspiring bowl of washing up and it’s ended with presenter Marnie Chesterton going on a blessedly un-boring tour through the science and psychology of tedium. She finds out why some people are more affected than others, why boredom is the key to discovery and innovation and how we can all start improving our lives by embracing those mind-numbing moments. (Photo: Bored kids on a park bench. Credit: Getty Images) Presenter: Marnie Chesterton Producer: Samara Linton Production co-ordinator: Jonathan Harris Editor: Richard Collings Contributors: Professor James Danckert, University of Waterloo, Canada Dr Elizabeth Weybright, Washington State University Dr Christian Chan, Hong Kong University Annie Runkel, University of Dundee

Why are some people left-handed? Why are some people right-footed? Why do some write with their right and throw a ball with their left? What does this all have to do with our brains? Why is it hard for some people to tell left from right? And what about animals? Can they be left-flippered, or finned, or southpawed? That's what a few CrowdScience listeners want to know, and we've got an expert panel on left, right and everything in between to help answer your questions. From genetics to culture, host Caroline Steel works to unpack what's known and what's still unknown about handedness. David Carey from Bangor University helps Caroline better understand her own mixed-handedness through a series of simple tests and shares some insights into what role handedness (and footedness) plays in the world of sports. Neuropsychologist Marietta Papadatou-Pastou from National and Kapodistrian University of Athens helps break down the numbers on left v. right-handedness and its cultural influences. To better understand the genetics and evolution of handedness, we hear from Sebastian Ocklenburg from Medical School Hamburg, who has investigated the phenomenon in other species. Throughout the show, Caroline tries to understand why handedness exists in the first place and why our species is so biased to the right. She tries to answer listener Barb’s question as to why ambidexterity isn’t more ubiquitous, and it leads to some brainy tangents. We also hear questions from listeners Scotia and Roland, and travel to India with BBC reporter Chhavi Sachdev to hear how cultural norms are not in favour of lefties. Presenter: Caroline Steel Producer: Sam Baker Editor: Richard Collings Production co-ordinator: Jonathan Harris Studio engineers: Tim Heffer, Steve Greenwood Featuring: Marietta Papadatou-Pastou, Neuropsychologist and Assistant Professor, National and Kapodistrian University of Athens Sebastian Ocklenburg, Professor for Research Methods, Medical School Hamburg David Carey, Reader in Neuropsychology, Bangor University (Image: Close up of group of hands raised. Credit: JGI/Getty Images)

CrowdScience listener Ali wants to know why we experience vertigo. Anand Jagatia finds out that it’s not just the giddy sensation we feel when we’re at the top of a mountain. Vertigo is also a physical illness that can be triggered by a range of disorders. He talks to leading experts on balance to learn what causes the condition, discovers how virtual reality can help people with a phobia of being in high places and volunteers to be turned upside down to experience what it feels like to be treated for vertigo. Contributors: Peter Rea, consultant ENT surgeon, University Hospitals of Leicester, Honorary Professor of Balance Medicine, De Montfort University, Honorary Professor in Life Sciences, University of Leicester, UK Tammy Barker, clinical scientist, Balance Centre, Leicester Royal Infirmary, UK Rupal Rajani, broadcast journalist and member of Life on the Level Tara Donker, clinical psychologist, Freiburg University, Germany Andrew Hugill, composer, musicologist and deputy director, Institute for Digital Culture, University of Leicester, UK Presenter: Anand Jagatia Producer: Jo Glanville Editor: Richard Collings Production co-ordinator: Jonathan Harris Sound design: Julian Wharton Studio manager: Bob Nettles With thanks to Andrew Hugill for permission to include his composition Verdigrade, commissioned by The Space as part of ‘Culture in Quarantine’, BBC. Image: CrowdScience presenter Anand Jagatia tries out a machine for diagnosing and treating vertigo at Leicester Royal Infirmary Credit: Peter Rea

We all enjoy a deep-fried Mars bar with french fries from time to time, but why do we crave these unhealthy foods instead of healthy things like spinach or broccoli? And what is a food craving? The answers lie in a complex blend of our psychology, physiology, and even sociology. BBC CrowdScience presenter Alex Lathbridge savours a mystery-meat crocket with the experts on a quest to discover the hidden sources and sauces of our food cravings. Presenter: Alex Lathbridge Producer: Richard Walker Editor: Richard Collings Production co-ordinator: Jonathan Harris (Image: Stack of cheeseburgers and French fries. Credit: Dominic Lipinski/PA)

Please note: This is a shorter version than the original podcast. A longer version is available here - https://www.bbc.co.uk/sounds/play/w3ct3j6y. Humans can walk for miles, solve problems and form complex relationships using the energy provided by daily meals. That is a lot of output for a fairly modest input. Listener Charlotte from the UK wants to know: how efficient are humans? How do they compare to cars, other animals and even to each other? Presenter Marnie Chesterton pits her energetic self against everything from cars to rabbits to find out how she shapes up. Marnie also explores whether humans are born equal when it comes to fuel efficiency. Does the energy from one banana get converted into the same amount of movement from person to person? Marnie gets on a treadmill to find out how efficient she really is. With contributors from Herman Pontzer, Duke University, Rhona Pearce, Loughborough University and Christian Gammelgaard Olesen from Wolturnus wheelchair manufacturing company. Presenter: Marnie Chesterton Producer: Caroline Steel Editor: Richard Collings Production co-ordinator: Jonathan Harris (Image: Illustration of an airplane, a red car and a female wheel chair user. Credits: Getty Images)

CrowdScience listener Eileen cannot see images in her head of her memories. She only discovered by chance that most other people can do this. She wants to know why she can’t see them and if it is something she can learn to do. Anand Jagatia finds out what mental images are for and whether scientists know why some people can’t create them. Three per cent of the world’s population cannot see mental images like Eileen. And it is only recently been given a name – aphantasia. Anand discovers why mental images are useful, why they are sometimes traumatic and how people who are blind or visually impaired can also create images of the world around them. Contributors: Emily Holmes, professor of clinical psychology, Uppsala University, Sweden Adam Zeman, professor of cognitive and behavioural psychology, Exeter University, UK Joel Pearson, professor of cognitive neuroscience, University of New South Wales, Australia Paul Gabias, associate professor, Department of Psychology, University of British Columbia, Canada Marijke Peters, Hannah Fisher and Jo Glanville, CrowdScience producers Presenter: Anand Jagatia Producer: Jo Glanville Editor: Richard Collings Production co-ordinator: Jonathan Harris Sound: Jackie Margerum Image credit: Andriy Onufriyenko | GETTY IMAGES | Creative #1397973635

Welcome to the exciting new field of generative artificial intelligence - or generative AI. We’re not talking about robots or spaceships: instead these are image generators and chatbots that are already revolutionising the way people write, research and interact in the virtual world. Their capabilities are extraordinary. But before they can produce results they first need to be trained on vast amounts of data. And that’s what got CrowdScience listener Ian wondering. He says: “Before long, much of the material on the internet will have been written, or at least co-written, by AIs. What will happen when AIs are being trained on texts they have written themselves?” To answer this question Anand Jagatia first meets artist and scientist Michelle Huang. Michelle recently embarked on a therapy project to try and connect with her own “inner child”. She took a decade’s worth of her diaries from her childhood and fed them into an AI to try and simulate a conversation between her and her younger self. Can a machine convincingly recreate the voice of a human being? You can be the judge! Then, data scientist Briana Brownell joins Anand to explain a little about how ‘generative AI’ like this actually works. Together they open up the popular chatbot, ChatGPT, to put it to the test: but can it help Anand solve his personal conundrum? Now that we understand what AI is capable of we also need to know its limits. AI researcher Pablo Villalobos describes the process of training generative AI and where it gets its material from. The amount of data consumed in this way keeps going up and up, Pablo and his colleagues have been calculating exactly when that data is likely to run out. Pablo also discusses recent research exploring a unique effect that occurs if AI is repeatedly trained on its own material. Finally, Briana Brownell returns to cover a range of wider issues related to artificial intelligence and what effects it might have on our future. Presenter: Anand Jagatia Producer: Phil Sansom Editor: Richard Collings

CrowdScience listener Nyankami, from Kenya, has a friend with dementia. Despite memory loss and no longer knowing his way around, his friend has no problem communicating. So what’s the connection between memory and language? Caroline Steel discovers how dementia affects our speech. In most cases the illness does have an impact on our ability to speak but it can depend on many factors, including the type of dementia and even how many languages we speak. She meets George Rook, diagnosed with vascular dementia and Alzheimer’s, who’s a passionate campaigner for people with dementia and talks to dementia nurse Helen Green, who explains how the illness can affect our behaviour. She discovers that speaking more than one language can actually protect our brains from decline and finds out about cutting edge research that is helping people with dementia to improve their memory and capacity to speak. Featuring: George Rook, Lived Experience Advisory Panel, Dementia UK Helen Green, Admiral Nurse, specialising in dementia Professor Alex Leff, Professor of Cognitive Neurology, Institute of Neurology, University College London Professor Guillaume Thierry, Professor of Cognitive Neuroscience, Bangor University Professor Yan Jing Wu, Professor of Neurolinguistics, Ningbo University, China Dr Elizabeth Kuhn, Post-Doctoral Fellow, German Centre for Neurodegenerative Disease, Bonn Image Credit: Emma Innocenti Presenter: Caroline Steel Producer: Jo Glanville Editor: Richard Collings Production co-ordinator: Jonathan Harris Sound engineer: Jackie Margerum

It may seem like a simple question but could you explain why the earth revolves around the sun? That is what listener Josh from New York wants to know. For much of human history we thought everything revolved around us, literally. So how did humans come to the conclusion that we're not the centre of the universe? And how did the scientific process help us uncover the true order of things? Looking through telescopes from the vantage point of Australia, host Caroline Steel speaks with astronomers and physicists about the bumpy scientific journey to arrive at this discovery that we now take for granted. Delving into Indigenous astronomy with researcher Peter Swanton, Caroline questions whether Western scientists were really the first ones to grasp this understanding of our solar system. And at the Sydney Observatory, stellar astrophysicist Devika Kamath and Sydney Observatory host Nada Salama show Caroline some of the clues up in the sky that astronomers in the 1600s used to deduce that there was something wrong with earlier models of our solar system. Rhett Allain from Southeastern Louisiana University helps break down the physics concepts at play when it comes to the motion of our planets and the sun. Through her exploration of a seemingly simple question, Caroline asks some big questions as she looks up to the stars – about life, the universe, and the nature of science itself. Producer: Sam Baker Presenter: Caroline Steel Editor: Richard Collings Production co-ordinator: Jonathan Harris Featuring: Devika Kamath, Astrophysicist, Macquarie University Rhett Allain, Associate Professor, Southeastern Louisiana University Peter Swanton, Indigenous Research Associate, Australian National University (Photo: Caroline and Devika, Sydney Observatory)

Anyone who has ever enjoyed a beach holiday will know there’s something special about being by the seaside. But does sea swimming actually have tangible health effects? This week’s listener Holly is a self-confessed water baby, and says her regular surf sessions on Sydney’s iconic Bondi beach make her feel happier and look younger. But could we get some of the benefits from the beach without getting our feet wet? At the Plymouth Marine Lab, researchers have shown that the smell of the sea makes most people feel happier. They’re measuring sea spray aerosols containing natural compounds derived from algae, that dial down the inflammatory response in lung cancer cells. Other scientists in the region have investigated the use of virtual reality to simulate being by the coast, which is proven to reduce the experience of dental pain during treatment. Finally, we visit Teats Hill in Plymouth to find out how a waterside amphitheatre and an urban beach are helping residents feel safer and more connected to one another. Producer: Marijke Peters Presenter: Marnie Chesterton Editor: Richard Collings Production Coordinator: Jonathan Harris Contributors: Dr Frances Hopkins, Plymouth Marine Laboratory Dr Mike Moore, Plymouth Marine Laboratory Dr Mathew White, University of Vienna Dr Easkey Britton Image credit: David Sacks | The Image Bank | Getty Images | 164241179 Created for the #BBCWorldService.

Lazy. Unmotivated. Procrastinating. If those are words you’re used to hearing from your inner critic, you are not alone. Take CrowdScience listener Laurie. On her days off she loves to relax on the sofa, watch TV, put off chores and generally do as little as possible. Meanwhile she sees other family members and colleagues apparently buzzing with energy: going the extra mile at work, taking up hobbies, going to the gym. Why, she asks, is she so lazy? CrowdScience turns to experts to find out whether or not so-called ‘laziness’ is a fundamental part of biology or psychology; why some people have more energy than others; and we offer a few tips for boosting energy and motivation. Or maybe Laurie is just being a bit too hard on herself? With psychologists Professor Fuschia Sirois and Dr Devon Price, anthropologist Professor Herman Pontzer and start-up entrepreneur Akhil Aryan. Presented by Dr Alex Lathbridge Produced by Cathy Edwards for the BBC World Service Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Manager: Jackie Margerum Image: Asleep under a book (Credit: RichVintage via Getty Images)

Meet the ostrich, one of nature’s most unusual creatures: a two-metre-tall, flightless bird that struts about the African savannah. CrowdScience listener Pat found herself entranced by seeing them on a wildlife documentary, where two ostriches were exhibiting some bizarre behaviour. According to her, the female was sitting on her eggs in a ‘nest’ that was barely a dent in the ground, while the male was just flapping his feathers around her. So Pat came to us to ask: what are ostriches for? Anand Jagatia starts by meeting one face-to-face at Woburn Safari Park. Tom Robson, Head of Reserves at the park, gives Anand a tour of ostriches’ unique features. He discusses their status as the largest and fastest birds in the world and explains the unusual mating behaviour Pat observed on the TV programme she was watching. Next, to answer why some of these traits exist, Peter Houde from New Mexico State University dives into the ancient fossils. Peter is one of the palaeontologists who has managed to uncover the secrets of ostrich origins. What did their ancestors look like -- and why did they lose the ability to fly? Ostriches are also a part of human culture. Their eggs, for example, have been objects of value for thousands of years. Archaeologist Tamar Hodos from the University of Bristol explains how decorated ostrich eggs have been uncovered from ancient tombs and how they were probably used as pouring vessels as well as status symbols. Anand receives an ostrich egg in the post and manages to cook it using a very specific and British process. Finally, designer Pascale Theron tells us about the history of the ostrich farming industry. It’s a classic rags-to-riches-to-rags tale, a manic boom at the start of the 20th Century all based around feathers that were worth their weight in gold. Presenter: Anand Jagatia Producer: Phil Sansom Editor: Richard Collings Production Co-ordinator: Jonathan Harris Image credit: Phil Sansom & Anand Jagatia

Inside our gut lives an entire ecosystem of bacteria and microbes, called the microbiome. In fact, the human body contains trillions of microorganisms, which outnumber our cells by ten to one. This means that technically we are more microbe than human. But not only do these microbes rely on us to survive, we also rely on them for some vital bodily functions. So what impact do these trillions of microbes have on our health? That’s the question that’s been bothering CrowdScience listener Russell, from Canada. Presenter Caroline Steel investigates. She visits the only museum in the world dedicated to microbes to ask exactly what they are, what they do and why we have so many of them inside our bodies. And she visits a microbiology lab filled with model guts to find out what impact the microbiome has on our physical health and if there is anything we can do to help our microbes function better. Caroline finds out what impacts our microbiome, what we can do to improve our inner ecosystem, and how our microbes can take a disturbing turn on us after we die. Produced by Hannah Fisher and presented by Caroline Steel for the BBC World Service. Editor: Richard Collings Production Coordinator: Jonathan Harris Contributors: Professor Glenn Gibson – Professor of Microbiology, University of Reading Jasper Buikx – Microbiologist and Head of ARTIS Micropia David Good – Doctoral Candidate at the University of Guelph Image Credit: Microbiota of the human intestine/CHRISTOPH BURGSTEDT/SCIENCE PHOTO LIBRARY

CrowdScience listener Marie, in Sweden, has always had difficulty with her sense of time. She often thinks that events that happened years ago took place recently or that a holiday coming up is happening sooner than it is. So she wants to know if time is a sense, like the sense of taste or touch, and if it’s something she can learn. Anand Jagatia talks to scientists who’ve studied time, memory and how our brains process and store the events in our lives to find an answer to Marie’s question. Along the way he discovers why time speeds up as we get older, how our bodies register time passing and how our brains put everything that happens to us in order. Featuring: Dr Marc Wittmann, Institute for Frontier Areas in Psychology and Mental Health in Freiburg, Germany Dr Maï-Carmen Requena-Komuro, former PhD researcher, Dementia Research Centre, University College London Professor György Buzsáki, Neuroscience Institute, New York University Professor Adrian Bejan, Thomas Lord Department of Mechanical Engineering and Materials Science, Duke University Presenter: Anand Jagatia Producer: Jo Glanville Sound Design: Julian Wharton Production Co-ordinator: Jonathan Harris Image credit: Peter Cade/ Stone/ Getty Images

What are the actual chances of finding alien life? The idea of meeting an extra-terrestrial has ignited imaginations for hundreds of years, and it has also inspired real science: the Search for Extra-Terrestrial Intelligence - or Seti - is an organisation that brings together researchers across the world in pursuit of distant life forms. This same dream is on the mind of listener Andrew in Yorkshire in the UK, who has been looking into the sheer size of the universe, and wants to know: how many stars are there in existence, how many planets, and how many planets that could harbour life? Presenter Marnie Chesterton sets off on a space odyssey to answer these questions. She starts at Jodrell Bank Observatory in Cheshire, where University of Manchester astrophysicist Eamonn Kerins tells her the number of stars in the universe, and explains the Drake Equation - the mathematical formula that underpins SETI’s work. It is a series of seven numbers that combine to give you the probability of making contact with an alien civilisation. The next step after stars is the number of planets; Michelle Kunimoto of MIT, who works on Nasa’s TESS mission, explains the transit technique for finding distant worlds. Supposedly anyone can learn to use this technique, so Michelle puts Marnie to a test of her planet-hunting prowess. Distant planets are a huge leap forward - but not all of them will be hospitable to life. Eamonn breaks down how scientists define a habitable planet, as well as how to determine habitability using telescope observations. Marnie speaks to Mary Angelie Alagao from the National Astronomical Research Institute of Thailand about a cutting-edge piece of optical kit designed to block out the light from stars so you can take direct images of the planets next to them. Finally, it is time to put everything together and get some actual numbers for listener Andrew - as well ask how long it could take to find proof of alien life. Presenter: Marnie Chesterton Producer: Phil Sansom Production Coordinator: Jonathan Harris (Photo credit: Mark Garlick/Science Photo Library/Getty Images)

Compared to the entirety of human existence, our history of flying in aeroplanes is very short indeed. So what does this fast form of travel do to bodies that have evolved for land-based living? That's what listener Sofia wants to know after working as a flight attendant for over a decade. What effect does working at 35,000 feet have on one's health? How disruptive to your circadian rhythms is hopping across ten time zones in less than 24 hours? What's happening in our stomachs if a crisp packet blows up to the point of popping as the cabin pressure changes? And why do we feel so darn dehydrated when we get off a plane? Host Caroline Steel not only talks to the experts about everything from swollen ankles to what we should eat and drink on planes, she also records her own journey from London to Australia. She does just about everything wrong along the way, but the experts sort her out with some top tips for her next long-haul flight on how to avoid blood clots and even, how to avoid jet lag all together! While in Australia, Caroline also visits a sleep lab where researchers can simulate jet lag to learn how to improve flight safety and the wellbeing of flight attendants and pilots. Join Caroline on her journey as CrowdScience takes to the skies to find out what frequent flyers need to know when it comes cosmic ionising radiation and what we can all do to make that next flight a little more pleasant. Produced by Sam Baker for the BBC World Service. Featuring: Tony Schiemer, Senior Aviation Medical Officer, Royal Australian Air Force Eileen McNeely, Executive Director, SHINE at Harvard T. H. Chan School of Public Health Tracey Sletten, Senior Lecturer, Turner Inst for Brain & Mental Health, Monash University (Photo: Getty Creative # 1432221653)

How do we hear a sound and immediately know where it’s coming from? That’s the question that CrowdScience listener Chiletso asked himself one day as he heard his son bounce a ball and instantly knew its direction. In this ear-opening episode, presenter Anand Jagatia sets out to discover what makes left, right, up and down, sound so different. First, Anand gets blindfolded, so that Alan Archer-Boyd, former auditory scientist and lead engineer at BBC R&D, can put his sound localisation skills to the test. It turns out that having two ears and pinnae, those flappy bits of cartilage on the side of your head, help a lot. Professor Eric Knudsen shares how the barn owl’s asymmetrical ears allow it to hunt mice, even in complete darkness. And Anand uncovers how far he can push his own spatial hearing. Blind activist and researcher Thomas Tajo teaches him how to echolocate like a bat, and Dr Lore Thaler explains what is going on in the brain of experienced echolocators. If you can, listen on headphones! Presented by Anand Jagatia Produced by Florian Bohr for the BBC World Service Image: Boy with hands at his ears Credit: Silke Woweries/Getty Images

Sweating, nausea, chest pain and shortness of breath sound like the physical symptoms of a heart attack. For about 4% of the world’s population, they are also symptoms of an underdiagnosed condition that can leave sufferers curled in a ball and screaming on the floor. A CrowdScience listener wants to know why humans have panic attacks. Host Marnie Chesterton brings on board an expert co-presenter, novelist Tim Clare, to talk us through the hows and whys. Tim suffered from crippling panic attacks for over a decade. He decided enough was enough and has combed through the scientific literature, using himself as a guinea pig, to see what helped. Anxiety can be a useful sensation, helping you to detect and avoid dangers before they happen. But when that morphs into debilitatingly unpleasant symptoms, or an internal monologue saying “that’ll go badly, best to not leave the house”, something has gone wrong. Together, Tim and Marnie explore what’s going on in the brains of those whose threat circuit is faulty. Dr Olivia Remes, a mental health researcher at the University of Cambridge explains how common panic attacks are, and how they often present. Dr Bonnie Furzer at the University of Western Australia explains how exercise can help. Tim takes a dip to demonstrate how cold water, and the cold shock response can help. Dr Rebecca Taugher at the University of Iowa explains how scientists induce a panic attack in the lab, how she has been a guinea pig and why patient SM, without an amygdala, the brain’s so-called ‘fear-centre’, could still be given a panic attack in the lab, just by inhaling extra amounts of carbon dioxide. Professor Alexander Shackman from the University of Maryland points out that the science will come so much further when researchers look at a genuine cross-section of the population, rather than focussing on those in educational establishments (easier to study) who often don’t experience panic attacks. PHOTO CREDIT: Woman hyperventilating into paper bag Credit: Peter Dazeley/Getty Images

When imagining a robot, a hard-edged, boxy, humanoid figure may spring to mind. But that is about to change. CrowdScience presenter Alex Lathbridge is on a mission to meet the robots that bend the rules of conventionality. Inspired by how creatures like us have evolved to move, some roboticists are looking to nature to design the next generation of machines. And that means making them softer. But just how soft can a robot really be? Join Alex as he goes on a wild adventure to answer this question from listener Sarah. He begins his quest at the ‘Hello, Robot’ Exhibition at the Vitra Design Museum in Weil am Rhein, Germany to define what a robot actually is. Amelie Klein, the exhibition curator, states anything can be a robot as long as three specific criteria are met (including a cute cuddly baby seal). With this in mind, Alex meets Professor Andrew Conn from the Bristol Robotics Lab who demonstrates how soft materials like rubber are perfect contenders for machine design as they are tough to break and - importantly for our listener’s question - bendy. Alex is then thrown into a world of robots that completely change his idea of what machines are. He is shown how conventionally ‘hard’ machines are being modified with touches of softness to totally upgrade what they can do, including flexible ‘muscles’ for robot skeletons and silicon-joined human-like hands at the Soft Robotics Lab run by Professor Robert Katzschmann at ETH Zurich. He is then introduced to robots that are completely soft. Based on natural structures like elephant trunks and slithering snakes, these designs give robots completely new functions, such as the ability to delicately pick fruit and assist with search and rescue operations after earthquakes. Finally, Alex is presented with the idea that, in the future, a robot could be made of materials that are so soft, no trace of machine would remain after its use... Presenter: Alex Lathbridge Producer: Julia Ravey (Image: RoBoa in action on a rooftop in Zurich. Credit: Julia Ravey)

CrowdScience listener Eric, in New Zealand, has noticed his wisteria growing towards a neighbouring tree. He thinks that it actually knows where it’s going. But how can a plant have a sense of direction? Plants don’t have the advantage of brains or eyes, but that doesn’t seem to stop them from being clever enough to find out from their environment where to move and how to get there – all while being rooted to the spot. Marnie Chesterton visits the Natural History Museum and Kew Gardens in London, home to the largest collection of living plants in the world, to discover how plants make their manoeuvres, and talks to botanists and plant biologists for the latest findings on the mysterious life of climbing plants. Featuring: Dr Mariane Sousa-Baena, School of Integrative Plant Sciences, Cornell University Dr Ilia Leitch, Senior Research Leader, Kew Gardens Tom Freeth, Head of Plant Records, Kew Gardens Dr Silvia Guerra, Neuroscience of Movement Laboratory, Padua University Professor Christian Fankhauser, Centre for Integrative Genomics, Lausanne University Dr Sandra Knapp, Merit Researcher, Natural History Museum

If, like this week’s Crowdscience listener Lili, you’re an avid gymgoer, you may well have wondered where your fat disappears to when you exercise? Well, the short answer is that we convert it to energy that powers a whole range of physical processes, from breathing to walking as well as lying down and doing nothing. But the science behind energy expenditure is a little more complicated than that. Presenter Anand Jagatia pops on an exercise bike to have his metabolism measured, and learns that he may be relying on an entirely different source of fuel as he works up a sweat. But is all that hard work worth the effort it involves? Recent research suggests there's a limit to the number of calories us humans can burn, and that doing physical activity isn’t a sure-fire way to keep trim. Even hunter-gatherers who walk 13,000 steps a day have the same metabolic rate as the average American. So if working out isn't the best way to lose weight, how about harnessing our own fat to tackle the complications of obesity? It used to be thought brown fat was exclusive to babies (and bears) but we now know adults have some of it too, and it seems to play a vital role in combatting a range of chronic diseases including hypertension and diabetes. Presenter: Anand Jagatia Producer: Marijke Peters

Yoga benefits our health in many ways, say the yogis, but which claims are backed up by science? Can yoga actually alleviate depression, fix lower-back pain or even reduce cardiovascular disease? Presenter Marnie Chesterton gets into her Lotus (position) and finds out first-hand at a class. Whilst in warrior one, she discusses the potential physical and mental health benefits of this ancient art of stretching, balance and movement with her class teacher. Returning from mat to studio, Marnie puts some of those claims to experts around the globe. She investigates the evidence to find out whether health boosting properties are the key to yoga's enduring popularity. Pannalists: Rajvi Mehta Prof. Holger Cramer Dr Richard Davidson Presented by Marnie Chesterton Produced by Richard Walker

Why does the thought of giving a talk to an audience fill so many of us with sheer terror? Marnie Chesterton investigates for listener Nhial, who has seen his fellow students in Morocco become panic stricken at the prospect and wants to know the reason for our anxiety. According to one study, 77 per cent of us share that fear. Marnie finds out about the relationship between stress, our brains and our voices from research associate Dr Maria Dietrich at the University Hospital, Bonn University. She talks to Nhial’s tutor, Professor Taoufik Jaafari, at Hassan II University of Casablanca about the challenges facing his students. And she visits the National Theatre in London to get some expert training from Jeannette Nelson, head of voice, who works with some of the world’s leading actors. Could there be an evolutionary explanation for the purpose of public speaking? Is it something we actually need to be good at? Marnie asks evolutionary psychologist Professor Robin Dunbar at Oxford University and gets some surprising answers. She meets psychologist Dr Preethi Premkumar at London South Bank University, who has developed virtual reality therapy with colleagues at Nottingham Trent University, and tries out the treatment herself. Presenter: Marnie Chesterton Producer: Jo Glanville

We generate a huge amount of noise, whether it’s our rumbling roads, pumping parties, or talkative tourists. And the topic of noise also generates a lot of questions from our listeners. In this episode we explore three of them, with the help of acoustic scientist Kurt Fristrup and neuropsychologist Catherine Loveday. Listener Dominique finds it hard to experience even one minute of a natural soundscape without some intrusion of human-made noise. He wonders how noise pollution is affecting both the natural world and us humans. We discuss just how noisy our modern world is, and visit a National Park in California to hear how they’re encouraging more peace and quiet there. Meanwhile Michelle, having witnessed her husband wince in pain at the sound of squeaking takeaway boxes, asks why certain noises are particularly unpleasant or even painful to some people. And finally, Jennifer has a sonic mystery for us to solve: why does the time of day make such a difference to the distant noises reaching her remote home? With contributions from Professor Catherine Loveday, Dr Kurt Fristrup and Mia Monroe. Additional audio courtesy of the U.S. National Park Service/Patrick Myers, Dominique Laloux, Boise State University/Jesse Barber, and KCSU/Asher Korn Presenter: Anand Jagatia Producer: Cathy Edwards Studio Managers: Bob Nettles and Jackie Margerum

From Lawrence of Arabia to Star Wars via tales of intrepid adventurers traversing lonely sand-swept landscapes, deserts have always had a powerful pull on the popular imagination. But if a desert is full of sand, where did all that sand come from in the first place? That is what CrowdScience listener Andy wants to know, so presenter Caroline Steel heads off into the dunes to find out. She begins by finding out what a desert is anyway and whether it is always sandy, as well as tracing the flow of material across the huge, ever-shifting sand seas of the Sahara. From deserts fed by sand from mountains thousands of kilometres away, to dunes migrating across the entire continent of Africa, Caroline discovers how sand has just the right properties to be carried along by the wind. She also explores how the sand in every desert has a unique fingerprint, and finds out how fish bones in the Sahara tell the story of its lush, green past. Contributors: Dr Jo Nield, University of Southampton Dr Andreas Baas, Kings College London Dr Andrea Zerboni, University of Milan Presented by Caroline Steel Produced by Ben Motley for the BBC World Service (Photo: The Sahara desert near Timbuktu, Mali Credit: Jeff Overs)

When falling in love or fancying someone, one emotion can dominate over the rest: jealousy. Some may try to play it cool and act aloof, but seeing - or even thinking - of a romantic partner engaging with others can lead people to act completely out of character. The green-eyed monster can hijack thoughts for days to weeks on end, making us spend precious energy ruminating on situations that may never arise. So why is it that humans feel jealousy? Do people experience this emotion differently? And are there ways to stop it? CrowdScience presenter Caroline Steel sets about answering these questions from listener Odile in France, who has struggled with all-consuming jealousy in some romantic relationships. She hears about a kind of monkey that gets jealous of its own reflection from Professor Karen Bales at University California Davis. A trip to ZSL London Zoo sees more monkeys, but these are more bothered about protecting the vital friendships which aid their survival. Dr Alex Mielke from the University of St Andrews explains how these interactions can give us an insight into why jealousy exists. Some of us get more jealous than others and are more likely to act out of character when the green-eyed monster takes hold. Caroline completes a detailed questionnaire to see how jealous she really is, and gets advice from Julia in South Africa, who is in a polygamous marriage and has had to handle romantic jealousy. The nature-nurture balance of jealousy is untangled by geneticist Dr Laura Wesseldijk from Amsterdam UMC (who reveals some surprising information about the first author on her research paper…) and psychologist Dr Johan Ahlen from the Karolinska Institute rounds off the programme by discussing what the future of jealousy management could look like for those who struggle. Presenter: Caroline Steel Producer: Julia Ravey

When CrowdScience listener Eric spotted a few gnats flying around on a milder day in mid-winter it really surprised him - Eric had assumed they just died out with the colder weather. It got him wondering where the insects had come from, how they had survived the previous cold snap and what the implications of climate change might be for insect over-wintering behaviour? So he asked CrowdScience to do some bug investigation. CrowdScience presenter Marnie Chesterton takes up the challenge and heads out into the British countryside – currently teeming with buzzes and eight legged tiny beasties - to learn about the quite amazing array of tactics these small creatures use to survive the arduous days of cold. She hears how some insects change their chemical structure to enhance their frost resistance whist others hanker down in warmer microclimates or rely on their community and food stocks to keep them warm. But cold isn’t the only climatic change insects have to endure, in the tropics the seasons tend to fluctuate more around wet and dry so what happens then? Marnie talks with a Kenyan aquatic insect expert who describes how mosquitoes utilise the rains and shares his worry climate change could have a big impact on insect populations. Contributors: Dr Erica McAlister – Entomologist and Senior Curator, Natural History Museum, Dr Adam Hart – Entomologist and Professor of Science Communication - University of Gloucestershire Fran Haidon – Beekeeper Laban Njoroge – Entomologist, head of the Invertebrate Zoology – Museum of Kenya Dr Natalia Li – Biochemist Presenter: Marnie Chesterton Producer: Melanie Brown [Image: Butterfly in winter resting on snow covered branch. Credit: Getty Images]

ow do we stay up when we ride a bicycle? Lots of us can do it without even thinking about it, but probably very few of us can say exactly HOW we do it. Well, CrowdScience listener Arif and his children Maryam and Mohammed from India want to understand what’s going on in our heads when go for a cycle, and how we learn to do it in the first place. Presenter Marnie Chesterton is on the case, tracking down a neuroscientist studying how our brains and bodies work together to keep us balanced whether we’re walking or trying to ride a bicycle. She learns about the quirks of bicycle engineering from researchers in the Netherlands who are part of a lab entirely devoted to answering this question. In the process falling off of some unusual bicycles and uncovering the surprising truth that physics might not yet have a proper answer. And we peer deeper into our brains to find out why some memories last longer than others, whether some people can learn quicker than others and the best way to learn a new skill. Presented by Marnie Chesterton and Produced by Emily Bird for the BBC World Service. Featuring: Kathleen Cullen, Johns Hopkins University, USA Jason Moore, University of Technology Delft, The Netherlands Lara Boyd, University of British Columbia, Canada Rado Dukalski, University of Technology Delft, The Netherlands Josie and Freesia, Pedal Power [Image: Family riding bikes. Credit: Getty Images]

Over the past 12 months, CrowdScience has travelled the world, from arctic glacierscapes to equatorial deserts, to answer listeners’ science queries. Sometimes, the team come across tales that don’t quite fit with the quest in hand, but still draw a laugh, or a gasp. In this show, Marnie Chesterton revisits those stories, with members of the CrowdScience crew. Alex the Parrot was a smart bird, with an impressive vocabulary and the ability to count and do basic maths. He was also intimidating and mean to a younger parrot, Griffin, who didn’t have the same grasp of the English language. Scientist Irene Pepperberg shares the consequence of this work-place bullying.  Take a tour of the disaster room at ICPAC, the IGAD Climate Prediction and Applications Centre (ICPAC) based in Nairobi, Kenya. It’s a new building where scientists keep watch for weird new weather and passes that information to 11 East African countries. Viola Otieno is an Earth Observation (EO) Expert and she explained how they track everything from cyclones to clouds of desert locust. Malcolm MacCallum is curator of the Anatomical Museum at Edinburgh University in Scotland, which holds a collection of death masks and skull casts used by the Edinburgh Phrenological Society. Phrenology was a pseudoscience, popular in the 1820s, where individuals attempted to elucidate peoples’ proclivities and personalities by the shape of their heads. We see what the phrenologists had to say about Sir Isaac Newton and the “worst pirate” John Tardy. While recording on Greenland’s icesheet, the CrowdScience team were told by Professor Jason Box about “party ice.” 40,000 year old glacial ice is a superior garnish for your cocktail than normal freezer ice, apparently. This starts a quest for the perfect Arctic cocktail. Presented by Marnie Chesterton  Produced by Marnie Chesterton, featuring producers Florian Bohr, Sam Baker and Ben Motley  (Photo:)

Does your mum’s singing make you cringe with embarrassment? Do your dad’s jokes make you want to scream - and not with laughter? Or maybe you are the parent driving your offspring round the bend with rules and curfews? If so, you are not alone. CrowdScience listener Ilixo, age 11, has been wondering why it is that our parents become so annoying as we become teenagers. Is it something that is changing in his brain or are they actually becoming more annoying as they age? Presenter Marnie Chesterton consults our assembled panel of experts to discuss conflict between parents and their offspring. Developmental psychologist Liane Alampay, from the Ateneo de Manila University, Philippines, describes how the teenage experience varies around the world. Child and educational psychologist Laverne Antrobus in London says the teenage quest for independence is a normal - and necessary - developmental stage for becoming an adult. And Jennifer Lansford, a Research Professor at Duke University who studies parenting and child development, offers insights into the role peers play. Do not despair! - the panel offers tips for how to keep the peace - whether you’re an argumentative adolescent or a provoking parent. Producer: Lorna Stewart (Photo: Teenager putting fingers in ear while parent tries to talk to them. Credit: Getty Images)

CrowdScience listener David was playing snooker in Thailand when he started thinking how such a smooth ball was dependent on the rough green baize of the table to bring it to a stop. Would it be possible to play snooker at all in a completely frictionless universe? Sometimes friction produces heat. Could we ever control it completely? We try to reduce friction in some cases by using lubricants, whilst at other times like braking at a traffic junction we depend upon friction entirely. Anand Jagatia heads to Edinburgh in Scotland, UK, to meet some true masters of this mysterious entity: players of the winter sport Curling. What exactly is friction, and does thinking about it tell us something deeper about the universe? Taking part: Jennifer Dodds, Team GB Olympic Gold medallist Dave Lieth, Head of performance services, British Curling Susan Perkin, Professor of Physical Chemistry, University of Oxford Roger Lewis, Professor of Mechanical Engineering, University of Sheffield Presented by Anand Jagatia Produced by Alex Mansfield With thanks to David for his question. [Image: curling. Credit: Getty Images]

If your home is drafty, filling in holes and cracks can help tackle rising energy bills, and lower your carbon footprint. But is there a limit to how airtight we should make our homes? That’s what CrowdScience listeners Jeff and Angie wondered when weatherproofing their doors and sealing up cracks for the winter. Once every last gap is blocked, will enough air get in for them to breathe properly? How would they know if they’ve gone too far? With Covid-19 making us more aware than ever of the importance of good ventilation, CrowdScience investigates how to make your home cosy and energy-efficient without sacrificing fresh air in the process. And we find out how, in hotter climates, you can carefully tap into your drafts, to reduce energy-intensive air conditioning. With contributions from Kimble Smith, Professor Nicola Carslaw, Dr Iain Walker, Marion Baeli and Dr Yashkumar Shukla. Presented by Marnie Chesterton Produced by Cathy Edwards for the BBC World Service

What are the clouds like where you are? When you look upwards can you see great tufts of cotton wool, or do they stretch off into the distance, flat like sheets. Are they dark greys and purples, bringing the promise of rain or maybe there aren’t any at all. For listener John from Lincolnshire in the UK clouds looking up at the clouds is a favourite pastime and he wants to know why they look the way they do and why they are so different from one day to the next. Join Presenter Marnie Chesterton as we turn our gaze skyward to discover what gives clouds their shape. Join us for a cloud spotting mission with Gavin Pretor-Pinney, founder of the cloud appreciation society as he helps us de-code the shapes across the sky to reveal what they can tell us about our atmosphere. Dr Claire Vincent at the University of Melbourne introduces us to one of the superstars of the cloud world, Hector the Convector to explain where thunderstorms come from. And we learn how people like you can help NASA to understand the clouds better with Marilé Colón Robles project scientist at the GLOBE programme. Presented by Marnie Chesterton and Produced by Emily Bird [Image: Dramatic looking clouds. Credit: Getty Images]

As someone who dislikes crowds, listener Graham is curious about them. Crowds gather in all sorts of places, from train stations and football matches, to religious events and protest marches. But is there a science behind how they move and behave? To find out, Anand Jagatia speaks to some actual crowd scientists. He learns about the psychology of social identity, which influences everything from how close we stand to others to how we react in emergencies. He visits the Athens marathon, and hears about the algorithm that predicts how 50,000 runners will move through a city on race day. And he explores research into the science of riots, which explains why some peaceful crowds turn violent. Presented and produced by Anand Jagatia Contributors: Dr Anne Templeton, University of Edinburgh Marcel Altenburg, Manchester Metropolitan University Prof John Drury, University of Sussex Archive: BBC News Image: Crowd from above. Creidt: Getty Images

Why don’t we fall out of bed when we’re asleep? That’s the question that’s been keeping CrowdScience listener Isaac in Ghana awake, so presenter Alex Lathbridge snuggles up with some experts to find the answer. We get a lot of emails about sleep, so we’ve gathered together some of our favourite questions and put them to academics working on the science of snoozing. We’re wondering why some people laugh in their sleep, why some people remember their dreams and not others, and why we need to sleep at all - can’t we just rest? Our slumber scholars tell us about how our bodies continue to gather information while we’re asleep, how the tired brain is more likely to remember negative experiences, how we mimic other people in our sleep, and how sleep makes you more attractive to other people. And Alex takes a trip to the zzzzoo to meet some animals that have very different sleep patterns to humans. It’s his dream assignment. Contributors: Vanessa Hill, University of Central Queensland Professor Russell Foster, University of Oxford Mark Kenward, Drusillas Zoo Park Presented by Alex Lathbridge Produced by Ben Motley for the BBC World Service [Image: Man Falling into bed. Credit: Getty Images]

After learning how long it will take the Earth's ice sheets to melt in the previous episode, we continue our journey in Greenland. As world leaders gather in Egypt for the annual UN climate conference, listener Johan isn't too optimistic about governments' ability to curb greenhouse gas emissions and get a handle on climate change. So from his coastal perch in Denmark, he has asked where we should live when the poles have melted away and coastlines creep inland. Along with the help of BBC correspondents around the world, Marnie Chesterton scours the globe for the best option for listener Johan's new home. BBC Mundo reporter Rafael Rojas takes us to a manmade island off Colombia's Caribbean coast to see how we might be able to live with the seas. Meanwhile, reporter Furkan Khan takes us into the high, cold desert region of Ladakh to see if heading for the hills might be the answer. As Marnie searches for a climate-proof destination, she speaks to conservation biogeographer Matt Fitzpatrick, from the Appalachian Laboratory at the University of Maryland Center for Environmental Science. He's made a map that shows what towns and cities will feel like in 60 years and where you should visit in order to get a preview of your home's future climate. But Matt also tells us that we might not be the only ones on the move. And as climate scientist Ruth Mottram from the Danish Meteorological Institute tells us, waters are not going to rise evenly around the world. So can Marnie find a place to go, away from the expanding seas? Additional contributors: Alexander Atencio, environmental sustainability teacher, Santa Cruz del Islote, Colombia Sebastian Martinez, local leader, Santa Cruz del Islote, Colombia Professor Mohammad Din, Ladakh Environment and Health Organisation Ellen and Carl Fiederickson, teacher and sheep farmers, Qassiarsuk, Greenland Presenter: Marnie Chesterton Producer: Sam Baker

We know the Earth's atmosphere is warming and it's thanks to us and our taste for fossil fuels. But how quickly is this melting the ice sheets, ice caps, and glaciers that remain on our planet? That's what listener David wants to know. With the help of a team of climate scientists in Greenland, Marnie Chesterton goes to find the answer, in an icy landscape that's ground zero in the story of thawing. She discovers how Greenland’s ice sheet is sliding faster off land, and sees that the tiniest of creatures are darkening the ice surface and accelerating its melt. CrowdScience explores what we're in store for when it comes to melting ice. In the lead-up to yet another UN climate conference, we unpack what is contributing to sea level rise – from ice sheets in Greenland and Antarctica, to melting mountain glaciers and warming oceans. There's a lot of ice at the poles. The question is: how much of it will still be there in the future? Research Professor and climate scientist Jason Box from the Geological Survey of Denmark and Greenland shows us how much ice Greenland we've already committed ourselves to losing, even if we stopped burning all fossil fuels today. His team, including Jakob Jakobsen, show us how these scientists collect all this data that helps feed climate models and helps us all to understand how quickly the seas might rise. Professor Martyn Trantor from Aarhus University helps us understand why a darkening Greenland ice sheet would only add to the problem of melting. And climate scientist Ruth Mottram from the Danish Meteorological Institute breaks down how the ice is breaking down in Antarctica and other glaciers around the world. Presented by Marnie Chesterton and produced by Sam Baker for the BBC World Service Image: Greenland ice sheets. Credit: Getty Images

Record-breaking heatwaves swept across the Earth’s northern hemisphere this summer, while Australia experienced flooding and East Africa is enduring its worst drought in decades. Listener Geoff in Australia wants to know: Is climate change really responsible, or could it just be weather? Presenter Marnie Chesterton goes to Kenya, where the traditional Maasai way of life is at risk following a series of failed rainy seasons. She meets members of the Maasai community who have herded cattle for generations, who tell her how the unprecedented lack of rain is making it difficult to feed the animals, and themselves. She speaks to meteorologists and climate scientists to unpick the differences between weather and climate, discovering that not only is climate change affecting local weather systems, but it’s also affecting our ability to forecast it. She’ll also be learning about the IPCC report, and how there is no longer any doubt that climate change is a real and present threat to life on earth. Contributors: Esther Tinayo, Maasai villager Esther Kirayian, Maasai villager Patricia Nying’uro, Kenya Meteorological Department Abebe Tadege, IGAD Climate Prediction and Application Centre Professor Mark Maslin, University College London Presented by Marnie Chesterton Produced by Ben Motley, with Christine Yohannes, for the BBC World Service [Image credit: Getty Images]

Why do some people pick up accents without even trying, while others can live in another country for decades without ever losing the sound of their mother tongue? It’s a question that's been bothering CrowdScience listener Monica who, despite 45 years of living in the US, is still answering questions about where her accent is from. Presenter Marnie Chesterton sets off to discover why learning a new language is possible but perfecting the accent is so much harder. Marnie speaks to a linguist about how we learn language and develop our first accent, and what we can - and can't change - about our accents. A phonetician explains to Marnie the difficulty of even hearing sounds that are not from our mother tongue, let alone replicating them. And Marnie enlists some expert help to learn some of the pitch sounds of Japanese – with mixed success. Finally Marnie asks why people so dearly want to change their accents when doing so is such hard work. She hears from a sociolinguist about stereotypes and the impact of accent bias, and Shalu Yadav reports from the front line of Delhi call centres where workers experience prejudice about their accents regularly. Presented by Marnie Chesterton Produced by Lorna Stewart for the BBC World Service. Contributors: Yosiane White - Assistant Professor of Linguistics at University College Utrecht in the Netherlands Jane Setter - professor of phonetics at the University of Reading in the UK Akiko Furukawa - Reader in Japanese and Applied Linguistics at SOAS University of London in the UK Erez Levon - professor of sociolinguistics at the University of Bern in Switzerland. Shalu Yadav - BBC reporter in Delhi, India. [Image: woman with written words coming out of mouth. Credit: Getty images]

One in every eight people live with a mental health disorder, so if that’s not you, it’s likely to be a close friend or family member. Despite there being a variety of known treatments, globally the majority of people suffering do not receive any medical support. To see how the discussion around mental health is playing out across the African continent, CrowdScience visits Nairobi, Kenya. Presenter Marnie Chesterton is joined by a live audience and panel of experts - psychiatrist David Ndetei, psychotherapist Reson Sindiyo and mental health journalist Dannish Odongo - to get to the heart of what’s going on in our heads. They discuss issues from taboo and superstition around mental health, to the treatment methods being used in Kenya that the rest of the world should know about.

Human sexuality comes in many forms, from exclusively heterosexual to exclusively homosexual. But seeing as homosexuality creates apparent reproductive and evolutionary disadvantages, listener Ahmed from Oslo wants to know: why are some people gay? CrowdScience presenter Caroline Steel examines what science can - and can't - tell us about the role of nature, nurture and evolution in human sexual attraction. She asks a geneticist what we know of the oft-debated 'gay gene', as well as looking into why homosexual men on average have more older brothers than heterosexual men. Caroline looks into the role of nurture with a developmental psychologist to answer a question from a CrowdScience listener from Myanmar. He wonders if the distant relationship he has with his own father has impacted his own feelings of attraction. She also learns about research into a group of people in Samoa who may shed light on the benefits of traditionally non-reproductive relationships for communities as a whole. Presented by Caroline Steel Produced by Jonathan Blackwell for BBC World Service Contributors: Dr. Kevin Mitchell – Associate Professor of Genetics and Neuroscience, Trinity College Dublin Dr. Malvina Skorska - Postdoctoral Fellow at the Centre for Addiction and Mental Health, Toronto Prof. Lisa Diamond - Professor of Psychology and Gender Studies, University of Utah Prof. Paul Vasey, Professor and Research Chair, Department of Psychology, University of Lethbridge Vaitulia Alatina Ioelu, Chief Executive Officer, Samoa Business Hub (Photo credit: Ahmed Umar)

There are over 30,000 species of fish – that’s more than all the species of amphibians, reptiles, birds and mammals combined. But despite the sheer diversity of life on Earth, we still tend to think of all fish in roughly the same way: with an oblong scaley body, a tail and pairs of fins. Why? And is that really the case? Crowdscience listener and pet fish-owner Lauria asked us to dive into the depths of this aquatic world to investigate why fish are shaped the way they are. Do we just think that fish are all the same because we are land-dwelling? Presenter Anand Jagatia makes a splash exploring the fascinating story of fish evolution, how they came to be such a different shape from mammals and even how some mammals have evolved to be more like fish. Produced by Hannah Fisher and presented by Anand Jagatia for the BBC World Service. Contributors: Professor Frank Fish – Professor of Biology, West Chester University Dr Carla McCabe - Lecturer in Sport & Exercise Biomechanics Dr Andrew Knapp – postdoctoral researcher at the Natural History Museum, London Image: School of fish in shape of fish. Credit: Getty Images

CrowdScience listener Alix has a burning question - what’s actually happening inside the flames of a campfire to make it glow? And why do some materials burn easily, while others refuse to light at all? To find out, Alex Lathbridge travels to the Fire Research Centre at the University of Edinburgh to (safely) set various things ablaze. He learns about the fundamentals of fire and why things react differently to heat. He then heads to archives of the Royal Institution of London, to see an invention from the 19th century that can stop a fireball in its tracks: the miner’s safety lamp, which saved countless lives. And he speaks to a chemist about the science of flame retardants, and how even though they can make products less flammable, they may also have unintended consequences. Presenter: Alex Lathbridge Producer: Anand Jagatia Contributors: Dr Rory Hadden, University of Edinburgh Charlotte New, Royal Institution Dan Plane, Royal Institution Professor Richard Hull, University of Central Lancashire

Laugh and the world laughs with you, or so you might think. But watch any good comedian on TV by yourself and chances are you’ll laugh a lot less than if you were sat in a lively comedy crowd watching the same comedian in the flesh. But why is that? Do people from different cultures and corners of the world all laugh at the same things? These are questions raised by CrowdScience listener Samuel in Ghana who wonders why he’s always cracking up more easily than those around him. Presenter Caroline Steel digs into whether it’s our personality, the people around us, or the atmosphere of the room that determines how much we giggle, following neuroscience and psychology on a global trail in search of a good laugh. Producer: Richard Walker Presenter: Caroline Steel [Image: Two Women laughing. Credit: Getty Images]

Mathematics and our ability to describe the world in terms of number, shape and measurement may feel like a uniquely human ability. But is it really? Listener Mamadu from Sierra Leone wants to know: can animals count too? CrowdScience presenter Marnie Chesterton goes on a hunt to uncover the numerical abilities of the animal kingdom. Can wild lions compare different numbers? Can you teach bees to recognise and choose specific amounts? And if the answer is yes, how do they do it? Marnie tries to find out just how deep the numerical rabbit hole goes… and comes across a parrot named Alex who is perhaps the most impressive example of animal counting of them all. Contributors: Brian Butterworth - emeritus professor of cognitive neuropsychology at University College London Mai Morimoto - researcher at Queen Mary University of London Lars Chittka - professor of sensory and behavioural ecology at Queen Mary University of London Irene Pepperberg - comparative psychologist, and research associate at Harvard University Sounds: Lions from Karen McComb, emeritus professor at University of Sussex Túngara frogs from Michael Ryan, professor of zoology at University of Texa at Austin Presenter: Marnie Chesterton Producer: Florian Bohr

When CrowdScience listener Eric spotted a few gnats flying around on a milder day in mid-winter it really surprised him - Eric had assumed they just died out with the colder weather. It got him wondering where the insects had come from, how they had survived the previous cold snap and what the implications of climate change might be for insect over-wintering behaviour? So he asked CrowdScience to do some bug investigation. CrowdScience presenter Marnie Chesterton takes up the challenge and heads out into the British countryside – currently teeming with buzzes and eight legged tiny beasties - to learn about the quite amazing array of tactics these small creatures use to survive the arduous days of cold. She hears how some insects change their chemical structure to enhance their frost resistance whist others hanker down in warmer microclimates or rely on their community and food stocks to keep them warm. But cold isn’t the only climatic change insects have to endure, in the tropics the seasons tend to fluctuate more around wet and dry so what happens then? Marnie talks with a Kenyan aquatic insect expert who describes how mosquitoes utilise the rains and shares his worry climate change could have a big impact on insect populations. Contributors: Dr Erica McAlister – Entomologist and Senior Curator, Natural History Museum, Dr Adam Hart – Entomologist and Professor of Science Communication - University of Gloucestershire Fran Haidon – Beekeeper Laban Njoroge – Entomologist, head of the Invertebrate Zoology – Museum of Kenya Dr Natalia Li – Biochemist Presenter: Marnie Chesterton Producer: Melanie Brown [Image: Butterfly in winter resting on snow covered branch. Credit: Getty Images]

Have you ever wondered why waterfalls appear white when still water is transparent? Why clouds, or snow, appear white when they too are essentially just water molecules in different states? What makes something white, opaque or transparent? These are the questions CrowdScience listener Gerardo has been pondering ever since taking in the beauty of fallen water on a hiking trail in his home of Cantabria, Northern Spain. Presenter Marnie Chesterton, sets off on a quest to find out the answers to all of those questions and more. What even is white? Is it a colour, the absence of colour or all the colours of the rainbow combined? Is black really the opposite of white? And what colours do we mix to make white or black paint? Image: White paint in pots and a paintbrush. Credit: Getty Images

Imagine waking up to the smell of freshly baked bread. Doesn’t it make your mouth water? Now imagine the smell of a fish market on a warm day… still feeling hungry? CrowdScience listener Thanh from Vietnam is intrigued by the effects of smell on our appetite, and wants to know whether certain aromas can make us feel more full than others. Never averse to a food-based challenge, presenter Anand Jagatia takes us on a journey from the nose to the brain, where we find out what exactly happens when we get a whiff of various foods. He discovers how the digestive system prepares for a meal and the extent to which our stomach has a say in whether or not we want to eat, based on how appetizing the smells are around us. Anand also explores our cultural differences. In some parts of the world a stinky Limburger cheese is considered a delicacy, while in other places it could make people lose their lunch. We’ll find out why some of us get triggered in different ways than others.

From dumping raw sewage into rivers to littering the streets with our trash, humans don’t have a great track record when it comes to dealing with our waste. It’s something that CrowdScience listener and civil engineer Marc has noticed: he wonders if humans are particularly prone to messing up our surroundings, while other species are instinctively more hygienic and well-organised. Are we, by nature, really less clean and tidy than other animals? Farming and technology have allowed us to live more densely and generate more rubbish - maybe our cleaning instincts just aren’t up to the vast quantities of waste we spew out? CrowdScience digs into the past to see if early human rubbish heaps can turn up any answers. We follow a sewer down to the River Thames to hear about The Great Stink of Victorian London; turn to ants for housekeeping inspiration; and find out how to raise hygiene standards by tapping into our feelings of disgust and our desire to follow rules. Presented by Marnie Chesterton and produced by Cathy Edwards for the BBC World Service. [Image: Man on beach with rubbish. Credit: Getty Images]

You have probably experienced an ‘earworm’ - a catchy bit of music that plays round and round in your head and won’t go away – at least for a short while. But why did it pop up in the first place and how did it get stuck? CrowdScience listener Ryota in Japan wants us to dig into earworms, so presenter Datshiane Navanayagam bravely puts on her headphones to immerse herself in the world of sounds that stick. She meets with a composer of children’s songs as well as music psychologists to find out if there is a special formula to creating catchy songs and probes if this musical brain quirk serves any useful purpose. Datshiane then explores whether some people are more prone to catching earworms than others. Finally, for those who find this phenomenon disturbing - she asks is there a good way of getting rid of them? Come join us down the audio wormhole - disclaimer - the BBC is not responsible for any annoying earworms caused by this broadcast. Presented by Datshiane Navanayagam and produced by Melanie Brown Interviewees: Kelly Jakubowski – Assistant Professor in Music Psychology, Durham University Bill Sherman – Musical Director of Sesame Street Ashley Burgoyne – Computational Musicologist, University of Amsterdam [Image: Audio Cassette. Credit: Getty Images

We are running out of ammunition against certain infections, as bacteria increasingly evade the antibiotics we’ve relied on for nearly a century. Could bacteriophages – viruses that hunt and kill bacteria – be part of the solution? In 2019, CrowdScience travelled to Georgia where bacteriophages, also known as phages, have been used for nearly a hundred years to treat illnesses ranging from a sore throat to cholera. Here we met the scientists who have kept rare phages safe for decades, and are constantly on the look-out for new ones. Phages are fussy eaters: a specific phage will happily chew on one bacteria but ignore another, so hunting down the right one for each infection is vital. Since then, we’ve lived through a pandemic, the medical landscape has been transformed, and interest in bacteriophages as a treatment option is growing throughout the world. We turn to microbiologist Professor Martha Clokie for updates, including the answer to listener Garry’s question: could phages help in the fight against Covid-19? Contributors: Prof Martha Clokie, University of Leicester Dr Naomi Hoyle, Eliava Phage Therapy Center Prof Nina Chanishvili, Eliava Institute Dr Eka Jaiani, Eliava Institute Presented by Marnie Chesterton Produced by Cathy Edwards and Louisa Field for the BBC World Service [Photo:Bacteriophages infecting bacteria, illustration. Credit: Getty Images]

Artists can conjure up people, cities, landscapes and entire worlds using just a pencil or a paintbrush. But some of us struggle to draw simple stick figures or a circle that’s round. CrowdScience listener Myck is a fine artist from Malawi, and he’s been wondering if there’s something special about his brain. Myck takes Marnie Chesterton on a tour of his studio, where he paints onto huge canvases sewn from offcuts of local fabric. He’s a self-taught artist and he’s convinced he sees things differently to other people. So where does that all come from? Do artists have different brains from non-artists? And what is it that makes someone a creative person, while others are not? With the help of a jigsaw puzzle, a large metal donut, a swimming cap covered in electrodes and and a really boring brick, Marnie probes the brains of people working to find answers to those questions. She’ll be learning about how we don’t really see what we think we see, why creative people’s brains are like private aeroplanes, and how daydreaming can be a full time job. Contributors: Rebecca Chamberlain, Goldsmiths University of London Robert Pepperell, Cardiff School of Art Ariana Anderson, UCLA Darya Zabelina, University of Arkansas Presented by Marnie Chesterton Produced by Ben Motley for the BBC World Service

Hair is an important part of our identities – straight, frizzy, long, not there at all – and our efforts to keep it styled and clean have created an $80 billion hair care industry. Many products offer to improve the life of the stuff on our heads, but isn't it all just dead protein? CrowdScience listener Toria wants to know what 'healthy' hair really means. To untangle the science behind hair, we zoom in to see how hair grows from the follicles in our scalp and explore how the hair growth process will change over our lifetimes. Changes in our hair and disorders affecting the scalp can often have emotional impacts on our lives, as presenter Marnie Chesterton learns from a dermatologist who specialises in hair issues. Having been on a journey with her own hair in recent years following chemotherapy, Marnie is ready for a new 'do and ventures to the hair salon to find out about the health of her own hair. Meanwhile, another CrowdScience listener, Lucy, wonders why humans lost hair (or fur) on most of our bodies when most other mammals are covered in the stuff. A biological anthropologist who studies not only why hair became concentrated on our heads, but also why there's so much diversity in hair types across humans, unpacks the evolutionary benefits. With all these different hair types, does different hair need different care? And when it comes to shampoo, conditioner, washing, blowdrying and dyeing, what should we be doing to keep our hair structure sound? As we learn about this strange nonliving feature of our bodies, Marnie finds a new appreciation for the "dead strands of protein sticking out of our skin". And with listener Toria's help and advice, she also finds a new shade for her chemo-curled locks. Presented by Marnie Chesterton and produced by Sam Baker for BBC World Service. Featuring: ● Tina Lasisi, Penn State Department of Anthropology ● Sharon Wong, Consultant Dermatologist ● Ekwy Chukwuji-Nnene, Equi Botanics

Death is inevitable, though many of us would rather not dwell on it. For those with a terminal illness, however, the end of life is clearly a more pressing reality. CrowdScience listener Sam has known for a while that her illness is terminal, and by now she’s got used to the idea. But she finds many friends and family would rather avoid the subject at all costs; they don’t want to acknowledge what’s happening until it’s all over. She’s wondering if there’s a way to lighten up the topic of her approaching death, and create the openness she craves. If we could learn to be more accepting of illness and dying, the end of life could be a more positive experience for all involved. So how can we face up to the impending death of a loved one, and best support that person in the process? In search of answers, we talk a clinical psychologist about death anxiety, visit a death café, and learn about a scheme in India where whole communities are trained in caring for people at the end of life. With Dr Rachel Menzies, Abigail Griffin, Dr Suresh Kumar and Rebecca Nellis. Thanks to Lola, Juan, Leon, Qayyah, Bessy, Madhumita, Ashley, Amaru, Mila and Sheila. Presented by Caroline Steel Produced by Cathy Edwards for the BBC World Service [Image: A woman sitting next to her sister who has cancer. She is wearing a headscarf. Credit: Getty Images]

Every year, new computers are being developed that are faster and smarter than ever before. But if you really want to take things to the next level, you've got to go quantum. CrowdScience listener Atikah in Hungary likes the sound of a quantum computer but wants to know: what exactly is it, what can it do that a normal computer can't, and how soon can she get hold of one? The digital devices in our everyday lives - from laptop computers to smartphones - are all based on 0s and 1s: so-called ‘bits’. But quantum computers are based on ‘qubits’ - the quantum 0s and 1s that are altogether stranger, but also more powerful. With the help of quantum computing researcher Jessica Pointing and a spinning doughnut, presenter Alex Lathbridge learns how these ‘qubits’ allow computers to perform calculations millions of times faster than normal. While quantum computers do exist, it turns out they're not yet big enough or stable enough to be really useful. Alex visits Professor Winfried Hensinger and his prototype quantum computer at the University of Sussex to understand what they can do right now, and why it’s so incredibly difficult to scale them up. He hears from the engineers racing to overcome the obstacles and unlock the potential of these mega-powerful systems. But once the engineering problems are solved, what then? Professor Shohini Ghose opens our eyes to the exciting range of possible applications - from helping create new drugs, to making electric batteries much more efficient and maybe even helping farmers fertilise their crops for a fraction of the price. Contributors - Jessica Pointing, Professor Winfried Hensinger, Professor Shohini Ghose Presenter - Alex Lathbridge Producer - Ilan Goodman Sound Design - Jon Nicholls [Image: Winfried Hensinger in his lab at the University of Sussex, Credit: Universal Quantum]

Humans can walk for miles, solve problems and form complex relationships using the energy provided by daily meals. That is a lot of output for a fairly modest input. Listener Charlotte from the UK wants to know: how efficient are humans? How do they compare to cars, other animals and even to each other? Presenter Marnie Chesterton pits her energetic self against everything from cars to rabbits to find out how she shapes up. Marnie also explores whether humans are born equal when it comes to fuel efficiency. Does the energy from one banana get converted into the same amount of movement from person to person? Marnie gets on a treadmill to find out how efficient she really is. With contributors from Herman Pontzer, Duke University, Rhona Pearce, Loughborough University and Christian Gammelgaard Olesen from Wolturnus wheelchair manufacturing company. Presenter: Marnie Chesterton Producer: Caroline Steel Editor: Richard Collings Production co-ordinator: Jonathan Harris Art Design: Jonathan Harris Image credits: Airplane: Credit: Ghrzuzudu Creative #:1337512445 Red car: Credit: EgudinKa Creative #:625457854 Wheelchair Woman: Credit: Ponomariova_Maria Creative #:1401730072 Getty Images

This week’s CrowdScience is dedicated to bodily fluids – and why humans spend so much time spraying them all over the place. From snot and vomit to sweat and sneezes, listeners have been positively drenching our inbox with queries. Now presenter Marnie Chesterton and a panel of unsqueamish expert guests prepare themselves to wade through… One listener has found that as he ages, bright light seems to make him sneeze more and more – with his current record sitting at 14 sneezes in a row. He’d like to know if light has the same effect on other people and why? Sticking with nasal fluids, another listener wants to know why she’s always reaching for a tissue to blow her endlessly dripping nose and yet her family seem to produce hardly any snot at all. Could it be because she moved from a hotter climate to a colder one? CrowdScience reveals the answers to these and other sticky questions… if you can find the stomach to listen. Produced by Melanie Brown Contributors: Jagdish Chaturvedi – ENT Surgeon Åsmund Eikenes – Author Prof. Lydia Bourouiba - Associate Professor of Civil and Environmental Engineering, MIT Rubiaya Hussain – PhD student, optics and photonics, ICFO [Image: Woman sneezing. Credit: Getty Images]

If you go outside with a spade and start digging, the chances are you won't find any gold. You might get lucky or just happen to live in a place where people have been finding gold for centuries. But for the most part, there'll be none. But why is that? Why do metals and minerals show up in some places and not others? It's a question that's been bothering CrowdScience listener Martijn in the Netherlands, who has noticed the physical effects of mining in various different places while on his travels. It’s also a really important question for the future – specific elements are crucial to modern technology and renewable energy, and we need to find them somewhere. Marnie Chesterton heads off on a hunt for answers, starting in a Scottish river where gold can sometimes be found. But why is it there, and how did it get there? Marnie goes on a journey through the inner workings of Earth's geology and the upheaval that happens beneath our feet to produce a deposit that’s worth mining. On the way she discovers shimmering pools of lithium amongst the arid beauty of the Atacama Desert, meets researchers who are blasting rocks with lasers and melting them with a flame that’s hotter than the surface of the sun, and heads to the bottom of the ocean to encounter strange potato-sized lumps containing every single element on Earth. And maybe, just maybe, she’ll also find gold. Contributors: Leon Kirk, gold panning expert Holly Elliott, University of Derby Jamie Wilkinson, Natural History Museum, London Corrado Tore, SQM, Chile Yannick Buret, Natural History Museum, London Andrea Koschinsky, Jacobs University, Bremen Presented by Marnie Chesterton Report by Jane Chambers Produced by Ben Motley for the BBC World Service [Image: Hands holding Gold Nuggets. Credit: Getty Images]

Digging and excavating are bywords for archaeology. But why does history end up deep under our feet? This question struck CrowdScience listener Sunil in an underground car park. Archaeological remains found during the car park’s construction were displayed in the subterranean stairwells, getting progressively older the deeper he went. How had these treasures become covered in so much soil over the centuries? CrowdScience visits Lisbon, the capital of Portugal – and home to the above-mentioned multi-storey car park. The city has evidence of human habitation stretching back into prehistory, with remnants of successive civilisations embedded and jumbled up below today’s street level. Why did it all end up like this? Human behaviour is one factor, but natural processes are at work too. Over at Butser Ancient Farm, an experimental archaeology site in the UK, we explore the myriad forces of nature that cover up – or expose - ancient buildings and artefacts over time. Contributors: Dr Mariana Nabais, University of Lisbon Carolina Grilo, Lisbon Museum of the Roman Theatre Dr Matt Pope, University College London Presented by Marnie Chesterton, Produced by Cathy Edwards for the BBC World Service. IMAGE: Getty Images

Most people are great at remembering key points from important events in their lives, while the finer details - such as the colour of the table cloth in your favourite restaurant or the song playing on the radio while you brushed your teeth - are forgotten. But some people seem to have the power to remember events, documents or landscapes with almost perfect recall, which is widely referred to as having a photographic memory. Crowdscience listeners Tracy and Michael want to know if photographic memory actually exists and if not, what are the memory processes that allow people to remember certain details so much better than others? Putting her own memory skills to the test along the way, presenter Marnie Chesterton sets out to investigate just what’s happening inside our brains when we use our memories, the importance of being able to forget and why some people have better memories than others. Produced by Hannah Fisher and presented by Marnie Chesterton for the BBC World Service. Contributors: Stephen Wiltshire Annette Wiltshire Dr Farahnaz Wick Professor Craig Stark [Image credit: Getty Images]

Humans now have the ability to directly change their DNA, and gene-editing tool CRISPR has led to a new era in gene-editing. CrowdScience listener ‘Bones’ wants to know how gene-editing is currently being used and what might be possible in the future. Gene-editing offers huge opportunities for the prevention and treatment of human diseases, and trials are currently underway in a wide range of diseases like sickle cell anaemia. CrowdScience presenter Caroline Steel finds out about some of the most promising work tackling disease before turning to consider the possibilities of using gene editing to enhance ourselves. Will we be able to extend human longevity, swap our eye colour or improve athletic performance? And even if we can do all these things, should we? As scientists push the boundaries of gene-editing and some people are DIY experimenting on themselves with CRISPR, we discuss the practical and ethical challenges facing this promising but potentially perilous area of science. Produced by Melanie Brown and presented by Caroline Steel for the BBC World Service Contributors: Prof George Church Prof Waseem Qasim Jimi Olaghere Josiah Zayner Prof Joyce harper Prof Julian Suvalescu

How do we stay up when we ride a bicycle? Lots of us can do it without even thinking about it, but probably very few of us can say exactly HOW we do it. Well, CrowdScience listener Arif and his children Maryam and Mohammed from India want to understand what’s going on in our heads when go for a cycle, and how we learn to do it in the first place. Presenter Marnie Chesterton is on the case, tracking down a neuroscientist studying how our brains and bodies work together to keep us balanced whether we’re walking or trying to ride a bicycle. She learns about the quirks of bicycle engineering from researchers in the Netherlands who are part of a lab entirely devoted to answering this question. In the process falling off of some unusual bicycles and uncovering the surprising truth that physics might not yet have a proper answer. And we peer deeper into our brains to find out why some memories last longer than others, whether some people can learn quicker than others and the best way to learn a new skill. Presented by Marnie Chesterton and Produced by Emily Bird for the BBC World Service. Featuring: Kathleen Cullen, Johns Hopkins University, USA Jason Moore, University of Technology Delft, The Netherlands Lara Boyd, University of British Columbia, Canada Rado Dukalski, University of Technology Delft, The Netherlands Josie and Freesia, Pedal Power

The ancient Maya flourished in modern day Mexico and Central America for millennia. They built incredible cities and they had sophisticated knowledge of astronomy, architecture and the natural world. But although Maya culture continues to exist today, around 900 AD, many of their great settlements collapsed, and today they lie in ruins. CrowdScience listener Michael wants to know - how did the Maya sustain their populations successfully for so long? And what happened 1000 years ago that led them to abandon their cities? To find out, presenter Melanie Brown travels to the forests of Western Belize. She visits the archaeological site of Xunantunich to learn about what life would have been like for the Maya living in what was once a prosperous city. She hears about the importance of water to the Maya way of life in this region, and their ingenious methods for capturing and storing rainfall. She meets archaeologists using lasers and drones to map Maya settlements that have lain hidden by jungle for centuries. And she discovers what material from the bottom of lakes can tell us about how the Maya faced a changing climate, which may have had huge consequences for their society. This episode is being released on Earth Day 2022. As we face an uncertain future of our own amid a climate crisis, are there any lessons we can learn from the Maya about how to live sustainably on this planet? Presented by Melanie Brown and produced by Anand Jagatia Featuring: Elias Cambranes, Maya expert and tour guide Prof Lisa Lucero, University of Illinois Urbana-Champaign Prof Tim Murtha, University of Florida Dr Eben Broadbent, University of Florida Prof Mark Brenner, University of Florida Photo: Ancient ruins of the Mayas deep in the forest of Belize Credit: Simon Dannhauer/Getty Images

The team at CrowdScience have spent years answering all sorts of listener questions, which must make them pretty smart, right? IN this week’s episode, that assumption is rigorously tested as Marnie Chesterton and the team pit their wits against a multitude of mindbending puzzles from an old TV gameshow - all in the name of answering a question from Antonia in Cyprus. She wants to know: how do we work out how clever someone is? Is IQ the best measure of cleverness? Why do we put such weight on academic performance? And where does emotional intelligence fit into it all? In the search for answers, presenter Marnie Chesterton and the team are locked in rooms to battle mental, physical, mystery and skill-based challenges, all against the clock. Unpicking their efforts in the studio are a global team of cleverness researchers: Dr Stuart Ritchie from Kings College London, Professor Sophie von Stumm from York University and Dr Alex Burgoyne, from Georgia Institute of Technology in the US. They are challenged to face the toughest questions in their field: Why do men and women tend to perform differently in these tests? Is our smartness in our genes? And what about the Flynn effect – where IQs appear to have risen, decade after decade, around the world. Produced by Marnie Chesterton on BBC World Service [Image: Man doing puzzle. Credit: Getty Images]

The odds of becoming a fossil are vanishingly small. And yet there seem to be an awful lot of them out there. In some parts of the world you can barely look at a rock without finding a fossil, and museum archives worldwide are stuffed with everything from ammonites to Archaeopteryx. But how many does that leave to be discovered by future fossil hunters? What’s the total number of fossils left to find? That’s what listener Anders Hegvik from Norway wants to know and what CrowdScience is off to investigate. Despite not having the technology or time to scan the entire planet, presenter Marnie Chesterton prepares to find a decent answer. During her quest, she meets the scientists who dig up fossils all over the world; does some very large sums; and asks, have we already found all the T-rexes out there? Presented by Marnie Chesterton and produced by Anna Lacey (Photo: Fossilized dinosaur bones and skull in the send. Credit: Getty Images)

Many animals undertake remarkable migratory journeys; travelling thousands of miles only to return to same burrow or beach they departed from. Yet, unlike humans, they don’t have digital or paper maps to guide their way, so how are they able to orientate themselves with such accuracy? In the second part of this migration story, CrowdScience’s Anand Jagatia explores how animals are able to navigate using the sun, stars, smells, landmarks and magnetism to help guide them. Anand journeys to the coast of Florida where he helps to place a satellite tracker on a sea turtle in order to follow the long-distance journeys of these animals. He then visits a lab in North Carolina to meet a team that is recreating the earth’s magnetic fields to examine how sea turtles might be using these forces to find their feeding and nesting grounds. Anand wades into the hotly contested topic of just how birds may be sensing magnetic fields – and hears about one of the latest theories that suggests birds eyes may be exploiting quantum physics. The range of navigational tools we encounter throughout the animal kingdom from whales to ants is beguiling, Anand asks what does our increased understanding of these feats might mean for animal conservation as well as human development of mapping systems. Contributors: David Godfrey – Sea Turtle Conservancy Rick Herren – University of Florida Tim Guilford – University of Oxford Ken Lohmann – University of North Carolina Kayla Goforth – University of North Carolina Henrik Mouritsen – University of Oldenburg (Photo: Sea Turtles. Credit: Getty Images)

Wherever you are in the world you are probably near an animal that has undertaken a remarkable migratory journey, be that a butterfly, bird or sea turtle. But what CrowdScience listener Moses in Kenya wants to know is why they bother making such long and precarious voyages - and how they're able to reliably navigate over hundreds and sometimes even thousands of miles. In this first of two episodes, presenter Anand Jagatia travels to the Americas to meet the scientists finding and tracking these animals in order to solve the puzzle of where they go and why. Deep in the lush and noisy Belizean jungle, Anand joins avian biologist Abidas who is collecting data on the beautiful birds that visit tropical forests to escape harsh winters. Here, using misting nets, Abidas and her team carefully catch birds to measure their health and status before tagging and releasing them so they can continue stocking up on jungle food. Anand finds out why having long term data on migrant birds can help in understanding why some birds, like the wood thrush, have been declining in their native homes further north. Anand then jumps aboard a turtle boat in Florida where scientists from the Sea Turtle Conservancy have been collecting data on these dinosaur-like creatures. But finding them is harder it might seem. They move fast, so Anand accompanies the research team who are experienced in safely catching them, will he be lucky and find one of these magnificent creatures? Presented by Anand Jagatia and produced by Melanie Brown Contributors: David Barrie – Navigator & author Tim Guilford – University of Oxford Abidas Ash – University of Belize Kristen Ruegg - Colorado State University David Godfrey – Sea Turtle Conservancy [Image credit: BBC Staff, Melanie Brown]

Faced with one cake and eight hungry people, it’s pretty obvious how maths underpins reality. But as mathematics gets further from common sense and into seemingly abstract territory, nature still seems to obey its rules - whether in the orbit of a planet, the number of petals on a flower, or the structure of an atom. But what exactly is the relationship between mathematics and reality? That’s the impossibly difficult question CrowdScience has been set this week by our listener Sergio in Peru. It’s one that’s been pondered by humans for millennia: the Greek philosopher Pythagoras believed “All is number”. Is maths a human construct to help us make sense of reality - a tool, a model, a language? Does maths create its own reality? Or is it reality itself? CrowdScience explores these questions with the help of experts from the fields of philosophy, mathematics and science: Dr Eleanor Knox, Dr Eugenia Cheng, Professor Lucie Green, Alex Bellos and Stefano Centineo. Presenter: Marnie Chesterton Produced by Cathy Edwards for the BBC World Service (Photo: A young woman with her eyes closed standing in front of chalkboard, working out maths formulas. Credit: Getty Images)

Massage has been used for thousands of years to soothe our aches and pains and help us relax. Today there are a wide array of styles to choose from – Swedish massage, deep tissue, hot stone, sport, Thai, the list goes on. But which techniques are backed up by evidence? CrowdScience listeners Catherine and Stacy are keen for us to untangle this knotty issue, so presenter Caroline Steel selflessly ventures from her desk to the massage table all in the name of science. Is there such thing as a muscle 'knot' and can massage help to get rid of them? Does lactate build up in our muscles and need to be released? And why does rubbing sore muscles feel so good? We dig into the physiological and psychological aspects of what's happening in our bodies when we get a massage. With scientists only beginning to study massage in recent decades, we put the research to the test with our many questions and even a bit of myth-busting. Can massage help us avoid injury or recover faster when we exercise? Does drinking water after a massage flush out toxins? Is self-massage or massage from a friend or family member just as good as that from a professional massage therapist? Can children benefit from massage? Caroline talks to medical professionals and experts to find out what works when it comes to treating a stiff neck and tight muscles and unpacks the importance of touch in relieving the tensions of modern life. Presented by Caroline Steel and produced by Sam Baker for BBC World Service. Featuring: ● Cecillia Ljunggren, London School of Massage ● Mark Tarnopolsky, McMaster University ● Tiffany Field, Touch Research Institute, University of Miami Health System ● Wichai Eungpinichpong, Department of Physical Therapy, Khon Kaen University [Image credit: Getty Images]

If you took a fly into a really tall elevator and let it out at the top, would it still be able to fly? And what’s the absolute highest an insect could possibly go? It’s a question that’s been bugging CrowdScience listener Chee for a while, but presenter Alex Lathbridge is on the case. He discovers that when they’re not buzzing around your lunch, insects can be routinely found flying high up in the atmosphere travelling from A to B. There are also ground-dwelling bumblebees living in the mountains of Sichuan, China that have demonstrated an ability to fly at altitudes higher than the highest point on the planet. But leaving aside how high insects DO fly, how high COULD they fly if given the chance? Alex explores the theoretical limits of insect flight with the help of a bit of biomechanics – before contemplating the ultimate heights of the International Space Station where the mystery of whether a fruit fly will fly in zero gravity is finally answered. Contributors: Jason Chapman, University of Exeter Inés Dawson, science youtuber and expert in insect flight biomechanics Michael Dillon, University of Wyoming Wes Shaw, Head Gardener, Sky Garden Sharmila Bhattacharya, NASA Presented by Alex Lathbridge Produced by Ben Motley for the BBC World Service [Photop credit: Getty Images]

Controlling fire was a turning point in the development of human civilisation. But how did fire become part of the human toolkit? It's a question that has got Crowdscience listener Joseph wondering. He wants to know how humans first made fire and how that knowledge spread around the world, eventually developing into our industrial civilisations today. Archaeologists have many different ideas and theories about this. Did humans learn the skill millions of years ago, and carry it with them as they migrated out of what is now Africa? Or was it a skill developed much later, after different groups had settled in different locations? Did people share the skill with each other or did different groups of people discover it individually? Marnie Chesterton speaks to experts to try to piece together the archaeological clues to discover what kindled humankind's relationship with fire and flame. She hears about the early evidence of fire from Anand Jagatia, who visits Wonderwerk Cave in South Africa, and she speaks to an archaeologist who has found remains of burned flint suggesting campfire locations dating back hundreds of thousands of years in Israel. Marnie also tries her hand at making fire, Neanderthal style. Contributors: Dr Andrew Sorensen, Leiden University Prof Nira Alperson-Afil, Bar-Ilan University Prof Richard Wrangham, Harvard University Dr David Morris, McGregor Museum Candice Koopowitz, Simon Fraser University Dr Katharine MacDonald, Leiden University Presented by Marnie Chesterton and Produced by Hannah Fisher for BBC World Service Image Credit: Getty Images

How good are you at finding your way from A to B? Humans throughout history have used all sorts of tools to get us to our destination – from a trusty map and compass to the instant directions on a smartphone. But CrowdScience listener Pam from Florida wants to know what happens when we leave the surface of the Earth and try to navigate our way around space. Is there a North and South we can use to orientate ourselves? Which way is left if your nearest landmark is a million light years away? And if you can’t tell which way is up, how do spacecraft know where they’re going? Presenter Anand Jagatia speaks to experts in an attempt to find his way through the tricky problem of intergalactic space navigation. Contributors: Ethan Siegal, journalist and astrophysicist Michelle Baker, ESA Coryn Bailer-Jones, Max Planck Institute for Astronomy Presented by Anand Jagatia Produced by Caroline Steel for the BBC World Service

Climate change and biodiversity loss are two of the biggest threats humanity has ever faced - and tackling them is going to take a whole lot of collaboration and putting others before ourselves. But are humans cut out for this level of cooperation? Or are we fundamentally too self-interested to work together for the common good? Listener Divyesh is not very hopeful about all this, so he’s asked CrowdScience if humans have a “selfish gene” that dooms us to failure when trying to meet these challenges. He's worried that humans are destined by our evolution to consume ever more natural resources and destroy the environment in the process. But while it's true that humans often act in our own interest, we also show high levels of cooperation and care. Could tapping into these beneficial behaviours help us solve our global problems? Marnie Chesterton goes on the hunt for the best ways to harness human nature for the good of planet Earth - from making sure the green choice is always the cheaper and easier option, to encouraging and nurturing our better, altruistic and collaborative sides. We visit a rural mountain community in Spain to see the centuries-old system they have for sharing common resources; while in the city, we meet activists figuring out how to live a more community-spirited and sustainable urban life. And we speak to experts in evolution, ecology and psychology to find out what helps nudge us into greener habits. Presenter: Marnie Chesterton. Produced by Cathy Edwards for BBC World Service. Image Credit: Getty Images

How is a small budget pocket radio able to recreate all the atmosphere and sounds of a football match? CrowdScience listener Andy wants to know about the science enabling his radio listening, so presenter CrowdScience Geoff Marsh sets off - microphone in hand - to follow the journey of sound on the radio. Starting with the microphone, Geoff learns how acoustic energy is converted into electrical signals. Then BBC World Service presenter Gareth takes Geoff to a little-known room in the BBC called the Radio Shack. Gareth demonstrates how these electrical signals are attached to radio waves before being sent over the airwaves and they take a radio kit apart to understand how these waves are received and converted back into sound waves. Geoff talks to a speech and hearing specialist who, through the use of auditory illusions, shows Geoff that our brains are often filling in the gaps of lower quality audio. Finally, Geoff visits an acoustic lab at Salford University where he hears a demonstration of ‘object based audio’. This technology could enable us to create our own bespoke mix of dramas and sports, such as heightening the commentary sound or choosing to hear just the crowd, just by using the everyday speakers many have lying around them, such as mobile phones. Tune in and join us! Presented by Geoff Marsh Produced by Melanie Brown [Image Credit: Getty Images]

Scientists have been searching for dark matter for decades, and think there’s six times more of it in the universe than the stuff we can actually see, like stars and planets. But they still don’t know what it is. So how can we be sure dark matter really exists? And why does it matter, anyway? Back in 2018, armed with a boiler suit, hard hat and ear defenders, Marnie Chesterton travelled over a kilometre underground into a hot and sweaty mine to see how scientists are valiantly trying to catch some elusive particles – in the hope of settling things once and for all. Several years on we return to the problem, tackling a few more CrowdScience listeners’ questions about dark matter, and hearing whether we’re any closer to uncovering its mysteries. We’re joined in our quest by Dr Chanda Prescod-Weinstein, physicist and author of The Disordered Cosmos: A Journey into Dark Matter, Spacetime, and Dreams Deferred. With Professor Malcolm Fairbairn, Dr Chanda Prescod-Weinstein, Dr Chamkaur Ghag and Professor Katherine Freese. Presented by Marnie Chesterton Produced by Graihagh Jackson and Cathy Edwards

We live in a world where bigger is often seen as better - and the size of someone's brain is no exception. But a listener in Nairobi wants to know, does size really matter when it comes to grey matter? CrowdScience presenter Marnie Chesterton is on a mission to find out if the physical attributes of our head and brain can tell us anything about what's going on inside. We certainly thought so in the past. In the 1800s, phrenology – determining someone’s characteristics by their skull shape – was very fashionable and curator Malcolm MacCallum gives us a tour of the extensive phrenological collection of death masks and skulls in Edinburgh’s anatomy museum. It's a 'science' that's now been completely debunked. Yet there’s no escaping the fact that over our evolutionary history, human brain size has increased dramatically alongside our cognitive capabilities. But is it the whole story? Rick Potts, Director of the Human Origins Program at the Smithsonian tells of the point in time when human brains expanded the most; a time when the climate was changing, resources were unreliable and the intelligence to be adaptable might mean the difference between life and death. Adaptability is also key to Professor Wendy Johnson’s definition of intelligence, although she points out that IQ test, flawed as they are, are still the best predictor we have for intelligence… and that, yes, there is a weak correlation between having a larger head, and doing better at IQ tests. Why is that? We don’t know, says Dr Stuart Ritchie from KCL. According to him, neuroscientists are only in the foothills of understanding how a physical difference in the brain might underpin a person’s psychology. But researching this could offer valuable insights into how our amazing brains work. [Image: Brain being measured. Credit: Getty Images]

“I’m bored!” We can all relate to the uncomfortable - and at times unbearable - feeling of boredom. But what is it? Why does it happen? And could this frustrating, thumb-twiddling experience actually serve some evolutionary purpose? CrowdScience listener Brian started wondering this over a particularly uninspiring bowl of washing up, and it’s ended with Marnie Chesterton going on a blessedly un-boring tour through the science and psychology of tedium. She finds out why some people are more affected than others, why boredom is the key to discovery and innovation, and how we can all start improving our lives by embracing those mind-numbing moments. Featuring: Prof James Danckert (University of Waterloo, Canada), Dr Elizabeth Weybright (Washington State University), Dr Christian Chan (Hong Kong University) and Annie Runkel (University of Dundee). Presented by Marnie Chesterton Produced by Samara Linton Image: Young Asian girl feeling lonely and bored at home. Screen addiction withdrawal symptoms (Credit: Oscar Wong, Getty Images)

Should you wash your eggs? Well believe it or not, there is quite an international debate about this question from CrowdScience listener Susan. In Canada, where Susan grew up, commercially sold eggs are washed before they reach stores, whereas in the UK where she is now living they are not. So what is best to avoid contamination? It’s one of a number of egg-themed questions that CrowdScience tries to crack in this episode. One of our presenters, Marnie Chesterton, heads over to Susan’s home in London to cook some eggs and explore other egg cooking questions from our listeners, such as what is the science behind frying an egg without it sticking to the pan and why are some boiled eggs harder to shell than others? Meanwhile this episode’s other presenter, Anand Jagatia, explores questions about eggs after they have hatched. He investigates a case of curious chicken behaviour sent in by listener Laurie, as well as working out how a cuckoo knows it’s a cuckoo when it’s been raised in another bird’s nest. Presented by Marnie Chesterton and Anand Jagatia Produced by Jonathan Blackwell for BBC World Service Featuring: Dr. Vincent Guyonnet, Dr. Valérie Lechevalier, Dr. Siobhan Abeyesinghe and Dr. Ros Gloag (Photo credit: Getty Images)

Raindrops on roses and whiskers on kittens – CrowdScience has covered a lot this year. And what better way to see out 2021 than to look back at a few of our (and your!) favourite things? Great questions are right at the top of the team’s list – especially with the way that for every one we answer, five more appear in our inbox! So for a festive treat, Marnie asks the crew to answer three of them. What's the sun's role in our sense of direction? Why are we so uncomfortable with other people’s sadness? And why does listening to the radio make us sleepy? (Or is it just too much eggnog…?) From our favourite listener advice on how to keep your Christmas lights untangled to why cold swimming could activate your Vagus nerve, tune in for new questions and more CrowdScience favourites to light up your holiday season! Presented by Marnie Chesterton and many members the CrowdScience Team – Melanie Brown, Marijke Peters, Caroline Steel, Hannah Fisher, Samara Linton and Anand Jagatia. Produced by Sam Baker for BBC World Service. Featuring: • Haneul Jang, post-doctoral researcher, the Max Planck Institute for Evolutionary Anthropology • Juliet Rosenfeld, psychotherapist and author of The State of Disbelief: A Story of Death, Love and Forgetting • Mathias Basner, professor of psychiatry, University of Pennsylvania

As many of us gear up for the annual Christmas feast, some of you may be wondering how to eat everything before it goes off. It’s a great question, as the UN puts global food waste at a whopping 1.3 billion tonnes a year – that’s one third of all edible produce being thrown in the bin. So this week the team investigates listener Peter’s query about what makes some fruit and vegetables rot faster than others. Preserving food used to be about ensuring nomadic populations could keep moving without going hungry, but these days some things seem to have an almost indefinite shelf-life. Is it about better packaging or can clever chemistry help products stay better for longer? A Master Food Preserver explains how heat and cold help keep microbes at bay, and how fermentation encourages the growth of healthy bacteria which crowd out the ones that make us ill. Presenter Datshiane Navanayagam learns how to make a sauerkraut that could keep for weeks, and investigates the gases that food giants use to keep fruit and veg field-fresh. But as the industry searches for new techniques to stretch shelf-life even further could preservatives in food be affecting our microbiome? Research shows sulphites may be killing off ‘friendly’ gut bacteria linked to preventing conditions including cancer and Crohn’s disease. Produced by Marijke Peters for BBC World Service. Featuring: Christina Ward, Master Food Preserver Dr Heidy den Besten, Food Microbiologist, Wageningen University Ian Shuttlewood, Tilbury Cold Store Professor Sally Irwin, University of Hawaii

Life is full of choices, from the mundane (like what to wear today) to the critical (how should we deal with the pandemic?). So how can we make the best decisions? That’s what listener David wants to know. To investigate, Caroline Steel learns how being smarter doesn’t necessarily make you a good decision maker. She speaks to researchers about the importance of ‘gut feelings’ – and how certain people with no intuition whatsoever can struggle to make choices. She also learns why it’s easier to give advice to other people than to follow it yourself, and how we can work together to make the best decisions in a group. Presenter: Caroline Steel Producer: Anand Jagatia Contributors: Wändy Bruin de Bruin - Professor of Public Policy, Psychology and Behavioural Science, University of Southern California, USA David Robson, science journalist and author Valerie van Mulukom, Assistant Professor, Coventry University, UK Liz Steel Igor Grossmann, Associate Professor of psychology, University of Waterloo, Canada Anita Williams Woolley associate professor of organisational behaviour and theory, Carnegie Mellon University, USA

What makes things sticky? Listener Mitch from the USA began wondering while he was taking down some very sticky wallpaper. Our world would quite literally fall apart without adhesives. They are almost everywhere – in our buildings, in our cars and in our smartphones. But how do they hold things together? To find out, presenter Marnie Chesterton visits a luthier, Anette Fajardo, who uses animal glues every day in her job making violins. These glues have been used since the ancient Egyptians –but adhesives are much older than that. Marnie speaks to archaeologist Dr Geeske Langejans from Delft University of Technology about prehistoric glues made from birch bark, dated to 200,000 years ago. She goes to see a chemist, Prof Steven Abbott, who helps her understand why anything actually sticks to anything else. And she speaks to physicist Dr Ivan Vera-Marun at the University of Manchester, about the nanotechnologists using adhesion at tiny scales to make materials of the future. Presented by Marnie Chesterton. Produced by Anand Jagatia for BBC World Service This episode was originally broadcast on 2nd October 2020

In most cultures, the soundtrack to our lives is one of optimism. We are told to aim for the stars, dream big and believe that tomorrow will definitely be a better day. But why do so many people subscribe to the cult of 'glass half full' when life’s hardships should make any reasonable person a bit more wary? Listener Hannah from Germany - a self-described pessimist - is intrigued as to whether the optimistic way of life is really the best way to be. Taking on the challenge is Marnie Chesterton, who finds out why 80% of the population have an optimism bias and how the ability to hope and take risks may have helped the human species get where it is today. She also meets a man who pushes the optimistic outlook to its very limits - Base jumping world champion, Espen Fadnes. Listener Hannah on the other hand looks into the psychology of pessimism to find out if there are any advantages to her less rose-tinted view on life - and whether the culture we grow up in shapes how realistically we see the world. Producer: Caroline Steel Presentet: Marnie Chesterton Contributors: Espen Fadnes – Freefall professional Tali Sharot – Professor of neuroscience, UCL Julie Norem - Professor of psychology, Wellesley College Jeanne Tsai - Professor of psychology, Stanford (Image: Two arrows, one with a sad smiley and the other with happy smiley, pointing in opposite directions. Credit: Getty Images)

Cats started hanging out with humans thousands of years ago, and nowadays these fluffy, lovable pets are found in many of our homes. But there is no doubt lots of them still have keen hunting instincts - witness all the birds and small mammals they kill each year. CrowdScience listener Rachel started wondering whether her cat Eva could fend for herself while watching her uncoordinated swipes at a toy on a string, and seeing her fall off the sofa. Even though Eva was once a stray, she now lives entirely indoors, and it is hard to imagine her holding her own back on the mean streets. But could this pampered pet recover her survival instincts? Or would she go hungry, or fall foul of other cats or predators? Cat behaviour expert Roger Tabor is on hand with answers. His pioneering ‘cat-navs’ shine a light on what cats get up to inside and outside the home; we meet one of his subjects, a tiny cat with a fierce personality. Roger explains how a cat’s survival toolkit depends on their sex, breed, and above all their early life. Environment matters, too, so in Japan, where Rachel and her pet cat live, we visit a cat shelter to learn about the day-to-day challenges stray cats face. And just how ‘domestic’ are our cats, anyway? How different are they from their wildcat cousins, and how did they come to be our companions in the first place? It turns out beguiling humans might be even more of a survival trick than hunting. Presenter: Melanie Brown Producer: Cathy Edwards Contributors: Roger Tabor – Chartered Biologist and Cat Behaviourist Jamie Baker – Head Keeper, Battersea Park Children’s Zoo Dr Eva-Maria Geigl – Research Director, CNRS (French National Centre for Scientific Research) Susan Roberts and Cheryl Nodhturft-Mori – Japan Cat Network (Image: Cat in Lion costume. Credit: Getty Images)

Concrete is the most widely used substance on earth after water. It’s quite literally the foundation of the modern world, and no wonder - it’s strong, cheap, and mouldable into nearly any shape. But these benefits come at a cost: concrete production is responsible for around 8% of global CO2 emissions - that’s around three times more than the aviation industry. Concrete might not look pretty, but given its carbon footprint, should we be more careful about how we use it? And rather than throwing waste into landfill, could we recycle it instead? That’s what Crowdscience listener Catherine wants to know. To investigate, Marnie Chesterton and Anand Jagatia learn more about what makes concrete such a brilliant and versatile material. It’s down to the chemistry of how cement dries – which, it turns out, is anything but boring. They find out how the stuff is made, and why that produces so much carbon. And they hear about some ingenious projects to repurpose demolition waste – including creating underwater habitats for marine life, and using 3D printers to turn crushed concrete into street furniture. With Prof John Provis, Prof Becky Lunn, Chris LaPorta, Sheryl Lee, Dr Edward Randviir and David Lacy Presented by Marnie Chesterton and Anand Jagatia. Produced by Anand Jagatia for BBC World Service [Image: Discarded Concrete, Credit: Getty Images]

The science is unequivocal: human-made climate change is leading the world into an environmental crisis, and time is running out to prevent permanent damage to ecosystems and make the planet uninhabitable for many of us humans. As communities around the world increasingly experience the devastating effects of global warming, world leaders, policy makers and scientists from all over the globe are attending COP26, the United Nation’s major climate summit in Glasgow, Scotland. Each nation will be frantically negotiating its commitments to tackling emissions - many agree it’s a pivotal moment for the future of humanity. Crowdscience hosts a panel of three experts taking part in the conference, to hear their thoughts on what progress has been made so far. They answer listener questions on rising sea levels, explaining that a temperature rise of more than 1.5 degrees won’t just affect small island nations but will have serious consequences for every country in the world. We hear about an interactive atlas developed by the Intergovernmental Panel on Climate Change (IPCC) that shows the impact of higher temperatures in different regions. And presenter Marnie Chesterton asks about the financial barriers that have prevented many people from traveling to COP26 and discovers why it’s vital that people from the global south have their voices heard. Featuring: Ko Barrett, Vice-chair of the Intergovernmental Panel on Climate Change (IPCC) Dr Saleemul Huq, Director of the International Centre for Climate Change and Development in Bangladesh(ICCCAD) Dr Tara Shine, Director of Change By Degrees Produced by Melanie Brown and Marijke Peters for BBC World Service. [Image: Delegates in the Action Zone at COP26 UN Climate Summit, Glasgow. Credit: Getty Images]

As the world slowly moves away from using fossil fuels for electricity, one tiny Scottish island has proved it’s possible to rely almost entirely on renewables. The inner Hebridean isle of Eigg used to get its power from diesel generators. But in 2008 its residents launched the world’s first electricity system powered by nature, and the Crowdscience team wants to know exactly how they did it, and whether such a model could work in other places with no national grid? Marnie discovers that the community is key to the success of this project, meeting the maintenance men who taught themselves to install equipment and solve any problems themselves, and hearing from residents who’ve changed their habits to use less juice. With the mainland more than an hour away by a once-daily ferry, this kind of resourcefulness is vital. Hydroelectric generators harness the power of running water and are complemented by wind turbines and solar panels on peoples roofs, meeting 95% of Eigg’s energy needs. Now others are learning from this unique experiment and we meet the Malawians who were inspired after visiting Eigg. A solar grid in the village of Sitolo has provided power to thousands of people, and the people who designed it are planning others. Thanks to Eigg residents: Sue Hollands, Maggie Fyfe, Eddie Scott, Bob Wallace, Greg Carr Presented by Marnie Chesterton Produced by Marijke Peters for BBC World Service. This episode of CrowdScience has been edited to correct a factual error Image: Wind turbines on Eigg Credit: Getty Images

"To be or not to be” was never your decision. No one alive today is an “exister” by consent - your parents made that call for you. But who can blame them? Animals are hardwired with strong impulses towards their procreative goals, and we humans, by and large, are no different. But for some conscientious people alive today, this most fundamental of biological impulses is butting up against a rational pessimism about the future... With apocalyptic scenes of natural disasters, rising sea levels and global pandemics causing existential dread and actual suffering, it's understandable that CrowdScience listener Philine Hoven from Austria wrote to us asking for help her make sense of what she sees as the most difficult question she faces - should she have children? In this episode, presenter Geoff Marsh helps Philine to predict what kind of a world her hypothetical child might inhabit, and explores the impact their existence, or indeed non-existence might have on society and the planet. Plus, we'll explore what ‘antinatalism’- a philosophical stance which argues against procreation, can tell us about the moral landscape of the unborn. With Ms Caroline Hickman, Professor Mike Berners-Lee, Professor Noriko Tsuya and Professor David Benatar. Presented and produced by Geoff Marsh for BBC World Service

Philosophers have long pondered the concept of a brain in a jar, hooked up to a simulated world. Though this has largely remained a thought experiment, CrowdScience listener JP wants to know if it might become reality in the not-too-distant future, with advances in stem cell research. In the two decades since stem cell research began, scientists have learned how to use these cells to create the myriad of cell types in our bodies, including those in our brains, offering researchers ways to study neurological injuries and neurodegenerative disorders. Some labs have actually started 3D printing stem cells into sections of brain tissue in order to study specific interactions in the brain. Human brain organoids offer another way to study brain development and diseases from autism to the Zika virus. So, might stem cell research one day lead to a fully-grown human brain, or is that resolutely in the realm of science fiction? If something resembling our brains is on the horizon, is there any chance that it could actually become conscious? And how would we even know if it was? Host Marnie Chesterton takes a peek inside the human brain and speaks with leading scientists in the field, including a philosopher and ethicist who talks about the benefits – and potential pitfalls – of growing human brain models. Along the way, we'll pull apart the science from what still remains (at least for now) fiction. Presented by Marnie Chesterton Produced by Sam Baker for BBC World Service

Snails are a major enemy of gardeners around the world, invading vegetable patches and gobbling prize plants. CrowdScience listener Alexandre reckons he’s removed thousands of them from his garden, which got him wondering: apart from eating his garden to the core, what’s their wider role in nature? Would anyone or anything miss them if they suddenly disappeared? And for that matter, what about other creatures? We all know how complex biodiversity is, but it seems that some animals are more important than others in maintaining the balance of life on earth. Is there anything that could go extinct without having knock-on effects? CrowdScience heads to the Hawaiian mountains, a snail diversity hotspot, to discover the deep value of snails to native ecosystems there. Researchers and conservationists are working together to protect these highly endangered snails, and their natural habitats, from multiple threats. We hear why all snails – even the ones munching Alexandre’s petunias – have their role to play in the natural world, and get to grips with cascading extinctions: how the loss of a single species can trigger unpredictable effects on a whole ecosystem. With contributions from Imogen Cavadino, Dr Norine Yeung, Dr Kenneth Hayes, Dr David Sischo, Jan Kealoha, and Professor Ian Donohue. Presented by Marnie Chesterton Produced by Cathy Edwards for the BBC World Service [Image credit: Getty Images]

In the past 18 months we have heard lots about the human immune system, as we all learn about how our bodies fight off Covid-19 and how the vaccine helps protect us. But this got listener John, in Alberta, Canada, thinking about how trees and plants respond to diseases and threats. Do they have immune systems and if so, how do they work? Do they have memories that mean they can remember diseases or stressful events 5 months, or 5 years down the line, to be better prepared if they encounter the same threats again? Presenter Marnie Chesterton sets out to investigate the inner workings of plants and trees, discovering that plants not only have a sophisticated immune system, but that they can use that immune system to warn their neighbours of an attack. Some researchers are also investigating how we can help plants, especially crops, have better immune systems – whether that’s by vaccination or by editing their genes to make their immune systems more efficient. But some plants, like trees, live for a really long time. How long can they remember any attacks for? Can they pass any of those memories on to their offspring? Crowdscience visits one experimental forest where they are simulating the future CO2 levels of 2050 to understand how trees will react to climate change. Featuring: Professor Jurriaan Ton, University of Sheffield Professor Xinnian Dong, Duke University Dr Estrella Luna-Diez, University of Birmingham Peter Miles, F.A.C.E. Facility Technician, University of Birmingham Presented by Marnie Chesterton and Produced by Hannah Fisher for the BBC World Service. Photo credit: Getty Images

This year has been a weird one for UK gardeners – unpredictable spring temperatures meant flowers failed to bloom and throughout the rainy summer, slugs have been savaging salad crops. But why and when plants blossom is about more than just early cold spells and wet weather, and a listener in California has asked Crowdscience to investigate. Flowering is vital to both plants and us. Without it, they wouldn’t be able to evolve and survive (and we wouldn’t have anything to eat). Anand Jagatia hears that different species have developed different strategies for doing this based on all sorts of things, from where they’re located to how big they are to what kind of insects are around to pollinate them. The famously stinky Titan Arum, or corpse flower, for example, blooms for a single day once every decade or so before collapsing on itself and becoming dormant again. This gives it the best chance of attracting carrion beetles in the steamy Sumatran jungle. But other plants open their petals much more regularly, which is a process regulated by a clever internal clock that can sense daylight and night. It’s even possible to trick some of them into producing flowers out of season. Cold is also a vital step for some brassicas and trees, and scientists are starting to understand the genes involved. But as climate change makes winters in parts of the world warmer and shorter, there are worrying knock on effects for our food supply. Produced by Marijke Peters for BBC World Service. Featuring: Guy Barter, RHS Professor Judy Jernstedt, UC Davis Professor Dame Caroline Dean, John Innes Centre Professor Ove Nilsson, Umea Plant Science Centre (Photo credit: Getty Images)

Look into my eyes. What do you see? Pupil, lens, retina… an intricate set of special tissues and mechanisms all working seamlessly together, so that I can see the world around me. Charles Darwin called the eye an ‘organ of extreme perfection’ and he’s not wrong! But if the eye is so complex and intricate, how did it evolve? One listener, Aloyce from Tanzania, got in touch to pose this difficult question. It’s a question that taxed Darwin himself, but CrowdScience is always up for a challenge! The problem is that eyes weren’t ever designed - they were cobbled together over millions and millions of years, formed gradually by the tweaks and adaptations of evolution. How do you get from the basic detection of light to the wonderful complexity - and diversity – of visual systems we find throughout the animal kingdom? CrowdScience sent Marnie Chesterton on an 800 million year journey to trace how the different elements that make up the human eye gradually came into being; from the emergence of the first light-sensitive proteins to crude eye-cups, from deep sea creatures with simple pinhole eyes to the first light-focusing lenses, all the way to the technicolour detail of the present day. Produced by Ilan Goodman for the BBC World Service. With contributions from: Dr Adam Rutherford, Dr Megan Porter, Professor Dan Nilsson, Dr Samantha Strong (Photo Credit: Getty Images)

Pioneering physicist and inventor Nikolas Tesla dreamt of connecting the world up through wireless communication and power. Despite demonstrating he could transfer power short distances his longer distance experiments were considerably less successful. But CrowdScience listener, George from Ghana, wants to know if now - more than one hundred years after Tesla’s demonstrations - his dream of wireless power is closer to becoming a reality. In countries where rugged landscapes make laying traditional power lines difficult and costly, could wireless electricity help connect those communities who are without mains power? CrowdScience presenter Melanie Brown beams to reporters around the world who visit scientists now using state of the art technology to reimagine Tesla’s dream. Alex Lathbridge is in Ghana and after meeting listener George he gently doorsteps a local electrical engineering lecturer to find out how electricity can ‘jump’ between two coils. Reporter Stacy Knott visits start-up company EMROD in New Zealand who are developing ‘beamable’ electricity. She hears an electric guitar being powered from 36 metres away with no wires and finds out how they are using lasers to make sure they don’t harm any wildlife that might wander into the beam. We then hear how wireless electricity could help fulfil the power demands of a growing electric vehicle market. Reporter John Ryan visits the town of Wenatchee where it has been electrifying its’ bus fleet and putting wireless chargers into the tarmac at bus-stops so that the busses can trickle charge as passengers get on and off. Finally, we ask whether one day, the tangled knot of wires spilling out of our electronic devices will be but a thing of the past. Presented and Produced by Melanie Brown with additional reporting from; Alex Lathbridge, John Ryan and Stacey Knott With contributions from; Prof. Bernard Carlson, Dr Samuel Afoakwa, Ray Simkin, Greg Kushnier, Andy Daga and Richard DeRock (Photo credit: Getty Images)

Our connection to the night sky spans cultures and millennia: observing the stars and planets helped our ancestors navigate the world, tell stories about the constellations, and understand our place in the universe. But these days, for the vast majority of us, seeing the stars is getting harder. 80% of people live under light polluted skies, and in many cities you’re lucky to see a handful of stars at night. This state of affairs is bothering CrowdScience listener and keen stargazer Mo from Salt Lake City in the USA, who wonders if there’s anything we can do about light pollution. Of course, we could simply turn out all the lights, but that’s unrealistic. So what are smarter ways of lighting our communities to preserve our view of the cosmos? Increasingly worried by the effect of artificial lighting on the ability to observe stars, astronomer Dr Jason Pun set up a series of monitoring stations to continuously measure ‘sky glow’. By comparing sky glow across the world, he wants to figure out which approaches work best. One community taking an active approach is the South Downs National Park in South East England, one of a number of Dark Sky Reserves around the word. We visit the park and speak to the Dark Skies Officer there, to find out how people are coming together to turn down their lights and keep the night dark. And it’s not just stargazing that’s threatened by light pollution. Artificial light at night disrupts the circadian rhythms of wildlife. We visit a project in rural Germany looking into the benefits of dark-sky-friendly lighting on insect populations there. With contributions from Dr Jason Pun, Paulina Villalobos, Dan Oakley, Doug Jones, Dr Sibylle Schroer and Sophia Dehn. Presented by Anand Jagatia with additional reporting by Felix Franz Produced by Cathy Edwards [Image credit: Getty Images]

How we sleep is a topic of endless fascination and for some can, ironically be quite exhausting. Modern life has allowed us to invade the night, and those pesky late night work emails, social media and TV all conspire to limit our sleep or simply prevent us from a truly restful night. But if we travel back in time, did our ancestors master sleep any better? No air-con or electric fan for them on hot humid nights, and only smoky fires to keep them warm on cold, snowy nights. What if we go way back into our pre-history, to our ancient human ancestors? No interruption for them from an unwanted work email, however perhaps a ravenous lion gave them more reason for those night time worries. CrowdScience listener Tom asks our sleep deprived presenter Datshiane Navanayagam to investigate how our sleep has changed over history and pre-history. She talks to Professor Russell Foster, Head of the Sleep and Circadian Neuroscience Institute at the University of Oxford and Neanderthal expert Dr Rebecca Wragg Sykes about slumber habits in days of yore, and in doing so, she uncovers some top tips from our ancestors that may give us all a better nights rest. Presented by Datshiane Navanayagam and Produced by Alexandra Feachem (Woman sitting in bed and yawning. Credit: JGI/Jamie Grill/Getty Images)

If you’ve ever fallen over and grazed your skin, maybe you wished it were made of stronger stuff. The tough hide of a rhinoceros or the protective armour of a stag beetle would do a better job. It’s a thought that’s been bothering CrowdScience listener Paul, who points out that our skin also suffers from acne, eczema and hives; it dries out; it bruises. In fact, human hide is so vulnerable that we cover our feet in other animals’ skin and our bodies in clothes just to make life more comfortable. Is this really the pinnacle of evolution? Marnie Chesterton makes the case for the largest, fastest-growing organ, hiding in plain site on our body. Tissue Engineer Professor Sheila MacNeil from Sheffield University explains how skin manages to be breathable yet waterproof; flexible yet stronger than steel; sensitive to touch but protective against pollution and damaging UV. Skin biologist Dr Christina Philippeos from King’s College London explains how our bodies make a scar. Professor Muzlifah Haniffa has developed an atlas of the human skin – a tool to help researchers unravel the mysteries of how different skin cells interact. This atlas should help treat skin diseases in the future. Over in Tanzania’s Regional Dermatology Training Centre in Moshi, Dr Daudi Mavura talks us through a rare but devastating skin disorder called Xeroderma Pigmentosum, or XP. For children with XP, sunlight is dangerous because a mutation in the skin’s DNA repair mechanism means that UV rays can cause lesions and tumours. Our epidermis is already multifunctional but over at Ben May Department of Cancer Research at the University of Chicago, Professor Xaioyang Wu and colleagues are looking at how much more skin could do. Personalised skin grafts may provide living drug patches to help people manage their disease, addiction or even weight. With thanks to Dr Lynne MacTavish from Mankwe Wildlife Reserve in South Africa for describing a rhino’s skin. Produced and presented by Marnie Chesterton. [Image: Young and Old, dry skin Credit: Eric A. Nelson/Getty Images]

Humans are responsible for emitting over 40 billion tonnes of carbon dioxide into the atmosphere every year – and we all know that we need to reduce that figure to prevent devastating climate change. Listener Saugat wonders whether smart technology and artificial intelligence can help us do this more quickly? Green energy will go a long way to tackling the problem, but integrating wind and solar into our current electricity grid is complicated. CrowdScience hears how AI is being used at a wind farm on the island of Orkney to predict periods of high winds, so that excess energy can be turned into hydrogen and stored, then converted back to electricity when there’s greater demand. Digital mirrors are also playing a major role in optimising performance, and scientists say cloud-based “twins” of physical assets like turbines can improve yield by up to 20%, allowing engineers to identify problems via computer without ever having to be on site. Marnie visits an intelligent building in London’s financial district where sensors control everything from air-conditioning to lighting, and machine learning means the building knows which staff will be on which floor at any given time, switching off lifts that are not in use and adjusting ventilation to save on power. Its designer says incorporating this kind of digital technology will help companies achieve net zero more quickly. And in India, more than half the population are involved in agriculture, but the sector is plagued by inefficiency and waste. Tech start-ups have realised there’s potential for growth, and are using drones to monitor crop production and spraying, giving farmers apps which help them decide when and where to fertilise their fields. Produced by Marijke Peters for BBC World Service. Featuring: Professor Srinivasan Keshav, University of Cambridge Matthew Marson, Arcadis Group [Image Credit: Getty Images]

Today, up to 3 billion people around the world play video games, from candy based mobile puzzles to virtual battlegrounds filled with weapons. Many people have turned to gaming during the pandemic as a way of staying connected – but what does science really say about the impact of gaming? Does playing violent video games lead to violence in the real world? Do brain training apps really work? How much gaming is too much – can videogames really be addictive? And how can videogames help us to explore difficult issues like death, grief and loss? Alex Lathbridge and Anand Jagatia look at the evidence and play some games along the way, speaking to psychologists, doctors and game designers about the power of video games to change us - for better or worse. With Adrian Hon, Professor Andrew Przybylski, Professor Pete Etchells, Professor Henrietta Bowden-Jones and Dr Sabine Harrer

Reduce, Reuse, Recycle. It’s a well-known phrase that we all try and follow in our day to day lives. But are our current recycling habits the best they can be? It’s a hot topic at Crowdscience - multiple listeners have contacted Crowdscience with questions about the ins and outs of recycling. We follow one listener’s food waste to a processing plant to investigate whether or not it could be processed in our own homes. But aside from the food waste, what about the containers it comes in? We investigate if food containers really need to be cleaned before we put them in recycling bins, or if that just wastes water. Recycling processes differ all over the world, so we hear from reporter Chhavi Sachdev in Mumbai, India, who follows her plastic waste to find out how plastic sorting and recycling is a whole economy of its own. But new technologies have meant that biodegradable and bioderived plastics are starting to appear in our packaging, and one Crowdscience listener wants to know which is better for the environment – traditional plastic that has been recycled, or bioplastic and compostable alternatives? And looking to the future, could we ever recycle our plastic waste at home and use 3D printers to make useful things out of our own waste? Marnie Chesterton delves into these questions with Circular Economy Project Manager Dr Rhiannon Hunt of Manchester Metropolitan University, to discover the details of recycling and unearth how we can make our own recycling as efficient as possible. With Dave Atkins, reporter Chhavi Sachdev and Dr Rhiannon Hunt. Presented by Marnie Chesterton and Produced by Hannah Fisher for the BBC World Service. [Image credit; Getty Images]

One CrowdScience listener finds herself unconcerned about much of the world’s problems, it leaves her wondering: am I a psychopath? Inspired by a previous episode on empathy, this listener asked is it true that psychopaths don’t empathise and what are the character traits of psychopathy? Marnie Chesterton talks with a diagnosed pro-social psychopath to find out. She also pays a visit to the Netherlands Institute for Neuroscience and gets into an MRI scanner to discover what is happening in her brain when she empathises. Studies suggest around 1 percent of the general population exhibit traits associated with psychopathy and that rises to 3-4 percent in the world of business. But is this really the case? Why is there so much stigma associated with psychopathy and do psychopaths even exist or is it just a convenient term to label those whose emotional range sits outside of the “norm”? Presented by Marnie Chesterton and produced by Caroline Steel for the BBC World Service. Guests: Julia Shaw Jim Fallon Valeria Gazzola Kalliopi Ioumpa [Image credit: Getty Images]

Anyone who has ever taken the Christmas lights out of the cupboard, only to discover they’re hopelessly tangled, will sympathise with this week’s listener Eric. He has a 45m garden hose that always seems to snarl up and snag when he waters his garden, and he wonders what he’s doing wrong? Marnie starts by discovering the important difference between tangles and knots, as she scales a cliff with an experienced climber who explains the way you tie rope is a matter of life and death. Physicists are also fascinated in how string becomes jumbled up and one man has even won an IgNobel award for his work in this field. Doug E Smith discovered that if you put a piece of string in a box then spin it around, its length, thickness and how long you shake the box for, all determine whether it will tie itself up. Not only that, the more the string becomes twisted, the more likely it is to cross over itself and become impossible to untangle. While tangles might be annoying in hair or cables, they’re also a fundamental part of human life. Our DNA is constantly folding itself to fit inside tiny spaces – there are two metres of the stuff inside every cell, where it’s packed down tightly, before it must untangle and duplicate for those cells to divide. It does this with the help of specific enzymes, and when the process goes wrong it leads to cell death. But scientists are also studying molecular tangles that might benefit us humans, and creating nano-sized knots that can be turned into nets or meshes with incredible properties. Producer: Ilan Goodman Presenter: Marnie Chesterton

Standing takes less energy than walking, so why does it feel more tiring? At least, it does for CrowdScience listener Nina. She can march for hours without getting tired, but her legs and feet get achy after just a short time standing still. It’s one of three walking-themed questions CrowdScience is tackling this week. Taking inspiration from our active listeners, Marnie Chesterton walks up a hill with Caroline Williams, author of a new book about why humans are designed to move. We find out how our whole system – body and brain – works better when we’re walking, compared to standing still. We’re probably set up this way because of our evolutionary history: hunting and gathering needed us to be ‘cognitively engaged endurance athletes’. We stop for a break.. but is it true that we shouldn’t sit down to rest during a walk? Our listener Sarah is a keen hillwalker but likes to take the weight off her feet every now and again. Her hillwalking friends disapprove, saying she should rest on her feet. Is this a myth CrowdScience can bust? And finally a question from listener Matteo: is walking or running better for your health? Numerous studies show significant benefits to both forms of exercise, but in the end, the best kind of exercise is the one you’re motivated to do. With Caroline Williams, Dr François-Xavier Li, Professor Dick Greene and Professor Duck-Chul Lee.

Food. For all of us it is a basic necessity and for those lucky enough, it is something we spend a lot of time planning and enjoying. CrowdScience listeners certainly have a lot of food related questions; in this buffet of an episode Marnie Chesterton opens the fridge door to pick the tastiest. Starting with the seemingly simple question of what makes us feel hungry, and ending in outer-space, Marnie investigates flavour, nutrition and digestion. After a year when watching TV has become a core activity for many people stuck in their homes, one listener wants us to find out if eating food whilst watching the TV affects our perception of taste. We then journey to the skies and ask if it is true that food tastes blander on aeroplanes, what does that mean for astronauts’ mealtimes? Back on earth, Marnie explores whether humans are the only animals that season their food. Tuck in your napkins and prepare to feast on a smorgasbord of scientific snacks. Presented by Marnie Chesterton and Produced by Melanie Brown and Hannah Fisher for the BBC World Service. Guests: Professor Charles Spence Dr Kristine Beaulieu Mr. Takashi Funahashi Ruben Meerman Chef Jozef Youseff

It took a while before it was officially recognised as a major symptom of Covid-19, but loss of smell has affected up to 60 percent of people who have had the virus. And for a significant portion, smell continues to be an issue for weeks or months after their recovery. So what’s going on and how can you get your sense of smell back? We tend to think of our sense of smell as something universal – if it smells bad to me, it probably does to you but that is not the case for CrowdScience listener Annabel, who wonders why things other people love to sniff, she finds disgusting. Anand Jagatia investigates the science of smell, gets up close to the world’s smelliest plant and finds out if smell training can help those with long-term issues after Covid. Contributors Ellie Byondin, supervisor of the Princess of Wales Conservatory at London’s Kew Gardens Thomas Hummel, University of Dresden Carl Philpott, from the UK’s Norwich Medical School Sissel Tolaas, artist and smell historian based in Berlin Noam Sobel, Weizmann institute of science Presented by Anand Jagatia and Produced by Marijke Peters for the BBC World Service

Scales don’t come planet-sized, so answering a question from David in Ghana may require some ingenuity, after all, calculating the weight of the Earth is a huge task. Using a set of weighing scales and a 400 year-old equation, Marnie Chesterton attempts to find out just how much the Earth weighs and is it getting heavier or lighter over time? But how would a planet gain or lose mass? Which tips the scales: meteorites falling from space or gases constantly escaping from our atmosphere? And does the answer have any implications for the future of Earth? Could the atmosphere eventually run out? Contributors: Anuradha TK, former project director at ISRO Matt Genge, geologist at Imperial College London Jon Larsen, researcher at the University of Oslo Anjali Tripathi, astrophysicist Ethan Seigel, journalist and astrophysicist Presented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service. [Image: Earth on scales. Credit: Getty Images]

They say life is sweet. Well that’s certainly the case for CrowdScience listener Trevor in Poland who wonders why he can’t stop reaching for the cookie jar. He grew up drinking fruit juice with added sugar but wonders whether his genes could be as important as his environment when it comes to his sweet tooth, especially since his wife seem to be satisfied with mainly savoury snacks. The World Health Organisation says added sugar should constitute a maximum of 5% of our daily energy intake because it can contribute to diabetes, heart disease and obesity. But that’s tricky when you consider it’s now in everything from salad dressings, to savoury sauces. Manufacturers have been promoting sugar alternatives for decades but recreating the unique taste and feel of it in the mouth are a challenge. Marnie Chesterton gets to try a brand new innovation – a so-called ‘rare’ sugar that has 70 percent of the sweetness but almost none of the calories. In nature, allulose is found in figs, but one producer has discovered a way to make it in the lab. Does it taste as good as it claims? Whilst switching to alternative sugars and sweeteners may reduce the calories, some researchers claim that tasting sweetness, wherever it comes from, can disrupt the body’s mechanism for regulating blood-sugar levels, increasing the risk for conditions like diabetes. Presented by Marnie Chesterton and produced by Marijke Peters for the BBC World Service

It's a topic that's taboo in many cultures, yet it's also something nearly every woman experiences – on average upwards of 400 times throughout her life: menstruation. Responding to a flood of questions from our CrowdScience listeners, Marnie Chesterton seeks to unpack how periods affect women physically, mentally and societally. Why did humans evolve to have periods when fewer than two percent of mammals share our experience of menstrual cycles? Is it really a good use of our limited energy reserves? What can the little Egyptian spiny mouse teach us about PMS symptoms? We hear why periods may reduce the number of faulty embryos that implant and how more menstrual cycles may even increase our chances of developing certain types of cancer. Finally, as the number of periods a woman has over the course of her life has more than quadrupled since the pre-industrial era, Marnie asks: Do we really still need to have them? Contributors: Dr Nadia Bellofiore, Hudson Institute of Medical Research at Monash University Dr Deena Emera, Buck Institute Lameck Kiula, Jambo for Development Sally King, Menstrual Matters & King's College London Dr Diana Mansour, New Croft Centre & Newcastle University Presented by Marnie Chesterton Produced by Sam Baker and Melanie Brown for the BBC World Service

As millions more of us move to live in densely populated cities, we almost inevitably face living in closer proximity to our neighbours. Neighbour noise can certainly be a source of annoyance – but could it even be damaging to our health? Increasing evidence suggests that unwanted noise can cause sleep deprivation, distraction and annoyance, as presenter Anand Jagatia finds out. He discovers that noise annoyance has a small but significant impact on our wider health – including our cardiovascular system – but that annoyance is not necessarily down to sound alone. Factors such as perception of the neighbourhood and relationships with our neighbours also play a part. CrowdScience has examined living with unwanted noises before, and we revisit our trip to the acoustics lab at the University of Salford in Manchester, UK. Here, we meet the researchers and engineers investigating the best ways to make our homes more pleasant for our ears whilst still maintaining the ‘buzz’ of city life. Contributors: Contributors: Professor Charlotte Clark, St George’s University of London Professor Trevor Cox, University of Salford Manchester Professor Bill Davies, University of Salford Manchester Dr Mags Adams, University of Central Lancashire (formerly University of Salford Manchester, at time of recording) Produced by Jen Whyntie and presented by Anand Jagatia for the BBC World Service.

You are a star. Literally. You are a carbon-based life form and those atoms of carbon in the molecules that make up your cells were formed by a nuclear fusion reaction at the heart of long dead stars. That goes for the oxygen in your lungs too. And the red blood cells that carry that oxygen to your tissues? They contain haemoglobin, and nestled at the heart of each molecule is an element (iron) formed by a supernova - the fiery explosion at the death of a star. Your body is a walking, thinking museum of some of the most violent events in the universe. This, as CrowdScience host Marnie Chesterton discovers, isn’t as special as it sounds. All of the stuff on the earth - the elements that make clouds and mountains and mobile phones – they all have an origin story. CrowdScience tells that story, starting with the big bang and ending with physicists, creating new elements in the lab. Find out the age of the elements and the distance they have travelled to make their current home on earth. Interviewees: Dr Dorota Grabowska, Professor Andrea Sella, Dr Chris Pearson, Dr Jacklyn Gates (Photo: Neutron star. Credit: Getty Images)

There are over 400,000 species of plant on earth, they’re on every continent including Antarctica. But humans only regularly eat about 200 species globally, with the vast majority of our nutrition coming from just three species. Many of the fruits, leaves and tubers that other plants grow are packed full of toxins that are poisonous to us, and would make us very ill if we ate them. But could we take out the poisons and create new, edible crops? That’s what CrowdScience listener Marija wants to know. Crowdscience dives into this topic, and uncovers the that many crops are poisonous, and why so few plants are eaten globally. Host Anand Jagatia finds that even the modern scientific processes of crop breeding are very slow. But science can now engineer plants at the genetic level by adding, silencing or removing specific genes. This ‘genetic modification’ is hugely controversial but can be highly effective. Anand finds a man who has spent decades making cotton seeds edible by removing the poisons they naturally produce in their seeds. This GM crop could help fend-off starvation. But sometimes introducing poisons can be as important as removing them, as we find in the genetically modified ‘BT eggplants’ in Bangladesh. The new gene makes the vegetable toxic to a major insect pest, so they are much easier to grow. But GM crops are not the perfect solution. They have problems of gene escape, can increase the use of environmentally damaging herbicide, and can be open to monopolisation. In some countries, particularly in Europe, GM crops are hugely controversial. Anand finds out whether these concerns stand up to science and looks at the counterpoint in developing countries in Africa, South Asia and elsewhere, where local farmers like Patience Koku in Nigeria have little time for some of the concerns around GM, particularly as they see poor harvests, poverty and starvation as the more pressing problems. Contributors: Professor Sandra Knapp, The Natural History Museum in London Professor Julie King, Nottingham University Professor Keerti Rathore, Texas A&M University Dr Yousuf Akhond, Bangladesh Agricultural Research Institute Professor Matthew Cobb, University of Manchester Patience Koku, Nigerian Farmer and member of the Global Farmer’s Network Alliance for Science Produced by Rory Galloway and presented by Anand Jagatia for the BBC World Service. Image: Farmer with Fruits. Credit: Arif Hossain, Farming Future Bangladesh.

Have you taken classes to learn a new sport or musical instrument or a language? It’s hard work! Why is it that as children we effortlessly absorb new skills and we don’t as adults? That’s what 50-something listener Gary Grief wondered about playing guitar. Do you need to play more frequently as an adult to attain the same level of expertise? Does the 10,000-hours theory still apply? Presenter and budding tabla-player Anand Jagatia embarks on a musical journey to discover what neuroscience can tell us about muscle memory and learning. Do musicians and sportsmen share the same challenges? By understanding what’s happening in the brain, can we learn how to learn better? With tabla-teacher Satvinder Sehmbey, neuroscientist Dr Jessica Grahn, viola-player Dr Molly Gebrian and sports scientist Prof Yannis Pitsiladis. Presented by Anand Jagatia Produced by Dom Byrne for the BBC World Service [Image: Adult and Child learning Piano. Credit: Getty Images]

When eating a blackberry one day, CrowdScience listener Charles got a tiny seed stuck in his teeth. That got him wondering: why are seeds the size they are? Why does a blackberry have dozens of tiny pips, while a peach has one huge stone right in the middle? Plant seeds have been around for hundreds of millions of years, so they’ve had plenty of time to shapeshift into wildly different forms: from dust-like orchid seeds to giant coconuts. This evolution has been a long and intricate dance with wind, water and animals; we ask how different kinds of seeds might respond to today’s environmental threats and rapidly changing ecosystems. And we go in search of the world’s biggest seed, the coco de mer: native to just two remote islands in the Indian Ocean and weighing up to 18kg, how did this seed evolve to be so much bigger than any other? With Professor Angela Moles, Dr Si-Chong Chen, Marc Jean-Baptiste, Dr Frauke Fleischer-Dogley and Dr Wolfgang Stuppy. Presented by Marnie Chesterton Produced by Cathy Edwards for the BBC World Service [Photo: Different sized fruit seeds. Credit: Getty Images]

Most of us don’t like to dwell on our toilet habits, but this week Crowdscience has gone down the drain to discover what wastewater can tell us about our health. It’s been more than a year since scientists across the globe started to track the spread of Covid-19, with help from home test results and hospital data. Marnie Chesterton investigates the latest tool in their arsenal: sewage. Listener Kevin has heard how human waste can be monitored to check for virus levels, and wants to know if it can also be used to stop the disease in its tracks? Although the coronavirus has been discovered in people’s poo, so far there’s little indication it’s actually being spread through the water system. But by taking regular samples from different parts of cities, authorities are now able to accurately predict a local peak weeks before the population shows signs of sickness, then take immediate measures to alert them. In Detroit we hear how environmental engineer Professor Irene Xagoraraki used this method to detect a rare strain of Herpes which doctors didn’t even know was a potential problem. Marnie also talks to Professor Nick Thomson from the Wellcome Sanger Institute, who sequenced the genome of the bacteria that causes cholera, to understand how it has crisscrossed the globe. He discovered that the pandemic currently devastating Yemen actually originated in Asia. It’s a discovery that has changed how the WHO is thinking about this killer disease and could have important implications for vaccination programmes. But our effluent can also pose environmental problems, and Professor Andrew Johnson from the UK’s Centre for Ecology and Hydrology explains there are now as many as 300,000 chemicals that could threaten natural habitats. While authorities try to test each one individually, he’s concerned they may have different effects when they mix in wastewater, and current monitoring systems don’t take this into account. Not only that, but some of these substances contain silver nanoparticles, which Professor Juliane Filser tells us stick around in soil for ever, threatening organisms and bacteria at the base of the food chain. Presented by Marnie Chesterton and Produced by Marijke Peters for the BBC World Service. [Image: Sewage outlets. Credit: Getty Images]

Grief is universal. It is something almost all of us will go through at some point. And it is something that the people we love will experience when we die. Grief can be all consuming, it can make everyday tasks like getting out of bed, feel impossible. Which makes listener Oliver from Australia wonder - what is the point? It doesn’t bring what we lost, back. Why have we evolved to be so affected by loss? Be it the death of a loved one, the end of a relationship or the loss of a job. Does it serve any purpose? Or perhaps it is just the price we pay for being a social species with such strong connections. Image: Families Mourn Victims of The Tamaulipas Massacre in Tuilelén, Guatemala Photo by Josue Decavele/Getty Images Produced by Caroline Steel and presented by Marnie Chesterton for BBC World Service.

Gossip often has negative connotations, but does it get a bad rap? Might it serve a useful function and should we think of gossiping as an advanced social skill rather than a personality defect? CrowdScience listener Jayogi thinks it might be useful, and has asked CrowdScience to dig into the reasons why we find it so hard to resist salacious stories. Presenter Datshiane Navanayagam meets a scientist who views gossip as a key evolutionary adaption - as humans started to live in bigger cooperative groups, gossiping was a way of bonding and establishing acceptable group behaviour as well as cementing reputations of trustworthiness. Datshiane heads to the local park to catch some real gossiping in action and finds out that whilst people like to gossip they don’t consider themselves gossipers. Datshi asks a team of scientists what information we are most keen to share and glean in these interactions and if there is such a thing as ‘good’ and ‘bad’ gossip. She hears that in some group settings – like in the workplace - gossip can enhance cooperation and limit free-riders, but that it can also have a more self-serving dark side. Datshiane finds out if our stone-age gossipy minds are fit to operate in the world of mass communication and social media – is our fixation on celebrities related to our being hard wired to gossip? Presenter: Datshiane Navanayagam Producer: Melanie Brown [Image: Gossiping people. Credit: Getty Images]

If a tree falls in a forest, and no-one is there to hear it, does it make a sound? This is an age-old debate that listener Richard and his family have been arguing about for years. Can CrowdScience settle it once and for all? Caroline Steel speaks to experts in hearing, biology, philosophy, physics and sound design, which takes her to some unexpected places. Professor Stefan Bleek is an expert in psychoacoustics who says that sounds only exist in our heads. Dr Eleanor Knox and Dr Bryan Roberts are philosophers that make her question if anything exists outside our own perception. Professor Lilach Hadany wonders if it’s limited to humans and animals - could other plants hear the falling tree too? And Mat Eric Hart is a sound designer who says that sound is subjective – it’s always tangled up with our own interpretations. Things get truly weird as we delve into the strange implications of quantum physics. If there is such a thing as reality, doesn’t it change when we’re there to observe it? Does the tree even fall if we aren’t there? Presenter: Caroline Steel Producer: Anand Jagatia (Image: Fallen Tree. Credit: Getty Images)

Animals experience all the colds, stomach pains, headaches, parasites, and general illnesses that humans do. But unlike us, animals can’t just grab a painkiller off the shelf at the supermarket to cure it. They don’t have a pharmacy to browse… or at least, not the sort that we’d recognise. Listener Andrew Chen got in touch to ask whether animals use any kind of medicine themselves. After all, our own drugs largely come from the plants and minerals found in wild habitats. So perhaps animals themselves are using medicines they find in nature. Presenter Anand Jagatia speaks with the primate researcher who stumbled across a chimp chewing on a bitter leaf 35 years ago, Professor Mike Huffman, whose observations opened up a whole new field of research. We discover why plants contain the medicinal compounds they do, and how butterflies with brains no bigger than a pin-head are still able to select and use medicine to protect their young. We think of medicine as a human invention - but it turns out that we’ve learnt a lot of what we know from copying the birds, bugs and beasts. Presented by Anand Jagatia Produced by Rory Galloway Image: Chimp eating. Credit: Getty Images

The space industry, with its fuel-burning rockets, requirements for mined metals and inevitable production of space junk, is not currently renowned for its environmental credentials. Can space exploration ever be truly environmentally friendly? Presenter Marnie Chesterton answers a selection of listeners’ questions on the topic of space environmentalism. She starts by examining the carbon footprint of spaceship manufacturing here on Earth, and asking whether reusable rocket ships such as Space X or Virgin Galactic offer a green route for commuting or tourism in low Earth orbit. Just beyond our atmosphere, space junk and space debris are multiplying at an exponential rate, jeopardising our communications and mapping satellites, and even putting our access to the wider solar system at risk. As more probes and landers head to the Moon and Mars, what plans are in place to deal with space debris far beyond Earth? Presented by Marnie Chesterton Produced by Jen Whyntie for the BBC World Service [Image: Space Junk. Credit: Getty Images]

This week CrowdScience investigates the information superhighway connecting mind with body. The Vagus nerve is part of our parasympathetic nervous system, delivering information from all our major organs to the brain stem, and stimulating it can help us switch off our fight or flight response and calm us down. But listener Mags wants to know what science says about its impact on our general wellbeing? Marnie Chesterton learns some deep breathing techniques and discovers how the length of our exhale is closely linked to our heart rate, all of which is important for developing something called vagal tone. Cold water immersion also said to stimulate the Vagus, so Marnie braves a freezing shower, only to discover she needs to get her face wet but keep the rest of her body dry, to avoid what scientists called autonomic conflict, which is when your stress response and calming response are both switched on by the same event. Activating both arms of the nervous system in this way can lead to serious heart problems in some people. New research into the gut-brain axis has shown that the Vagus nerve may be responsible for transporting the so-called happy hormone serotonin, which could have important implications for the treatment of depression. And innovations in electrical stimulation of this nerve means implanted devices may soon be used to treat inflammatory conditions like arthritis. Presented by Marnie Chesterton and produced by Marijke Peters for the BBC World Service Contributors: Dr Lucy Kaufmann, Adjunct Professor of Neurology, NYU Mike Tipton, Professor of Human and Applied Physiology, University of Porstmouth Mark Genovese, Emeritus Professor of Medicine, Stanford University Dr Karen-Anne McVey Neufeld, Brain Body Institute, McMaster University [Image credit: Getty Images)

The sudden agony of stubbing a toe or burning a finger can make even the most polite among us swear our heads off. It’s like a reflex, a quick-release valve for the shock. But why do expletives give us such a sense of relief? Why does it sometimes feel so good to swear? We set out to explore the science of swearing, prompted by a question from our listener Gadi. Psychological studies have shown bad language can relieve pain, or even make us stronger; we test out these theories for ourselves, and try to figure out why certain words are charged with such physical power. We don’t just use strong words in shock or anger, either. They can help us to bond with others, to express joy, solidarity, or creativity. And although people curse all over the world, it’s not quite the same everywhere. We hear what people like to swear about in different countries, and whether swearing in a second language can ever be quite so satisfying. Presented by Anand Jagatia Produced by Cathy Edwards for the BBC World Service (Photo: Woman swearing. Credit: Getty Images)

Listener Paula from Kenya is a computer scientist, she can’t help but notice the inequality in her workplace. With only 1 in 10 countries having female heads of state, there is no doubt that men are in charge. Paula wants to know if there is any scientific underpinning to this inequality? Perhaps it can be explained by our brains and bodies? Or does evolution weigh in? Or maybe it is all down to society and the way we raise our boys and girls. The toys and ideals we give our children must surely have an impact. And most importantly, if we want a world run by men and women equally, how can we get there? We hear how Iceland became the most gender equal country in the world. Presented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service [Image: Men in board room. Credit: Getty Images]

It’s the stuff of fairy tales – a beautiful cottage, with windows, chimney and floorboards … and supported by a living growing tree. CrowdScience listener Jack wants to know why living houses aren’t a common sight when they could contribute to leafier cities with cleaner air. The UK has an impressive collection of treehouses, but they remain in the realm of novelty, for good reasons. Architects are used to materials like concrete and steel changing over time, but a house built around a living tree needs another level of flexibility in its design. That doesn’t mean it’s impossible and CrowdScience hears about a project in the Ethiopian capital Addis Ababa, where architect Ahadu Abaineh made a three-storey, supported by 4 living Eucalyptus trees as a natural foundation. Host Marnie Chesterton meets some of the global treehouse building fraternity, including builder of over 200 structures, Takashi Kobayashi, who adapts his houses to the Japanese weather. In Oregon, USA, Michael Garnier has built an entire village of treehouses for his “Treesort”. He’s developed better ways of building , including the Tree Attachment Bolt, which holds the weight of the house while minimising damage to the tree. Professor Mitchell Joachim from Terreform One explains the wild potential of living architecture, a movement which looks at organic ways of building. He’s currently building a prototype living house, by shaping willow saplings onto a scaffold that will become a home, built of live trees. Photo Credit: Ahadu Abaineh

Do you find your bearings quickly or are you easily disorientated? Do your friends trust you with the directions in a new city? Finding our way in the physical world – whether that’s around a building or a city - is an important everyday capability, one that has been integral to human survival. This week CrowdScience listeners want to know whether some people are ‘naturally’ better at navigating, so presenter Marnie Chesterton sets her compass and journeys into the human brain. Accompanied by psychologists and neuroscientists Marnie learns how humans perceive their environment, recall routes and orientate themselves in unfamiliar spaces. We ask are some navigational strategies better than others? Marnie also hears that the country you live in might be a good predictor of your navigation skills and how growing up in the countryside may give you an wayfaring advantage. But is our navigational ability down to biology or experience, and can we improve it? With much of our modern map use being delegated to smartphones, Marnie explores what implications an over-reliance on GPS technology might have for our brain health. Presenter: Marnie Chesterton Producer: Melanie Brown (Photo:Lost man with map. Credit: Getty Images)

Could being happier help us fight infectious disease? As the world embarks on a mass vaccination programme to protect populations from Covid-19, Crowdscience asks whether our mood has any impact on our immune systems. In other words, could being happier help us fight infectious diseases? Marnie Chesterton explores how our mental wellbeing can impact our physical health and hears that stress and anxiety make it harder for our natural defence systems to kick in – a field known as psychoneuroimmunology. Professor Kavita Vedhara from the University of Nottingham explains flu jabs are less successful in patients with chronic stress. So scientists are coming up with non-pharmacological ways to improve vaccine efficiency. We investigate the idea that watching a short feel-good video before receiving the inoculation could lead to increased production of antibodies to a virus. And talk to Professor Richard Davidson who says mindfulness reduces stress and makes vaccines more effective. [Image: Happy couple wearing masks. Credit: Getty Images]

When planning to have a baby, women are expected to give up everything from smoking to alcohol, even soft cheese. But the other half of fertility comes from the sperm, usually provided by a man. So should men also give up their vices to improve the quality of their sperm, and their chances of conception? That’s what Listener Stuart in Australia wants to know. He emailed CrowdScience after he and his wife had been trying to have a second child for two years. He gave up alcohol, and coffee, but wants to know if there is any hard science to back up the idea that this would improve his fertility. To find out, presenter Anand Jagatia speaks with Professor Allan Pacey, a scientist who specialises in the study of male fertility and sperm. He discovers that male subfertility accounts for 50% the problems with getting pregnant. And we’re far from alone. Sperm is a remarkably diverse, but also fragile cell. Across the animal kingdom, different species have problems with male fertility, but have adapted novel ways to improve their chances of reaching the egg. Men often struggle to speak about their fertility, and reporter Chhavi Sachdev tells Anand the impact this has on couples in India who struggle to conceive, or don’t want to. She speaks with fertility specialist Professor Nirmal Kumar Lohiya about how this reticence to speak about fertility is changing. Viruses from Mumps to HIV have long been known to target the delicate sperm production cells in the testicles. Dr Krutika Kuppalli tells Anand why, and what we know about the possible impact of SARS CoV-2 on male fertility. Professor Allan Pacey gives Anand and Stuart some advice for what to do while trying to conceive - don’t wear tight underwear - and get used to talking about your swimmers or even getting them checked out. Contributors: Professor Allan Pacey - Andrologist at the University of Sheffield in the UK. Dr Nicolla Hemmings, expert on bird sperm, Royal Society Dorothy Hodgkin Research Fellow at the University of Sheffield, UK. Professor Nirmal Kumar Lohiya, Fertility specialist and co-developer of RISUG male contraceptive, University of Rajasthan, India Dr Krutika Kuppalli, Assistant Professor at the Medical University of South Carolina, USA Chhavi Sachdev, Reporter and presenter for CrowdScience Presented by Anand Jagatia, Produced by Rory Galloway (Image: Sperm cells Credit: Getty images)

Covid-19 has prompted a cleaning frenzy. CrowdScience listener William works as a personal trainer in a gym, and while cleaning’s always been part of his job, it’s now taken over much of his working day. He’s constantly wiping down equipment and doing regular deep cleans, and he reckons he can sanitize his hands 40 times in one shift. This kind of routine might strike a chord with many of us, and it’s certainly vital to take hygiene seriously during times of pandemic. But could there be any downsides to all this extra cleaning? There’s a whole world of microbes out there: some, like SARS-CoV-2, make us sick, but others are essential for our health. A rich microbiome is linked to a healthy immune system, while ‘good’ microbes help keep ‘bad’ ones at bay. And what about the chemicals in cleaning products – do they have any unintended consequences for our health? CrowdScience turns to the experts to ask whether our supercharged hygiene routines could damage our immune systems, or promote the spread of superbugs. And we hear why, as long as we have a good diet, plenty of fresh air, and ideally a furry pet, we don’t need to worry too much about being too clean. Presented by Marnie Chesterton Produced by Cathy Edwards for the BBC World Service (Photo credit: Getty Images)

When it comes to speed, humans have got nothing on cheetahs - or greyhounds, kangaroos or zebras for that matter. It’s over long distances we really come into our own: when running for hours or even days, our body structure and excellent sweating skills make us able to outpace much faster mammals. But what are the limits of human endurance? Can we run ever further and faster, and what’s the best diet to fuel such ambitions? This week’s questions come from two CrowdScience listeners in Japan who already know a fair bit about stamina, having run several marathons and long-distance triathlons between them. We head to Greece, legendary birthplace of the marathon, to witness an even more arduous challenge: hundreds of athletes following in the footsteps of the ancient Greek messenger Pheidippides, to run an astonishing 246km across the country. The ever-so-slightly less fit CrowdScience team do our best to keep up, and try to discover the secrets of these runners’ incredible endurance. Presenter: Marnie Chesterton Producer: Cathy Edwards (Photo: a runner in the Spartathlon ultramarathon, with kind permission from the International Spartathlon Association)

One of the more surprising consequences of the pandemic has been the trend for people wanting to move out of cities and back to the countryside. Not everyone has that privilege of course, but undoubtedly for some living in urban areas during lockdown, the lack of access to green spaces took its toll on their mental health and physical well-being. Now, with renewed hope of a global vaccine roll-out, ensuring more people have better access to nature is more important than ever, especially in cities of glass, steel and concrete. Italian CrowdScience listener Enrica loves nothing better than walking along the verdant riverbank near her home after a hard week at work. But is this activity doing more than making her feel good? Is it having an actual effect on her health? Presenter Anand Jagatia meets Enrica and visits a radical scheme in the city of Milan, where officials have been working hard to increase urban green features and have committed to planting 3 million trees and building twenty new parks by 2030. One such idea is the innovative Bosco Verticale - or vertical forest, planted up the side of two high rises apartment blocks. Amongst other benefits It’s hoped it could provide cooling microclimates to reduce the dangers of summer heat, and improve resident’s mental health. Produced by Jennifer Whyntie. First broadcast October 2019. (Photo: Tree lined "tunnel" in the English countryside of West Sussex. Credit: Getty Images)

As regular listeners may recall, CrowdScience has delved into the strange world of fungi before, as we dug down into the forest floor to reveal how plants and trees are connected to the vast mycelial network known as the “wood wide web”. But what makes this network possible and how might it have evolved? Fungi are incredibly clever, or at least , it appears that they’re capable of displaying complex behaviour that gives them the appearance of intelligence. In this episode, we speak to fungal ecologist and author of a new book, Merlin Sheldrake, about fungal “brains”, the evolution of magic mushrooms and zombie insects – the astonishing way certain fungi can take over the bodies of ants and wasps in order to sow their spores above ground. Presented by Anand Jagatia Produced by Rami Tzabar for the BBC World Service. Image: Getty Images

At Christmas, is there a better gift than knowledge? CrowdScience has cooked up its own version of 'secret Santa', with members of the team setting one another the challenge of answering surprising questions from all over the world. Are humans the only animals to exercise? Can you get colder than absolute zero? Why are sounds louder at night? When it comes to food dropped on the floor, is there such thing as the "three second rule"? And, does honey really have healing properties? Producers and presenters from the CrowdScience team speak to all manner of experts, from zoologists through to material scientists, to find the answers. Presenter: Marnie Chesterton Producer: Caroline Steel

CrowdScience listener Simon has a problem. He’s always bumping into things, dropping tools and knocking stuff over. And he’s sick of it. He wants to know what is going on. Was he born like this? Or is it contagious? And most importantly, can he do anything about it, or is he going to be the proverbial ‘bull in a china shop’ for the rest of his life? Host Anand Jagatia gets on the case, investigating the complex coordination needed for the simplest movements, like throwing a ball and catching it. With help from Dr Andrew Green, an exercise physiologist from Johannesburg University, he delves into our secret “sixth sense”, proprioception, which helps us locate our limbs without looking. Anand discovers that an easy task, like kicking a football, needs multiple parts of the brain to coordinate in order to work smoothly. Assistant Professor Jessica Bernard from Texas AMU studies the brain, particularly the cerebellum, a part that controls smooth movements. Dr Bernard explains how tiny glitches and larger lesions in different parts of the brain can make us clumsy in different ways. And how we use our thinking powers to stay balanced; a reason why, as your memory goes with old age, you’re more prone to falling over. Our listener is not alone. Around the world, there is an under- diagnosed condition that affects millions of us. Developmental Coordination Disorder (DCD), also known as dyspraxia is a motor coordination condition that affects 5% of the global population. As Professor Amanda Kirby from the University of South Wales and CEO of Do-It solutions explains, if you can’t tie shoelaces, catch a ball and your handwriting is awful, there’s a chance that you have DCD. There’s a large genetic component, so you are likely to come from a clumsy family. There’s no cure for DCD/Dyspraxia but all of us are capable of becoming better at a chosen task, and there’s a common pathway to mastery, whether that’s bike mechanics or open heart surgery. Professor Roger Kneebone is the author of Becoming Expert, and he talks to Simon about possible solutions to clumsiness, including accepting and living with it. [Image: Man slipping on banana. Credit: Getty Images]

The space between stars is usually measured in light years, but this makes it less easy to acknowledge the true scale of the distance. Even the closest star system to Earth, Proxima Centauri, is 4.2 light years or 40.13 trillion kilometres from Earth. If we are ever going to bridge the gap between the stars, we will have to have some very fast spaceships, with extremely reliable, long-lasting technology on board. So does science allow for these spacecraft to exist? That’s what listener Allan wants to know, and to find out, Presenter Anand Jagatia speaks with Tracy Drain, a systems engineer at NASA JPL responsible for overseeing the development and missions of multiple unmanned interplanetary probes including some around Jupiter and Mars. She tells us the challenges involved with simply keeping our spacecraft working for the long-haul. Even if we can overcome issues of wear and tear over time, powering a ship to other star systems will not be easy. Today’s chemical rockets are too inefficient for the job, so we speak with Rachel Moloney, a researcher in electric propulsion to ask if this relatively new technology could power ships through interstellar space. Faster than light travel is the solution most often found in Science Fiction, but it goes against Einstein’s laws of relativity. Is there a way around it? Theoretical physicist Professor Miguel Alcubierre thinks there may be, and he describes the way a spaceship may be able to create a bubble of spacetime around itself to move faster than light without breaking these fixed laws. But there’s a catch... Contributors: Tracy Drain – Systems Engineer - NASA Jet Propulsion Lab, California, USA Rachel Moloney – Researcher in Electrical Propulsion - Surrey Space Centre, UK Professor Samuel Tisherman – Surgeon – University of Maryland school of Medicine, USA Dr John Bradford – President & CTO of SpaceWorks, USA Professor Miguel Alcubierre – Theoretical physicist known for the ‘Alcubierre Warp Drive’ – National University of Mexico Presented by Anand Jagatia Produced by Rory Galloway [Image: Speceship. Credit: Getty Images]

From dumping raw sewage into rivers to littering the streets with our trash, humans don’t have a great track record when it comes to dealing with our waste. It’s something that CrowdScience listener and civil engineer Marc has noticed: he wonders if humans are particularly prone to messing up our surroundings, while other species are instinctively more hygienic and well-organised. Are we, by nature, really less clean and tidy than other animals? Farming and technology have allowed us to live more densely and generate more rubbish - maybe our cleaning instincts just aren’t up to the vast quantities of waste we spew out? CrowdScience digs into the past to see if early human rubbish heaps can turn up any answers. We follow a sewer down to the River Thames to hear about The Great Stink of Victorian London; turn to ants for housekeeping inspiration; and find out how to raise hygiene standards by tapping into our feelings of disgust and our desire to follow rules. Presented by Marnie Chesterton and produced by Cathy Edwards for the BBC World Service. [Image: Man on beach with rubbish. Credit: Getty Images]

This year, dramatic wildfires wreaked havoc across the globe from Australia to Siberia. CrowdScience listener Melissa wants to know the extent to which climate change is a factor in blazes that appear to be increasing in both frequency and intensity. Presenter Anand Jagatia hears how scientists use alternative worlds in computer models, to understand the role that global warming plays. After Siberia’s hottest ever year on record, he discovers the impact of increasing temperatures on boreal forests – and how they could help release huge stocks of carbon that has been stored in the soil. But is there anything we can do to prevent this happening? He visits the UK’s Peak District region, where conservationists are re-wilding a massive area with a special species of moss, which may offer a solution to an increase in infernos. Presented by Anand Jagatia and Produced by Melanie Brown for the BBC World Service. [Image: Forest Fire. Credit: Getty Images]

Every year, Western Afghanistan is hit with a fierce 120-day wind, and listener Hamid wants to know what causes this phenomenon? He’s from the city of Herat, where what starts as a gentle breeze in the morning can pick up to become a dangerous gale just a few hours later, devastating buildings and causing power outages. The BBC’s Abdullah Elham in Kabul tells us the country has plenty of other ‘friendly’ wind but this one is considered ‘fierce’. CrowdScience talks to Professor Amir Aghakouchak to discover more about the phenomenon, and learns about the pollution problems Herat’s summer storm causes in neighbouring Iran. But it’s not all bad news. Professor Lorraine Remer explains how NASA used satellites to map how wind transport Saharan sand almost half way round the world, fertilising the Amazon rainforest. Presented by Marnie Chesterton and produced by Marijke Peters for the BBC World Service [Photo: Tree in wind in desert. Credit: Getty Images]

We all feel pain on a regular basis; when we stub a toe, break a bone or even experience heartbreak. Bebeto from Cameroon wants to know how to cope with a pain in his wrist that just won’t go away. Does a positive mindset help? Or perhaps meditation? Marnie Chesterton speaks to psychologists and neuroscientists to find the answers. We hear from two people with very different experiences of pain. Lucy has fibromyalgia and experiences pain all over her body every day. While Stephen has a rare genetic condition which means he doesn’t feel physical pain at all. But they both argue that pain shouldn’t always be unwanted. Perhaps we need to embrace and accept our pain in order to beat it. Presented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service [Image: Man in pain. Credit: Getty Images]

CrowdScience listeners come in all shapes, sizes and ages. This episode is dedicated to our younger listeners who, as we’ve learned before, are experts at asking those superficially obvious questions that for parents, are anything but easy to answer. To start off with, Sylvia, asks why elephants are so big? As we hear from our expert – mammals were at one time, much larger – so perhaps the question should be, why aren’t they bigger? We investigate what drives body size in the animal kingdom. Presenter Marnie Chesterton, together with our ‘cub’ reporter Arlo, goes in search of the most brilliant scientific minds to respond to a slew of other queries. Shambhavi, from Singapore wonders why humans have five digits on each hand? And Benni from California asks why dogs don’t get sick when they drink from muddy puddles? Do dogs have some amazing ability to fight off viruses and bugs? Beyond the confines of our planet, we’ve also got a question from Olivia, from Sydney, Australia, who regularly contemplates the universe: what is the biggest object in it she wonders? Marnie and her experts do their best to solve these mysteries. Presented by Marnie Chesterton, produced by Dom Byrne for the BBC World Service. Image: Getty Images

We’ve probably all got a friend who sings along wildly out of tune - or maybe you are that person. But why are some of us apparently tone deaf, while others can hold a melody? Can you train yourself to sing in tune, or is it mostly down to raw talent? These musical questions, from CrowdScience listeners Jenny and Anastasia, certainly struck a chord with us. Anastasia loves to sing but her friends tell her she’s off-key - or that “a bear trod on her ear,” as they say in her native Russia. Is it possible for her to improve her singing voice, and what are the best ways of going about it? Both musicians and scientists help us tackle these questions, and explain what’s going on in our ears, brains and throats when we try to sing the right notes. We learn about congenital amusia, a condition which makes it almost impossible to tell if you’re in tune or not, and attempt to tease out the relative influence of our genes and our environment when it comes to musical ability. Presented by Marijke Peters and produced by Cathy Edwards for the BBC World Service. Image: Child Singing. Credit: Getty Images

All living things are related to each other, from elephants to algae, e-coli to humans like us. Within our cells we hold genetic information in the form of DNA or RNA. But despite viruses sharing these molecules, many scientists don't consider them to be 'life'. Viruses cannot reproduce on their own, but some can insert their DNA into a host to pass genes sideways through the branching tree of life. As a result, viruses’ relationship with life is.... complex. Two of our listeners had viruses on the mind, so they sent in the same question to CrowdScience. Senan from Singapore and Melvin from South Africa want to know how viruses began to see if this can tell us whether they shared a common ancestor with humans. To dig into this complexity Marnie Chesterton speaks with an expert on Koala genetics – Dr Rachael Tarlinton. Koalas are in the middle of tackling a retroviruses, a type of virus that plants DNA into our cells as a reproduction strategy. Her research could reveal why humans life has so much viral DNA within our genomes. Marnie speaks with a computational biologist Professor Gustavo Caetano-Anolles, who has found a new way to trace the family tree for billions of years using proteins common to all life on earth, and speaks with Professor Chantal Abergel who paints a picture of how viruses went from being the losers of evolution, to being highly successful parasites of cells. If you have a question for CrowdScience, please email: crowdscience@bbc.co.uk Produced by Rory Galloway Presented by Marnie Chesterton Contributors: Dr Chelsey Spriggs - Postdoctoral fellow at the University of Michigan in the USA Dr Rachael Tarlinton - Associate Professor at the University of Nottingham in the UK Professor Gustavo Caetano-Anolles - The University of Illinois in Urbana Champagne, USA Professor Chantal Abergel - Aix Marseille Université in France Graeme Dick - Head Keeper, Longleat Zoo and Safari Park, UK

Curious CrowdScience listeners have suddenly been struck by the oddity of their behaviours. Elise ponders why she blushes. Thankfully, listener David is a vascular surgeon and knows a thing or two about blushing, as he performs operations on people debilitated by constant red-dening. He has some answers for us, but asks why did blushing evolve? In the past, red cheeks have been linked to necrophilia, repressed cannibalism, and even a de-sire for men to experience menstruation! Thankfully, research has come a long way since then, as blushing experts Peter de Jong and Corine Dijk explain. Scientists believe that it evolved as a nonverbal signal to show someone you’re sorry or that you care about what they think. This would have important for our survival in the group, en-suring we didn’t get into a fight or get kicked out the group. Anand Jagatia gets to grips with blushing and other bodily behaviours – including a question from Thai listener Nitcha who wonders why we yawn as well as a question from Mohamed in Ghana and Biana in Trinidad and Tobago who both asked why people scratch their heads when they think. To answer these questions, Anand’s joined by yawning researcher Andrew Gallup and Sophie Scott as well as body language expert Blanca Cobb. Produced by Graihagh Jackson for the BBC World Service.

Crowdscience solves a range of listeners’ cosmic mysteries, from the reason we only ever see one side of the moon, to why planets spin, and discover the answer can be found in the formation of the solar system. We talk to astronomer Dr Carolin Crawford to understand how stars are made, and investigate the art of astronomy with journalist Jo Marchant, hearing how the ancient Greeks came up with a zodiac long before the invention of a telescope, revealing an intimate relationship between humans and the night sky. Presenter: Marnie Chesterton Producer: Marijke Peters [Image: The Solar System. Credit: Getty Images]

Why am I embarrassed to be naked? Chumbuzzo in Zambia wonders. And what would happen if we ditched our clothes and embraced nudity? Presenter Anand Jagatia and Producer Caroline Steel spend the day naked with other naturists to see if they can shift their embarrassment. Maybe there are good evolutionary reasons to cover up or perhaps we are contributing to inequality and negative body image by hiding our real selves? Marnie Chesterton explores different cultural attitudes to nudity and finds out about the science behind embarrassment. Clothes optional. Presented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service

Many of us willingly subject ourselves to pain and irritation by eating chilli. CrowdScience listener Tina wonders what’s driving this apparent masochism: why does ‘feeling the burn’ make so many of us feel so good? It’s just one of several tasty questions we tuck into in this episode. Also on the menu is stew: why does it taste better the next day? Listener Helen’s local delicacy is Welsh cawl, a meat and vegetable concoction. Tradition dictates it should be eaten the day after it’s made, but is there any science behind this? And we finish the meal with cheese. Listener Leander asks what makes some cheeses blue, some hard and crumbly, and some run all over your fridge. How is milk transformed into such radically different end products? Presented by Marnie Chesterton and Alex Lathbridge Produced by Cathy Edwards, Marnie Chesterton and Alex Lathbridge for the BBC World Service. [Photo:Woman eating red Chilli Pepper. Credit: Getty Images]

What does science say about controlling urination, and other bodily functions? We tackle three queries about peeing triggers, pooing positions and missing sweat. This episode CrowdScience presenter Marnie Chesterton poses some of the best listener follow-up questions that have landed in our inbox to a panel of experts. Listener Samuel in Ghana is wondering why watery sounds seem to induce urination. Producer Melanie Brown heads out to survey whether this is the case for individuals in an actual crowd at a public fountain in London. And urologist and trustee of the International Continence Society Marcus Drake talks Marnie through how he uses the sound of running water during his work as a hospital doctor helping patients with common but distressing peeing issues, and the limitations of research into this question. And he’s not the only listener who wants us to dig deeper into topics we’ve explored on the show before. Anna in Tokyo also got in touch after hearing our show about toilets, to ask if there is a toilet design that is most ‘natural’ for our health. Gastroenterologist Anton Emmanuel explains why small changes in people’s posture whilst pooing can have a significant impact on their quality of life. Finally, listeners Stelle, James and Joel emailed crowdscience@bbc.co.uk after hearing Marnie investigate hyperhidrosis: Sweating too much. They and their relatives experience the opposite:

If you’re one of the millions of people who used lockdown to try something new like baking sourdough bread, you may well be wondering what’s happening chemically inside your loaf, especially if the end result keeps changing. Well, you’re not alone. Listeners Soheil and Sean are both keen bakers but want to know more about the thing that makes bread rise: yeast. What is yeast? Where does it come from and can you catch it? And how hard is it to ‘make’ yourself? Soon after lockdown took effect, commercial supplies of the stuff disappeared from supermarket shelves across the globe. The shortage also affected brewers the world over. A big fan of yeast in most of its forms, Marnie Chesterton took on the challenge of creating her own. She talks to the brewers who hunt rare strains to create the perfect beer, and hears from the biologist who says these amazing microbes, used for thousands of years, could be used to make food production more sustainable. And she discovers how this simple ingredient could be instrumental in the fight against climate change. Presented by Marnie Chesterton and Produced by Marijke Peters for the BBC World Service.

Squelching into the science of slime, Chhavi Sachdev seeks to find out why it took so long for listener Helen Tyson to remove slime from her fingers, after she picked up a tiny slug while gardening. This unfortunate and hugely repulsive experience set Helen to wonder what it is about the structure of slug slime that makes it gloopy, so she sent Chhavi to meet with slug slime expert Professor Andrew Smith who reveals how the complex molecular structure of this pervasive fluid makes it so difficult to scrub off. Slime is used by all sorts of creatures including the Giant African Land snail, which invaded India by hitching a ride on imported timber. But invasive species biologist Dr TV Sajeev reveals that these snails are themselves giving a lift to another meningitis-causing parasite that can infect people. Chhavi looks for these massive molluscs in her own garden in Mumbai. Marine biologist Helen Scales describes how animals can use slime for catching food, mating, defence, or even transportation, and Chhavi speaks with Dr Adam Celiz who has been inspired by this slimy adaptability to create a tool that can provide new cells to replace damaged heart cells after a cardiac arrest. Slugs, snails and even fish keep a variety of useful chemicals in their slime. Some make them taste bitter, and others numb the mouth of predators, but they may also prevent the animals from contracting infections. Dr Sarah Pitt has investigated these compounds in the slimy mucus of a garden snail and discovered an antibiotic that is brand new to science. Slime is pretty disgusting, but it’s also completely fascinating. Presented by Chhavi Sachdev Produced by Rory Galloway (Photo: Slugs Mating. Credit: Getty Images)

Anyone else had their flight cancelled? The COVID 19 pandemic has had a huge impact on air travel – air traffic in 2020 is expected to be down 50 per cent on last year. But beyond the obvious disruption to business and people’s lives, how might the quieter skies affect our weather and climate? One curious listener, Jeroen Wijnands, who lives next to Schiphol airport in the Netherlands, noticed how there were fewer clouds and barely any rainfall since the flights dropped off. Could airplanes affect our local weather? Also, did we learn anything from another occasion when airplanes were grounded, during the post-9/11 shutdown? How will the current period impact our future climate? Marnie Chesterton investigates this question and discovers some of the surprising effects that grounded aircraft are having: on cloud formation, forecasting and climate change. Presenter: Marnie Chesterton, Producer: Dom Byrne [Photo:Commercial airplane parking at the airport. Credit: Getty Images]

Listener Avalon from Australia wants to know why people use conspiracy theories to explain shocking events. Are we more likely to believe conspiracy theories in times of adversity? What purpose do conspiracy theories serve in society? Marnie Chesterton speaks to the scientists to explain their popularity, even in the face of seemingly irrefutable evidence. Presented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service. Image: All-seeing eye of God inside triangle pyramid. Credit: paseven, Getty Images

These days we’re more acquainted with soap than ever before, as we lather up to help stop the spread of coronavirus. And for CrowdScience listener Sharon, this set off a steady stream of soapy questions: how does soap actually work? How was it discovered in the first place, long before anyone knew anything about germs? Are different things used for washing around the world, and are some soaps better than others? We set up a CrowdScience home laboratory to explore the soap making process with advice from science-based beauty blogger Dr Michelle Wong, and find out what it is about soap’s chemistry that gives it its germ-fighting superpowers. Soap has been around for at least 4000 years; we compare ancient soap making to modern methods, and hear about some of the soap alternatives used around the world, like the soap berries of India. And as for the question of whether some soaps are better than others? We discover why antibacterial soaps aren’t necessarily a good idea, and why putting a toy inside a bar of soap might be more important than tweaking its ingredients. Presented by Marnie Chesterton. Produced by Cathy Edwards for the BBC World Service. Image: Child with thoroughly washed hands. Credit: Getty Images.

Think of the oceans and an empty and peaceful expanse relatively untouched by humankind might come to mind. But is this peace an illusion? CrowdScience listener Dani wants to know if the noise of shipping and other human activity on the oceans is impacting on sea life. To find out, Marnie Chesterton takes a deep dive to learn how marine animals have evolved to use sound; from navigating their environments to finding a mate or hiding from prey. She then speaks to a scientist who is using acoustic observatories to track the many ways human activity - like sonar and shipping - can interfere. Marnie virtually visits a German lab which tests the ears of beached whales, dolphins and seals from around the world to try and ascertain whether they suffered hearing damage, and what might have caused it. What other smaller creatures are negatively impacted by underwater noise? Marnie learns that acoustic trauma is more widespread than first thought. As human life continues to expand along ocean waters, what is being done to reduce the impact of sound? Marnie meets some of the designers at the forefront of naval architecture to see how ship design, from propellers to air bubbles and even wind powered vessels can contribute to reducing the racket in the oceans. Presented by Marnie Chesterton. Produced by Melanie Brown for the BBC World Service. Main Image: The front of a humpback whale underneath the sea in Shetland Islands, Scotland, December 2016. Credit: Richard Shucksmith / Barcroft Im / Barcroft Media via Getty Images

Worms are not the cutest of creatures. They’re slimy, often associated with death and tend to bring on feelings of disgust in many of us. But listener Dinesh thinks they’re underrated and wants to know whether earthworms could be the key to our planet’s future agricultural success? He’s an organic farmer in India’s Tamil Nadu province who grows these annelids to add to the soil, and he wants Crowdscience to find out exactly what they’re doing. Anand Jagatia dons his gardening gloves and digs the dirt on these remarkable creatures, discovering how they can help improve soil quality, prevent fields from becoming waterlogged, and improve microbial numbers, all of which has the potential to increase crop yield. But he also investigates the so-called ‘earthworm dilemma’ and the idea that in some parts of the world, boreal forest worms are releasing carbon back into the atmosphere, which could have dangerous consequences for climate change. (Photo:

Shoes are a surprisingly recent human invention. But running isn’t. That means for most of our time on the planet, we’ve run barefoot. Today, in most countries it’s rare to see people out in public without shoes, let alone running. But might our aversion to the free foot be causing us pain? CrowdScience mega-fan Hnin is an experienced runner, she enjoys ultra-marathons back home in Australia. But about six months ago she developed extreme foot pain, the condition ‘Plantar Fasciitis’, and this has meant she had to stop doing what she loves. She reached out to CrowdScience presenter Chhavi Sachdev, to find out if barefoot running could reduce her pain and improve her performance. Simply put, is barefoot running better? In an attempt to find Hnin some answers, Chhavi hits the ground… running. Literally throwing off her own shoes on the streets of her home city of Mumbai, India, to see how feeling the ground can change her whole gait. And with Prof. Dan Lieberman, Chhavi learns what sets the human runner apart from other species while uncovering the strange form our feet have. She speaks with the Dr Peter Francis, a researcher whose life’s work has focused on curing the pain in his own feet and learning how to help others. But performance is also important for runners. Biomechanics and shoe expert Dr Sharon Dixon explains how modifications to the sports-shoe are helping marathon runners set records, and blade-running athlete Kiran Kanojia shows Chhavi how the technology behind her two prosthetic legs let her emulate either natural walking or natural running. Presented by Chhavi Sachdev Produced by Rory Galloway (Photo: barefoot running on beach. Credit: Getty Images)

If you put one person’s blood into another person , sometimes it’s fine and sometimes it’s a death sentence. French physician Jean-Baptiste Denis discovered this when he performed the first blood transfusion back in 1667. He put the blood of a lamb into a 15-year boy. The teenager survived but Denis’s third attempt killed the patient and led to a murder charge. In 1900, Austrian doctor Karl Landsteiner discovered the reason for this lottery – blood types. The red blood cells in our bodies are decorated with different marker molecules called antigens. These define us as A, B, AB or O blood type. And this is just one of 38 different systems for classifying our blood. CrowdScience listeners have discovered that we aren’t the only animal with blood types and want to know more. Dogs have 12 different blood groups, so how do they cope when they need a transfusion? CrowdScience meets some very good dogs who donate a pint to the pet blood bank in return for a toy and a treat. Each pint saving up to 4 other dogs’ lives. We also hear how examining our blood types can tell us more about our links to our ape-like cousins and how the human species spread around the world. And what about the future of blood types – can we use science, and animal blood to get around the problems of transfusions? Producer and Presenter: Marnie Chesterton Photo: Red Blood Cells. Credit: Getty Images

What exactly it means to be conscious has long been a question of profound debate amongst philosophers, and more recently, scientists. There are no easy answers, and it gets even trickier when you start asking whether animals are conscious: how can you find out about their subjective experience when they can’t tell you about it? Never afraid to tackle the impossible, CrowdScience is looking for answers after listener Natalie got in touch. She has lived with her cat for years and has a strong sense that he has thoughts and feelings: he has his own personality, acts in complex ways, and even has ‘grumpy days’. But is this consciousness? Is there any way of scientifically testing for it? How different from our own inner world is that of a cat, an octopus, or a bumblebee? And if we can find any answers to these puzzling questions, how does that affect the way we treat animals - not just our pets, but all the animals we share our planet with? We meet Natalie and her cat, and discover how scientists have explored the minds of pigs, cows and cuttlefish. Helping us ponder the elusive question of animal consciousness are philosopher Peter Godfrey-Smith, neuroscientist Anil Seth, animal welfare expert Donald Broom, ethicist Jessica Pierce, and comparative psychologist Alex Schnell. Featuring David Seddon as the voice of Chicco the Cat. Presented by Anand Jagatia and Produced by Cathy Edwards for BBC World Service. (Photo: Black Cat. Credit: Getty Images)

We were bowled over by a question from one CrowdScience listener in Australia wants to know how likely it is that the atoms in his body have been used in someone else’s body? We all like to think we are unique; no one is quite like us. But is that really true? Presenter Marnie Chesterton tackles Moshe’s question with help from every area of science. From geologists helping us work out how many atoms are on the Earth’s surface to biologists helping us work out how many atoms each body uses. Perhaps we are much less special than we think. Presented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service. (Photo:

Have you ever broken up a fight? Or pushed someone out the way of an oncoming vehicle, only to be hit by it yourself? Most of us probably haven’t taken as many risks as listener Alix, who has put herself in peril to save strangers on several occasions, and she wants Crowdscience to investigate why. At a time when medical professionals have to weigh up the personal dangers of working on the frontline of the Coronavirus crisis, it’s a particularly timely question. Marnie Chesterton finds out why it’s a good thing that children push the boundaries of what’s safe during playtime, because it makes them less anxious adults. And she questions the existence of the so-called bystander effect, discovering how evolution has ensured we’re a much braver species than we sometimes give ourselves credit for. But she hears from some social scientists who say there’s no such thing as a ‘hero’, however likely they are to intervene to help others. The virtual reality experience in this programme was created by the Human-Computer Interaction Lab of the University of Udine, Italy This programme has been updated since its original publication to correct an editorial error. Presented by Marnie Chesterton Produced by Marijke Peters

This week the kids take over. Our younger listeners are as curious as their parents, it seems, so presenter Marnie Chesterton seeks out the finest minds and attempts to answer a raft of their science questions, including why can’t you tickle yourself? Why don’t our eyebrows grow as long as the hair on our heads? Not content with humankind, these whizz kids have been pondering deeply about other animals. Ava, 9, from the UK wants to know if any other animals kill for fun, like some humans do. Not limited by planet Earth, these little thinkers have been contemplating even weightier questions. Joshua, 13, from Kenya wonders if our Solar System rotates around anything. And Seattle-based Michael, 10, puzzles over what would happen if a black hole collided with a wormhole. These and other mysteries are uncovered by Marnie and her experts. Presenters: Marnie Chesterton & Arlo Byrne Producer: Dom Byrne [Photo: Children Tickling each other, Adorable laughter. Credit: Getty Images]

There are over 7000 living languages on earth today. These mutually unintelligible means of communication are closely associated with different groups' identities. But how does a new language start out? That’s what listener BK wants to know. BK lives on one of the islands of the Philippines, where he speaks three languages fluently and has noticed there is a different language on almost every island. Presenter Anand Jagatia finds language experts from around the world who tell him about the many different ways that languages can form. Professor Dan Everett explains that languages naturally change over centuries to the point they are mutually unintelligible, and Quentin Everett describes how his research has identified striking similarities between biological, and linguistic evolution. Sally Thomason, Professor of linguistics in the USA tells us about the more unusual ways that languages can form through contact, or purposeful distancing measures, and Anand speaks with a producer of the BBC’s Pidgin service, about how the contact language nigerian pidgin may be developing into an official language West Africa. Finally, the inventor of a constructed language from the movie Avatar, tells CrowdScience what he has learned about language by creating the fully functional Na’vi language from scratch, and what Na’vi’s adoption by speakers around the world can tell us about the importance of language for creating community. Hearing from different languages from around the world through the programme, CrowdScience get to grips with the many ways new languages can form. Presented by Anand Jagatia, Produced by Rory Galloway (Photo: Chalk board of languages, Credit: Getty Images)

Despite being a universal need, talking about our toilet use and the infrastructure that aids us remains somewhat taboo. Whilst sectors like telecommunications and computing have undergone rapid transformations over the past century, the flush toilet and wastewater system have mostly remained unchanged. CrowdScience listeners Linda and Allison wonder if flush toilets – and the clean water used to wash waste away - make economic or environmental sense. So CrowdScience presenter Marnie Chesterton looks under the toilet lid, to probe (in a sanitary fashion) whether our sewerage systems and plumbed toilets are fit for purpose. In a future where population growth and climate change are likely to affect water demands, can we continue to use clean water to dispose of our waste and should the developing world be emulating this model? Around 2 billion people don’t have access to proper toilets or latrines, risking serious health consequences. Marnie investigates how countries without comprehensive sewerage infrastructure deal with human waste and how science is providing novel ways to dispose of - and use – human waste. Marnie speaks to a Kenyan scientist using poo-eating fly larvae to process faeces and a North American scientist who is developing a smart-toilet she hopes will monitor our health through sampling our daily movements. Are we ready to break taboos to innovate our toilet habits? Presenter: Marnie Chesterton Producer: Melanie Brown (Image: Man looking at toilet. Credit: Getty Images)

What is the smallest particle of matter? How does radiation affect our bodies? And, how is particle physics useful in our everyday lives? CrowdScience takes on particle physics questions from listeners all over the world. Marnie Chesterton and Anand Jagatia get help from particle physicists from the Large Hadron Collider at CERN and medical physicist Heather Williams. Presented by Marnie Chesterton and Anand Jagatia Produced by Cathy Edwards, Jen Whyntie and Louisa Field (Photo: Particle collider, Credit: Getty IMages)

What’s the importance of zero, and how was it discovered? How do scientists calculate Pi’s infinite digits? Why do so many people find maths difficult – and what’s the most difficult thing in maths? CrowdScience takes on a whole bunch of questions sent in by high school students in Spain. Like many children all over the world, their school is currently closed due to the coronavirus lockdown, but lessons continue at home. So how are their studies going, and can CrowdScience help out? We attempt to answer some of their trickiest maths questions, with the help of mathematicians Katie Steckles and Matt Parker, and mathematical biologist Kit Yates. Presenter: Marnie Chesterton. Producer: Cathy Edwards (Photo: A boy studying. Credit: Getty Images)

If you're an exercise fan, you'll know that sweating is how our bodies keep us cool, but how much water we lose and which bits of us get wettest depend on a whole host of factors. Jamaican listener Andre wants to know why he sweats in a heart-shape when he hits the gym, and we find out how everything from the clothes he wears to the moves he's doing explain his unusual perspiration patterns. In Kenya we meet a woman whose permanently clammy hands cause her to drop her mobile phone, and sweaty feet start to stink when she spends too long in shoes. Hyperhidrosis is a condition affecting millions of people worldwide but an expert explains some of the treatments for this mysterious condition. Presenter: Marnie Chesterton Producer: Marijke Peters Image Credit: Getty Images

If you have ever watched a spider as it works to build a web, spiralling inwards with a thread of silk, that intersects each glistening spoke with a precise touch of the foot, you will know that it is a remarkably complex behaviour. In this episode, presenter Geoff Marsh dives into the minds of spider-constructors as they build their webs. CrowdScience listener Daan asked us to find out how spiders can build webs without ever being taught how to do it. Are they just little robots controlled entirely by their genetic instructions? Spider silk expert Dr Beth Mortimer, describes the process of building a web in detail, while Professor Iain Couzin explains the simple modular behaviours that build up, in sequence, to create apparently complex instincts, like the huge locust swarms that are sweeping across vast areas of Africa and Arabia. Taking us deep under the exoskeletons of invertebrates, Professor Gene Robinson reveals an animal's behaviours can be altered by their genes, and the root similarity between learning and instincts. Spiders, despite their tiny size, have fascinating behaviours. Some jumping spiders can work out the best way out of a maze, and one arachnologist reveals how some social spiders can cooperate to build communal webs and capture moths that are many times their size. Geoff searches for the science that can reveal how instinct can create complex behaviour by setting up interviews at the homes of spider experts from around the world. Presented by Geoff Marsh. Produced by Rory Galloway for BBC World Service. Image: European garden spider, Araneus diadematus hanging in the web. Photo by: Michael Siluk / Universal Images Group via Getty Images

Listener Keith from Lincolnshire wants to know how to reduce stress as he is under extreme pressure as a firefighter. Not only does he have to cope with the stress of responding to emergency situations but he has to do it while wearing challenging breathing equipment. We all experience times of stress, especially given the current situation, our chest starts to feel tight and our breathing becomes shallow. Claudia Hammond – presenter of BBC World Service programme Health Check – explains steps we can take to protect our mental health during this pandemic. How should we alter our breathing to manage stress? Presenter Anand Jagatia speaks to breathing experts to find techniques to help listener Keith, and everyone else. Presented by Anand Jagatia. Produced by Caroline Steel for BBC World Service.

In medicine, it’s long been recognised that a placebo, a sham medicine or treatment, can have a powerful positive effect on a patient’s health. Part of that effect relies on a person’s belief that an inactive substance or treatment (for example, a sugar pill) is in fact an active drug. Placebos come in many forms, and the scientific study of placebo is an active area of research. With this in mind, CrowdScience listener Nigel got in touch to ask if can placebos be used to improve sports performance. As an amateur sports enthusiast, he’s been reading up on his sports psychology to try and improve his game, but he wonders if any coaches or psychologists use placebos to improve performance? Always ready to take up a challenge, presenter Anand Jagatia explores the world of endurance sport to find out how a placebo might used to improve athletes’ performances, as well as his own, and look at how advances in brain science are helping us understand the unusual neurobiology of placebo. And what of the amateur golfer, or rugby or table tennis player - can a placebo help? On an individual level, so called ‘verbal placebo’ is a technique that can help players with anxiety, confidence and concentration, and ultimately make them win more. And what about team sports? When, say, a new manager takes over at an ailing football club, and sparks a massive reversal in poor results, is that a placebo effect in action? The CrowdScience team investigates. Produced by Dom Byrne, presented by Anand Jagatia.

If you've ever felt the urge to shop till you drop, then you may already know about some of the clever ways retailers convince us to consume. From flash sales to so-called unbelievable offers, there are a whole range of techniques aimed at encouraging us to flash the cash. Listener Mo works in marketing, so knows more than most about the tricks of the trade - but he wants CrowdScience to investigate how neuroscience is being used to measure our behaviour and predict what we’ll buy. Marnie Chesterton finds out how brain scans are being used to discover which specific aspect of an advertisement a person is responding to, and then she hears how this information is being used by companies who want to sell us more stuff. But there's also evidence to suggest we have less control over these decisions than we think, and that computers are getting closer to detecting our intention before we're even aware of it ourselves. And this could have huge implications for the way we shop. Presented by: Marnie Chesterton Produced by: Marijke Peters (Photo:

Many of us are fascinated by our ancestry: knowing where our families came from can give us a sense of identity and roots. Tracing your family tree is a time-honoured tradition, but several companies now sell DNA tests that offer you insights into your heritage: so you might find out you’re 70% Nigerian, 39% Italian, or 11% South Asian, for example. There’s no doubt that genes contain clues about your family history, but how reliable are these commercial tests? That’s what CrowdScience listener Karen wondered after an update of her test results showed her going from 39% Scandinavian to 2% Norwegian. How confident can she be in her results now? And what does it actually mean to be 2% Norwegian, in terms of your family tree? Presenter Alex Lathbridge delves into his own African and European ancestry, talks to some of the companies offering these tests, and unpicks the complex relationship between genetic science and family trees. We meet a woman who found her long-lost uncle with a combination of a DNA test and old-fashioned archive research; and look to the Americas to ask whether genetic testing can restore ancestral ties erased by the inhumanity of the transatlantic slave trade. Presented by Alex Lathbridge Produced by Cathy Edwards for the BBC World Service (Photo: Elderly hands looking at old photos of self and family. Credit: Getty Images)

Since the outbreak of a new strain of coronavirus late last year, health workers and governments have been rushing to limit transmission by deploying containment tactics and anti-contamination campaigns. But, as the virus spreads around the world, what are scientists doing to help our bodies fight off or resist this new infectious disease? Viruses that cause human disease can be notoriously tricky to tackle. They don’t respond to antibiotics, can spread rapidly between human hosts, and even evolve improved ways of working as they multiply. Presenter Marnie Chesterton heads to the University of Oxford’s Nuffield Department of Medicine to meet the researchers who are urgently searching for solutions. Professor Tao Dong is Director of Chinese Academy of Medical Sciences Oxford Institute, collaborating with colleagues on the ground in China to see how Chinese patients’ immune systems are responding to the virus, which could inform vaccine design. Professor Sarah Gilbert leads the Jenner Institute’s influenza vaccine and emerging pathogens programme. She’s been developing a vaccine against another strain of coronavirus that caused the Middle East Respiratory Syndrome (MERS) outbreak, and is using the same technology to generate a new vaccine against the 2019 coronavirus. And, whilst that’s being developed, there is a possibility that some existing antiviral drugs may even help infected patients – Professor Peter Horby is working with colleagues in China on clinical trials to see what might work. CrowdScience goes into the laboratories using cutting edge science to combat coronavirus. Presented by Marnie Chesterton Produced by Jen Whyntie for the BBC World Service (Photo: Coronavirus Credit: Getty Images)

Jump on-board a doomed mission to the Moon. Apollo 13: the extraordinary story, told by the people who flew it and saved it. Search for 13 Minutes to the Moon wherever you get your podcasts. #13MinutestotheMoon

Why are we obsessed with crime? Kay from Hamburg, Germany asks as every Sunday evening Germans pile into their local pubs to watch Tatort, a hugely successful crime drama which has been running for 50 years. Presenter Marnie Chesterton starts with the science and speaks with psychologists to get to the bottom of where this obsession might come from. Have we evolved to have an innate obsession with danger or are we addicted to feeling fear? Or perhaps the dramatisation of crime fuels our obsession. Producer Caroline Steel visits the film set of BBC crime drama, Line of Duty. Producer Jed Mercurio explains what draws us to crime narratives and the techniques he uses to keep his audience captivated. But does the way we chose to represent crime in media match up with reality? And what is the impact of this on society and policy? (Photo: body outline. Credit: Getty Images)

Weather: wet, dry, cold, hot, sunny, windy or downright weird - there’s nothing quite like it as a conversation starter, from Austin to Jakarta. And judging from the large volume of emails about all things meteorological in the CrowdScience inbox, there’s plenty to talk about. What’s the weirdest weather on Earth, and how big a chance is there of it happening? Why does it always seem to rain on the days when we’re not working? And – conversely – is there any way we could make it rain when and where we need it to? Presenter Anand Jagatia finds out the answers to these questions and more by bringing together a panel of experts under the CrowdScience umbrella: Prof Liz Bentley, Royal Meteorological Society; Dr Anthony Rea, World Meteorological Organization, and Dr Rebecca Buccholz, National Centre for Atmospheric Research. Presented by Anand Jagatia. Produced by Jen Whyntie for the BBC World Service (Photo: Lenticular Cloud. Credit: Getty Images)

A lovely day out in the countryside can be blighted when swarms of midges or mosquitos invite themselves to the party. A CrowdScience listener in New Zealand has noticed that, when sand-flies come a-biting, she and her daughter are targeted, while her husband and other daughter escape unharmed. She wants to know why some, but not all of her family become bait for insect bites. CrowdScience delves into a world of smells, called semiochemistry, which explores the aromas one animal uses to attract or repel another. Does our attractiveness as a blood meal to insects come down to what we wear, what we’ve eaten or is it all in our genes? Host Marnie Chesterton discards the DEET and bravely offers herself up as a meal for mozzies, in a quest for answers. (Photo:Mosquito on skin. Credit: Getty Images)

Cancer is the second leading cause of death in the world. Many of us will at some point in our lives be confronted with the disease – either by falling ill ourselves or through a family member or friend. For CrowdScience presenter Marnie Chesterton, the diagnosis would change her life. The range of cancer symptoms and mortality rates vary considerably. Not all cancers are fatal and in some cases, cancer ends up more like a chronic debilitating disease, resulting in patients eventually dying from some other condition. This has got listener Gill in Scotland wondering – why do we call all cancers, cancer? And when did doctors first realise that all cancers are part of the same problem? First described by the Egyptians thousands of years ago and later coined by the Greek physician Hippocrates as “karninos”, the Greek word for “crab”, cancer is ominously absent from medical literature until the late 19th century. Throughout history it has puzzled, infuriated and enticed doctors and scientists to push medical science to its breaking point. Archaeologists have recently discovered that the ancient Egyptians had a term for cancer and that remedies they used then contain compounds that are found in modern chemotherapy. As we uncover the science and history of cancer, presenter Marnie Chesterton takes us on a journey through her own experience of living with and beyond the diagnosis and we examine the promise of future treatments. Presented by Marnie Chesterton. Produced by Louisa Field. [Photo: Cancer Cell. Credit: Getty Images]

Today, once-fatal diseases like the plague, sepsis, or cholera can be treated simply and quickly with a pill. These tiny tablets hold compounds that can fix illnesses, and most people don’t think twice about taking an asparin for a headache. Modern medicine looks nothing like the plants that many of them are derived from. But there must have been a moment, when the first humans decided that a particular plant, fungus, or mineral might cure them of an upset stomach, or infected wound. Right? That’s what listener Andrew Chen wondered, so he emailed CrowdScience to find answers. Presenter Anand Jagatia speaks with an archaeologist, a botanist, an ethno-pharmacologist, a zoologist and a historian to uncover the story of early human experimentation with ‘drugs’ from plants, fungi, animals and minerals. The history of humans is full of illness and poor health, and it seems we’ve always tried to fix this. Anand discovers the connection between food and medicine while making tonic water from scratch with Kim Walker at the Royal Botanic Gardens of Kew, and tastes the daisy-like Chinese herb that was first used thousands of years ago, and then – once tested - became one of the best modern drugs for treating the world’s most deadly infectious disease. Listener Andrew’s inspiration came from a previous episode of CrowdScience ‘Who were the first farmers?’ and so we return to expert anthropologist Cheryl Makerewicz who tells us about the ecological knowledge of hunter-gatherers and pastoralist communities. With Jaap de Roode, Anand discovers that conscious thought isn’t a pre-requisite of medical discovery, and historian Vivienne Lo explains how written word helped to standardise generations of medical knowledge in East Asia. Previously medical knowledge had been irrevocably linked with shamanism, magic and spirituality, but with modern medicine this changed – but today there is still much we can learn from ancient forms of knowledge, Christophe Wiart explains how his science focuses of discovering what plants tribal people in east Asia have used for centuries to cure their ailments. These early methods may help us combat new diseases today. Presented by Anand Jagatia Produced by Rory Galloway [Photo: Women using plant medicines. Credit: Getty Images]

CrowdScience heads to Freetown, Sierra Leone for a panel debate in front of a live audience to answer listener questions about how artificial intelligence is helping tackle some of the world’s most pressing issues. Anand Jagatia is joined by regional science experts to explore how robots, drones and big data are transforming sectors such as agriculture, health and governance. Could clever machines help eradicate invasive species? Will block chain IDs eventually replace physical documents? And while this technology is heralded as a force for change we’ll ask whether fears of an AI takeover are unfounded? Presented by Anand Jagatia and Produced by Marijke Peters and Mel Brown (Photo: The panel and Audience at Crowd Science live event in Sierra Leone. Credit: BBC)

Super-sized volcanic eruptions and giant asteroids crashing in from outer space are the stuff of disaster movies. They have listener Santosh from South Africa slightly concerned. He’d like to know what’s being done in real life to prepare for this kind of event. Although the chance of these events occurring is low, Santosh isn’t entirely wrong to be worried: Earth has a much longer history than humans do, and there’s evidence that several past extinction events millions of years ago wiped out the dominant species on the planet at the time, as we’ve heard before on CrowdScience. The kind of extraordinary geological and extra-terrestrial hazards thought to be responsible for the death of millions of lives do still exist. So is there really any way that humans could survive where the dinosaurs – and plenty of other species – have failed? Presenter Marnie Chesterton finds out by meeting experts who are already preparing for the remote but real possibility of the biggest disaster we could face. It turns out that in real life most things we can think of which could cause an extinction event are being watched closely by scientists and governmental agencies. How worried we should really be by the possibility of a sudden super-volcanic eruption at Yellowstone in the USA, or one of the other enormous volcanoes dotting our planet’s surface? Marnie heads into an underground bunker near the remote Scottish coast to find out if hiding out is a viable survival option. Now a museum, Scotland’s Secret Bunker, formerly RAF Troywood, is one of a network of nuclear shelters built by nation states during the Cold War. And she hears about one of the combined space agencies most ambitious projects yet: NASA and ESA’s Asteroid Impact and Deflection Assessment mission to crash an impactor into an asteroid’s moon to find out whether we could knock any potentially problematic collisions off-course well before Earth impact. Produced by Jennifer Whyntie for BBC World Service (Photo: Post apocalypse sole survivor. Credit: Getty Images)

Is there something bigger than infinity? Does quantum mechanics affect how I think? And why can I suddenly do algebra? As ever, we’re not afraid to tackle the big questions on CrowdScience. After a previous episode about the relationship between mathematics and reality, we received a flood of profound and difficult questions, so we dive back into the world of maths, physics and philosophy to try and answer them. A panel of experts help us puzzle out whether some infinities are bigger than others - and why that matters, as well as what quantum mechanics can teach us about the workings of the brain. And we seek answers for one of our listeners who surprised himself by being able to figure out mathematics equations he previously found unfathomable. With philosopher of physics Dr Eleanor Knox, mathematician Dr Katie Steckles, and Dr Aldo Faisal, an expert in neurotechnology. Presented by Marnie Chesterton Produced by Cathy Edwards for the BBC World Service Photo:

Reducing climate change and global warming is one of the biggest and most urgent challenges for everyone as we enter a new decade. The CrowdScience team have been trying to figure out how to play our part in reducing our carbon footprint. So what’s the best way forward? Presenter Marnie Chesterton starts to find out by pitting three of her colleagues against each other for the first phase of our challenge. Anand Jagatia, Geoff Marsh and Melanie Brown have all been tasked with answering a listener’s question in the lowest-carbon way possible. Along the way, they must monitor and account for every emission – from their travel methods to their choice of sustenance whilst working. It turns out that the challenge is not only in acknowledging all the types of activity that produce emissions, but in working out the volume of greenhouse gases produced. Marnie judges her colleagues’ efforts, determines a winner, and dispatches the losing challenger to look further into carbon calculation, and to find out about the possibilities of legitimately offsetting the overall footprint. And we start our on-going experiment using a broadcast industry carbon calculator to find out the most carbon-efficient and sustainable ways to keep answering everyone’s questions and sharing more cutting-edge global science. Presented by Marnie Chesterton Produced by Jen Whyntie for the BBC World Service (Photo:

Two years ago reporter Anand Jagatia travelled up beyond the Arctic Circle to meet Norwegian researchers in order to answer a question from US listener Kira on why some people function best in the mornings whilst others only come alive at night. In this episode we revisit the topic with the help of science writer and Parentland podcast presenter Linda Geddes, author of Chasing the Sun, a book which explores the science behind the sun’s effects on our bodies and our minds. The morning sun helps to kick-start our day and our body’s biological cycle – so what happens when it barely rises above the horizon or we live for prolonged periods in artificial environments where the sun never shines? Research has suggested that some communities in northern latitudes are better protected against the mental and physical effects of reduced exposure to sunlight in the winter which might have implications for those suffering the winter blues. Presenter Anand Jagatia, Producer: Rami Tzabar (Photo: Woman basking in the sun. Credit: Getty Images)

What is empathy? This week’s question comes from Maria in Amsterdam who has noticed that when one of her friends is in pain, she feels their pain too, literally. Maria wants to know - is she experiencing a type of ‘super’ empathy? To help find the answer, Marnie Chesterton visits the Netherlands Institute for Neuroscience and gets into an MRI scanner to discover what is happening in her brain when she empathises. She talks with a pro-social psychopath to find out how psychopaths experience empathy differently and how they navigate social situations. And Marnie meets with a mediator specialising in The Israeli–Palestinian conflict, to learn the value of empathy when the stakes are at their highest. (Photo: Back view of loving Mum hug teen daughter. Credit: Getty Images)

As CrowdScience celebrates its third birthday, the team takes time to revisit some of our early episodes, and catch up with listeners to discover if the answers we uncovered changed the course of their lives? We hear from Zach, who has learned to let go of a possibly lost memory and Erin, who discovered technology could hold the key to finding the man of her dreams. And two years after he emailed to ask why he couldn’t kick his habit, we ash Sharif whether he has finally managed to stop smoking? (Photo: Man listening to podcast. Credit: Getty Images)

Buzzing insects that sting and fall into your food can be annoying. But perhaps we should think twice before taking aim with the fly swatter because bug populations around the world are in rapid decline. This worries CrowdScience listener Daria; she wants to know what will happen to our food production without the help from our tiny friends – the pollinators? And what can she do, as a city-dweller, to help the bugs? The dollar value of agricultural services that insects supply – for free – is estimated to be 350 billion dollars worldwide. For scientists, a major challenge is the lack of long-term studies of insects on a global scale – in fact – entomologists worry that species are dying out faster than we can document their existence. The culprits, they believe, are climate change, invasive species, land-use and pesticides. CrowdScience speaks to the scientists who want to save the bugs; one project capitalises on the chemical signals that attract certain species of pollinators while others are building ‘bee hotels’ to encourage native bees back into our cities. Presenter: Marnie Chesterton Produced by Louisa Field for BBC World Service. (Photo: Hoverfly on Yellow Dandelion Flower. Credit: Getty Images)

66 million years ago, a huge asteroid hit the earth, wiping out most of the dinosaurs that roamed the land. It would still be tens of millions of years before the first humans appeared - but what if those dinosaurs hadn’t died out? Would we ever have evolved? CrowdScience listener Sunil was struck by this thought as he passed a Jurassic fossil site: if dinosaurs were still around, would I be here now? We dive back into the past to see how our distant mammal ancestors managed to live alongside huge, fierce dinosaurs; and why the disappearance of those dinosaurs was great news for mammals. They invaded the spaces left behind, biodiversity flourished, and that led – eventually – to humans evolving. It looks like our existence depends on that big dinosaur extinction. But we explore a big ‘what if?’: if the asteroid hadn’t hit, could our primate ancestors still have found a niche – somewhere, somehow - to evolve into humans? Or would evolution have taken a radically different path: would dinosaurs have developed human levels of intelligence? Is highly intelligent life inevitable, if you give it long enough to develop? We look to modern day birds - descendants of certain small dinosaurs who survived the asteroid strike - to glean some clues. With artist Memo Kosemen, palaeontologists Elsa Panciroli and Darren Naish, palaeobiologist Anjali Goswami, and Professor of Comparative Cognition Nicola Clayton Presented by Marnie Chesterton and Anand Jagatia Produced by Cathy Edwards for the BBC World Service (Photo: Silhouette of people and Dino. Credit: Getty Images)

Science fiction is full of people settling on distant planets. But even the closest stars would take millennia to reach with current speeds of travel, by the time any passengers reached an extra solar planet, they would be long dead. So CrowdScience listener Balaji asked us to find out whether humans could hibernate for interstellar travel? To uncover the science fact behind this idea, Anand Jagatia holds a tiny hibernating dormouse at the Wildwood Trust in Kent, and meets Dr Samuel Tisherman who puts his patients into suspended animation for a couple of hours, to save their lives after traumatic injuries that cause cardiac arrest. We ask if Dr Tisherman’s research could be extended to put healthy individuals to sleep for much longer periods of time? It’s a question that neuroscientist, Professor Kelly Drew is studying, in Alaska Fairbanks. She uses Ground Squirrels as a model to understand internal thermostats, and how hibernating mammals manage to reduce their core temperatures to -3 degrees Celsius. Anand speculates wildly with science fiction authors Adrian Tchaikovsky and Temi Oh whose characters in their books ‘Children of Time’ and ‘Do You Dream of Terra Two?’ traverse enormous distances between habitable planets. But is human stasis something that would actually be useful? John Bradford is the director of SpaceWorks, this company works with NASA to try to investigate human hibernation for space travel. He’s trying to make space-based human hibernation a reality, and it seems that may be closer than you’d think. Presented by Anand Jagatia Produced by Rory Galloway (Photo: People in hibernation. Credit: Getty Images)

Australian listener Lizzy is trying to reduce her footprint on this planet and is particularly interested in palm oil. It is everywhere - in shampoo, lipstick and face cream and even food stuffs like biscuits and spreads. In fact, WWF say it is used in 50% of all supermarket products so it's something most of us will come into contact with every day. Lizzy wants to know whether she should stop eating it. Because on the one hand, she sees emotive adverts depicting dying orangutans, deforestation and burning peatlands, releasing vast amounts of climate changing gases like carbon dioxide. On the other, she has read that palm oil is the most productive of the vegetable oils, using far less land than others. So would boycotting palm oil displace the problem elsewhere, she wonders? Would buying sustainable palm oil be best? Partnering up with with another BBC World Service programme, The Food Chain, presenter Graihagh Jackson heads to one of the biggest producers of palm oil: Malaysia. She visits small holder plantations, who collectively provide 40% of the world’s palm oil, to find out how palm oil is grown and to ask them about their perspective on a product that provides them with their livelihood. What would incentivise them to engage in greener practices? And what would that look like? For the latter question, Graihagh speaks to the largest sustainable certifier of palm oil, the RSPO and looks to science to see how we can continue to grow palm oil without having any more adverse effects on wildlife. This episode is part of the Crossing Divides season which runs from 18 - 24 November. You can find a link to the Food Chain episode below. Produced and presented by Graihagh Jackson with help from Marijke Peters and editor Rami Tzabar for the BBC World Service. (Photo: Woman shopping in supermarket Credit: Getty Images)

For decades science fiction has been imagining the incredible ways that machines might interact directly with our minds, from enabling telepathic communication to controlling robotic suits, solely using the power of thought. Getting computers to interface directly with the human brain has proven extremely challenging, but rapidly advancing computer technology is changing the landscape. CrowdScience listener Daniel wonders if we might finally be on the cusp of enabling machines to meld with our minds. To find out, presenter Alex Lathbridge goes in search of the latest efforts to connect brains to computers. He learns how researchers are combining brain scans with machine learning and gets to test whether an fMRI machine can decode his emotions. He then meets someone with a brain implant but discovers there are many hurdles to overcome before these become mainstream in clinical practice – for example, how can scientists develop implants that won’t damage the brain? With tech companies like Facebook and Elon Musk’s Neuralink starting to invest in this sector, many experts believe it is only a matter of time before thoughts are ‘readable’. Whilst currently this technology is focussed on helping people with serious medical conditions, other potential applications for it are raising ethical considerations. Could it be possible to read someone's mind against their will? Might this be used in warfare? Listener Daniel wonders how far this technology might go, leading Alex to ask an ethicist what mind-reading technology might do to society. Presented by Alex Lathbridge Produced by Melanie Brown (Photo: Telepathic people symbols are connected, mind reading as 3D illustration. Credit; Getty Images)

We’re all familiar with the sensation of sleepiness – heavy eye-lid, that warm, fuzzy feeling. But, one CrowdScience listener wants to know, what’s actually going on in our body and brain when tiredness takes over? Presenter Marnie Chesterton takes up the challenge and follows a trail that leads to circadian scientists working at the NASA Ames research centre in Silicon Valley. It turns out aviators and astronauts take sleepiness very seriously indeed. Marnie sends out roving reporter Anand Jagatia to investigate how our psycho-motor skills are affected by fatigue in a driving simulator. And we ask how does sleepiness change with age? Why, when tired, do adults crave a nap but children become ever more excitable? And what the hell’s going on with teenagers? We have some answers. Presented by Anand Jagatia Produced by Dom Byrne (Photo: Tired woman taking a nap at work sitting at office desk. Credit: Getty Images)

Most of us take the ability to speak fluently for granted, but for listener Breeda it has been a lifelong struggle. She has asked CrowdScience to investigate whether there is a cure for stuttering and, if not, what the best way to live with it is. Breeda is not alone, as stammering is a neurological condition that affects 70 million people worldwide. The CrowdScience team head to Oslo in Norway to follow a group of young people who have signed up for a highly disciplined and potentially life-changing training course. The first milestone is to learn to say their name without a stutter. For many, this is a huge challenge that triggers years of distress and anxiety. With hundreds of muscles and many parts of the brain being involved, speaking is one of the most complex tasks that humans perform. Scientists have discovered subtle differences in the insulation surrounding nerve cells, so-called myelin, between people who stutter and those who don’t. This irregularity may be the source of a tiny time delay in signals between crucial regions of the brain that need to work closely together to produce speech. In the future, it may be possible to stimulate certain brain areas to boost growth and connectivity. Presenter: Gareth Barlow Produced by Louisa Field for the BBC World Service (Image: Illustration of humans speaking with quotation marks, credit: Getty Images)

Crowdscience listeners Michael and Ricky have been walking a tributary of the River Thames in London, UK. They’ve noticed that there are loads of fish, which have only returned in recent years thanks to clean water initiatives. But what about salmon, they wonder? Could they one day return too? If they popped some salmon eggs in the river, would they return to spawn later on in their lives? Marnie Chesterton heads to Norway to find out whether it’s possible. There, she follows the life cycle of salmon, from birth to death and travels to the salmon’s spawning grounds, before following their path out to sea and beyond. She explores the science behind ‘natal homing’ - returning to the place of your birth in order to reproduce. It isn’t just confined to salmon. But how does it work? Marnie also learns to fish as she joins an active research project that's evaluating if escaped farmed salmon are threatening their wild counterparts by interbreeding. Could this stop salmon swimming home? Back in the UK, Marnie finds out if all this Norwegian expertise could be transplanted to a river in London? Quite possibly, but it's not without its challenges, as the UK's Environmental Agency found out after attempting to re-introduce salmon into the River Thames. Presenter: Marnie Chesterton Produced by Graihagh Jackson for the BBC World Service (Photo: The mighty Wild Atlantic salmon travelling to spawning grounds in the Scottish highlands. Credit: Getty Images)

Faced with one cake and eight hungry people, it’s pretty obvious how maths underpins reality. But as mathematics gets further from common sense and into seemingly abstract territory, nature still seems to obey its rules - whether in the orbit of a planet, the number of petals on a flower, or the structure of an atom. But what exactly is the relationship between mathematics and reality? That’s the impossibly difficult question CrowdScience has been set this week by our listener Sergio in Peru. It’s one that’s been pondered by humans for millennia: the Greek philosopher Pythagoras believed “All is number”. Is maths a human construct to help us make sense of reality - a tool, a model, a language? Does maths create its own reality? Or is it reality itself? CrowdScience explores these questions with the help of experts from the fields of philosophy, mathematics and science: Dr Eleanor Knox, Dr Eugenia Cheng, Professor Lucie Green, Alex Bellos and Stefano Centineo. Presenter: Marnie Chesterton Produced by Cathy Edwards for the BBC World Service (Photo: A young woman with her eyes closed standing in front of chalkboard, working out maths formulas. Credit: Getty Images)

Human life expectancy has been increasing for decades. In many developed countries, we can now expect to live into our 80s, and it isn’t uncommon to live to 90 or even 100 years old. But eventually our bodies fail, old age is undoubtedly a clear indicator of approaching death. This fact annoyed 79 year old CrowdScience listener Bill, who emailed in to set presenter Geoff Marsh the task of seeking out the secrets to a longer, healthier life. Bill has a personal target to live to 200 years old, so can he do it? Well some people appear to age more slowly. In one part of Costa Rica, people commonly hit their hundredth birthday. CrowdScience’s Rafael Rojas visits these Central American centenarians to ask them their secrets to a longer life. Then, in interviews with the best age researchers around the world, including Professor Linda Partridge and Professor Janet Lord, Geoff reveals the science behind longer lifespans, and what people can do to live for longer, healthily. Presented by Geoff Marsh Produced by Rory Galloway (Image: A group of older men sitting together at an event, Costa Rica. Credit: Rafael Rojas)

The number of vegans is on the rise in many parts of the world, with many people swearing by the health benefits of a plant-based lifestyle. But is a vegan diet really better for your health? Is there any evidence to show that vegans are likely to live longer? And what about the new, highly processed meat analogues becoming increasingly available in supermarkets and restaurants menus? They look, feel and taste just like meat products but what affect are they having on our health? To find out more, presenter Anand Jagatia talks to the experts and joins listener Samantha in following a vegan diet. Presenter Anand Jagatia Produced by Caroline Steel for the BBC World Service (Photo: Healthy vegan food with herbs and spices. Credit: Getty Images)

Sir Arthur Conan Doyle’s famous fictional detective is renowned for his feats of memory, his observational capacity, tireless energy and an almost supernatural ability to solve the most perplexing crimes from seemingly unconnected facts. CrowdScience listener Asghar wants to know whether the way Sherlock Holmes solves crimes goes beyond fiction. What does science have to say about the matter? We pit fact against fiction with a leading forensic expert, a sleep scientist and presenter Marnie Chesterton puts herself to the test under the guidance of memory champion Simon Reinhard. She discovers that most humans are able to train their brain to rival the memory capacity of Sherlock Holmes. And who wouldn’t want that? Presenter: Marnie Chesterton Producer: Louisa Field (Photo: A Sherlock Holmes hat and magnifying glass on a wooden table. Credit: Getty Images)

The World Health Organization ranks migraines as the second most disabling neurological disorder in the world and in people under the age of 50, it is the single most disabling medical condition. With stats like that, it’s no wonder that so many CrowdScience listeners have got in touch wanting help with their headaches. Peter from Germany askes what happens in his brain when he’s got a migraine, whilst Nika from Germany has found that changing lifestyle has dramatically reduced hers but she’s not sure why. What’s the link between diet, exercise and migraines, Nika wonders? Meanwhile, Judy from USA wants to know if there’s a cure, as her son gets chronic migraines and she wants to know what the future looks like for him. Anand Jagatia and migraine sufferer Graihagh Jackson take a trip into the neurology of migraines, investigating some of the latest research in headache and migraine research to find some answers. Presenters: Anand Jagatia & Graihagh Jackson Producer: Graihagh Jackson (Photo: A young man suffering from a migraine. Credit: Getty Images)

Sociable, lively, outgoing people are highly valued in certain cultures - think of the stereotype of the hyper-confident American. And there’s even evidence that extroverts all over the world tend to be happier. But are the positive qualities that quieter types can bring to society being ignored or underappreciated? And couldn’t introverts be just as happy as extroverts, if only they lived in a more accepting culture? These are controversial areas of personality psychology into which CrowdScience strayed earlier this year when exploring the question “Why am I shy?” It prompted a whole bunch of other questions from our listeners which we tackle in this follow-up programme, with the help of psychologist and shyness expert Professor Jonathan Cheek. We probe the links between happiness, personality and culture, and find out what makes introverts happy. Presenter: Datshiane Navanayagam Producer: Cathy Edwards (Photo: A woman smiling with her arms spread out. Credit: Getty Images)

Satellites have transformed our lives, giving us digital communications, navigation and observations of Earth, and even an artificial place to live above the atmosphere: The International Space Station. CrowdScience listener Dana wants to know: would more of these satellites and stations help us get back to the Moon, as well as further into the solar system? As we discovered in a previous episode, being able to mine resources such as fuel and water in space could be handy for extra-terrestrial exploration. Asteroids could perhaps one day become self-fuelling gas stations for spaceships, as many contain ice which you could turn rocket fuel (hydrogen and oxygen). But what else would astronauts need for living beyond Earth? Marnie Chesterton asks the engineers working on the possibilities – from communications satellites that could transform lunar missions to a brand new moon-orbiting space station: The Lunar Gateway. These technologies could help humans get back to the Moon, and perhaps one day to Mars, for hopefully reduced costs – but funding missions beyond our planet still isn’t going to be cheap. Why might we need deep space-based infrastructure, and how could it help humanity back here on Earth? Presented by Marnie Chesterton Produced by Jennifer Whyntie for the BBC World Service (Photo: International Space Station, orbiting Earth. Credit: The Science Photo Library)

Many of us struggle to motivate ourselves to carry out certain tasks, from hanging out the washing to writing a job application. How can we best motivate ourselves? And how can we avoid procrastination? Listener Moses in Uganda wants to find out. Presenter Anand Jagatia puts the science to the test as he trains and participates in an open water swimming race which Marnie Chesterton has kindly volunteered him for. Presented by Anand Jagatia and Marnie Chesterton Produced by Caroline Steel for the BBC World Service (Photo: Yes you can, motivational message written on a sandy beach. Credit: Getty Images)

CrowdScience listeners Mark and Jess have been watching TV series, The Handmaid’s Tale. It's an adaptation of a book by Margaret Atwood and depicts a dystopian future where many have become infertile. The remaining few fertile women, known as Handmaids, are forced into child-bearing servitude. Why so many have become infertile isn’t clear but the series hints at several possible causes, from radiation to environmental pollutants. All of which got Mark and Jess wondering… What could cause mass infertility? Would we descend into a political landscape akin to Gilead? Award-winning author Margaret Atwood has left a paper trail for us to follow in the pages of her novel. There’s a ream of possible causes, and so Marnie Chesterton investigates which ring true. Presented by Marnie Chesterton. Produced by Graihagh Jackson for the BBC World Service. (Photo: Filming of the Handmaid's Tale. Credit: Getty Images)

Humans have been trying to predict the future since ancient times. The Chinese had the I-Ching while the Greeks preferred to search for answers in animal entrails. These days intelligence agencies around the world mostly rely on expert opinions to forecast events. But there are ordinary people among us that routinely outperform experts when it comes to making accurate predictions about the future. Listener Cicely wants to know whether these non-experts, so-called “super-forecasters”, really exist and if so, how does it work? She has noticed that people in her family – herself included – are surprisingly good at predicting events. CrowdScience investigates and finds that there is no hocus-pocus involved. On the contrary, scientists have found that super-forecasters tend to have certain personality traits and skills. And there is more good news; researchers believe that these skills can been taught. CrowdScience presenter Graihagh Jackson takes up the challenge and tests her own predicting abilities. Presented by Graihagh Jackson and produced by Louisa Field (Photo: A barefoot woman on a beach, showing two lucky dices in her hands. Credit: Getty Images)

The odds of becoming a fossil are vanishingly small. And yet there seem to be an awful lot of them out there. In some parts of the world you can barely look at a rock without finding a fossil, and museum archives worldwide are stuffed with everything from ammonites to Archaeopteryx. But how many does that leave to be discovered by future fossil hunters? What’s the total number of fossils left to find? That’s what listener Anders Hegvik from Norway wants to know and what CrowdScience is off to investigate. Despite not having the technology or time to scan the entire planet, presenter Marnie Chesterton prepares to find a decent answer. During her quest, she meets the scientists who dig up fossils all over the world; does some very large sums; and asks, have we already found all the T-rexes out there? Presented by Marnie Chesterton and produced by Anna Lacey (Photo: Fossilized dinosaur bones and skull in the send. Credit: Getty Images)

Do you stick your tongue out or scowl when you concentrate? Maybe, like one of our listeners, you screw up your face when you’re playing music. Do these facial expressions actually help with the task in hand? And could they hold clues to humans’ evolutionary past? In this edition of CrowdScience we tackle the science of face-pulling, along with several more burning science questions sent in from listeners around the world. We explore why it’s almost impossible to talk without moving your hands; and why bilingual people often switch to the first language they learned when they’re counting, even if they speak another language the rest of the time. Presented by Anand Jagatia and Marnie Chesterton Produced by Cathy Edwards (Photo: A boy sits at a table, looking down in concentration as he draws in a note pad. Credit: Getty Images)

Laser swords, time machines, matter transporters - before the turn of the millennium, movies, books and television promised some extraordinary future technology. Now we’re twenty years into the next century and CrowdScience listeners are wondering: Where is it all? Marnie Chesterton delves into the sci-fi cupboard to dust off some imaginary gadgets and find out if any are finally becoming reality. How far into the future will we have to go to find a time machine as imagined by H.G. Wells in 1895? Where are the lightsabers wielded by fictional Jedi? Why are we still using cars, planes and trains when a matter transporter or a flying taxi could be so much more convenient? Marnie is joined by a panel of experts to find out if and when any of these much-longed for items are going to arrive. Presenter Marnie Chesterton. Producer Jennifer Whyntie (Photo: Dr Who, Tardis. Travelling through time and space. Credit: BBC Copyright)

Farming is a relatively recent invention for our species. For most of human history, people were hunter-gatherers. They moved around the landscape to get their food, hunting prey and gathering fruits and cereals from their environment. But then, around 10 thousand years ago, human society shifted, and the first farmers appear in archaeological records around the world. So how did this idea start? Who planted the first seed and domesticated the wild ancestors of our cows and chickens? That’s what Listener Brian wanted to know, and so CrowdScience presenter Anand Jagatia seeks out the archaeologists, geneticists and anthropologists who can give us the answers. Presenter: Anand Jagatia, Producer: Rory Galloway (Photo: A farmer working in a green cotton field with two bulls. Credit: Getty Images)

For some people, the idea of eating soil is weird at best and at worst disgusting and dirty. But globally the practice of geophagy – or the regular and intentional consumption of earth – is more common than you might imagine. The ancient Greek physician Hippocrates described it 2500 years ago and even today, eating soil, earth and clay can be seen in a wide range of human cultures as well in hundreds of animal species. But what’s the point of it? And what’s going on in the body to drive cravings for things that aren’t bona fide food? That’s the question bothering CrowdScience listener Amy. Anna Lacey discovers the special properties of the soil people eat and the purpose geophagy might serve for our health. She also finds out the extent to which our bodies can tell us what we’re lacking and drive us to crave the substances we need to reset the balance. Produced and Presented by Anna Lacey (Photo: Hands holding some soil. Credit: Getty Images)

It’s frustrating to be stuck in traffic. Listener Collins from Nairobi, Kenya, spends at least three hours a day in traffic and he counts himself lucky. Many of his friends will easily spend six hours in traffic jams to get back and forth from work. Collins wants to know whether there is hope for his hometown – has any city managed to eliminate the worst of the traffic hot spots and how did they do it? Collins is not alone in his frustration. CrowdScience finds that congestion plays a major factor in the happiness and health of urban citizens. Commuters have been measured to have stress levels equivalent to that of riot police facing angry protesters. So should our cities cater less for cars and what are the alternatives? Presenter Gareth Barlow heads to Copenhagen to meet the politicians and urban designers who have transformed the Danish capital from a city for cars to one for bikes and people. Presenter: Gareth Barlow. Produced by Louisa Field (Photo: Afternoon traffic along Likoni road in Nairobi's Kilimani susburb. Credit: Getty Images)

Breathing is automatic: awake or asleep, running or resting, our bodies unconsciously make sure we get enough oxygen to function. But - unlike other bodily functions such as heart rate and digestion - it’s not hard to control our breathing consciously. If you’ve ever been to an exercise, meditation or yoga class, you’re probably familiar with instructions about how and when to breathe. It was one of these instructions - “breathe in through your nose and out through your mouth” - that prompted CrowdScience listener Judi to wonder if this really was the best way to breathe during her exercise class. Is there good evidence to support the benefits of different breathing techniques - whether through the nose or mouth, fast or slow, noisy or quiet? And is consciously controlling your breath more about improving psychological focus, or optimising body mechanics? Sports scientist Mitch Lomax takes us through the biology, chemistry and physics of breathing, and shows us how to train our respiratory muscles. We meet yoga guru Hansa Yogendra in India, where the study of pranayama - literally “breath control” in Sanskrit - is thousands of years old; and find out what scientists have discovered about the effects of these ancient techniques on the body and mind. Presenter: Anand Jagatia. Producer: Cathy Edwards (Photo: A woman jogging outside, wearing sports clothes on a blue sky background. Credit: Getty Images)

For decades, people suffering from chronic depression have relied on medicines that affect the levels of chemicals in the brain like serotonin, which regulate mood and emotion. But ten percent of people don’t benefit from any of the existing treatments for this devastating condition. Sisters Annie and Kathryn have both been diagnosed with long-term depression that makes it hard for them to experience pleasure as others do. But they’re interested in whether there are new solutions on the horizon that could improve their wellbeing, in particular ones that don’t necessarily involve conventional medication. Datshiane Navanayagam learns how a technique called mindfulness could strengthen neural connections in bits of the brain that communicate with each other. This, it’s said, may harness the ability of the brain to adapt and self-repair which can change people’s emotional responses to life’s ups and downs. She meets a psychologist who shows how this simple technique could improve our overall ability to process information and reverse negative thought patterns. CrowdScience also hears about cutting edge research into the use of psychedelics as potential treatment for depression and heads to the UK’s only centre for ketamine therapy, where patients say a drug once popular with partygoers, is having a profound effect on their mental health. Produced by Marijke Peters for BBC World Service. (Photo: A woman sitting on the top of a mountain and meditating. Credit: Getty Images)

Singing can lift our spirits, but research suggests it could also benefit our health, improving breathing for people with lung conditions and helping us cope with dementia. Could it even have a preventative effect? CrowdScience heads to Cheltenham Science Festival in the UK county of Gloucestershire - one of the first places to pioneer this kind of “social prescribing” - to find out. Presenter Anand Jagatia teams up with panellists Dr Daisy Fancourt, Senior Research Associate in Behavioural Science, Dr Simon Opher, family doctor and Clinical Lead for Social Prescribing, and Maggie Grady, Director of Music Therapy at charity Mindsong to learn more. They’re joined on-stage by their Breathe In Sing Out and Meaningful Music volunteer singing groups to find out what this much-loved musical pastime can do for us. Producer: Jen Whyntie (Photo: Students singing in a choir with their teacher. Credit: Getty Images)

Medical intervention has disrupted natural selection in humans as many more children survive into adulthood than did a few centuries ago. And as our DNA continues to evolve, in order to adapt to our environment, how might human beings of the future be different from us? Anand Jagatia explores how some humans, over just a few thousand years, have adapted genetically to live at high altitudes of the Tibetan Himalayas or in the cold climates of Inuit Greenland. Several Crowdscience listeners got in touch to ask about the ways in which humans might evolve in future but understanding how we’re adapting to modern ways of living is much harder to measure. So what adaptions do evolutionary biologists expect for the human race? How will IVF, gene-editing, mass migration and our constantly changing culture affect how we evolve? Presenter: Anand Jagatia. Produced by Dom Byrne and Melanie Brown for BBC World Service (Photo: People in a crowded street. Credit: Getty Images)

As scientists keep finding ever more fascinating facts about the invisible housemates that share our homes, we dust off our episode on what might be lurking in quiet household corners or under our beds. Marnie Chesterton reminds us how dust can contain all sorts of secrets about our habits and everyday lives, and Anand Jagatia bravely ventures into parts of our homes that are usually overlooked. He heads out on a microbial safari with expert tour guide Dr Jamie Lorimer from the University of Oxford to find out what kind of creatures are living in our kitchens, bathrooms and gardens - from bacteria normally found in undersea vents popping up in a kettle, to microbes quietly producing tiny nuggets of gold. For so long this hidden world has been one that we’ve routinely exterminated - but should we be exploring it too? Presenters: Marnie Chesterton and Anand Jagatia. Produced by Jen Whyntie for BBC World Service. (Photo: A woman using a damp sponge to clean dust collected on a window sill. Credit: Getty Images)

Where the conditions are right, life can arise. But what might the ‘right’ conditions be? Could the dark sector of our Universe be inhabited? That’s what Gautam from Delhi, India has been wondering. He points out that dark matter and dark energy make up around 95% of the Universe and the remaining segment is normal matter - the stuff we’re all made up of. Given that there’s so much of this dark material, could dark life have evolved? Marnie Chesterton investigates with Dr Matt Middleton, Dr Burçin Mutlu-Pakdil and Dr Renato Costa. Together, they unpick what dark matter and dark energy are and test out some listener theories as to what these mysterious mediums might be. For instance, Yoseph from Ogden, USA questions whether black holes could account for the missing matter and it turns out, he might just be on to something… Presented by Marnie Chesterton. Produced by Graihagh Jackson for BBC World Service. (Photo: Arrangement of Nebula, Stars and a colourful galaxy. Credit: Getty Images)

Our bodies are made of cells, tens of trillions of cells. They all have particular roles and functions in the body, from digesting food, to producing hair, to hunting down pathogens. But all of this incredible complexity started as just a single cell. Gila, from Israel, asked CrowdScience to find out how the development of incredible structures, and systems in the body are coordinated by the cells. Are cells communicating? How do cells know what they should be doing? To find out, Geoff Marsh meets a Cambridge researcher uncovering the first cell division in our lives, and peers into a fertile chicken egg to see the developing embryo as it grows a limb. CrowdScience finds out why scientists like Dr Megan Davey use chickens to understand the development of human fingers and investigates how individual cells with the same DNA manage to choreograph a dance of cell replication, movement and communication to create our bodies in all of their complexity. Presenter: Geoff Marsh Producer: Rory Galloway (Photo: Cells grouped together. Credit: Getty Images)

Many of us enjoy cooking – but when did we switch from eating our food raw, to heating it? Listener Logan enjoys his beef burgers rare, but wants to know why he still feels compelled to grill them? Presenter Anand Jagatia travels to a remote South African cave where our ancestors first used fire at least a million years ago, which one man says could help prove when our species started cooking. And he talks to a scientist who shows how the composition of food changes when it’s cooked, to allow us more access to give us more access to calories - and hears how a completely raw food diet could have disastrous consequences for health. Producer: Marijke Peters Presenter Anand Jagatia (Image: A large pan held over an open fire. Credit: Getty Images)

We are slowly running out of ammunition to fight antibiotic resistant bacteria. Listener Peter wants to know whether a therapy that he’d heard about in the 1980s could be revived to help us where antibiotics falls short. CrowdScience travels to Georgia where “phages”, viruses that hunt and kill bacteria, have been used for nearly 100 years to treat illnesses ranging from a sore throat to cholera. Phages are fussy eaters – a specific phage will happily chew on one bug but ignore another. In Georgia, scientists have kept rare phages safe for decades and are constantly on the look-out for new ones. CrowdScience presenter Marnie Chesterton speaks to the scientists and doctors who are pioneering phage-therapy as well as overseas patients who have travelled thousands of miles in hope of finding a cure. Presenter: Marnie Chesterton Producer: Louisa Field (Photo: Bacteriophage infecting bacterium. Credit: Getty Images)

We are all made of particles – but what are particles made of? It’s a question that’s been perplexing scientists for centuries - for so long, in fact, that listener Doug in Canada wants to know if there’s a limit to how much they can ever discover. CrowdScience heads out to CERN, in Switzerland, to find out. Birthplace of the internet, home to the Large Hadron Collider, and the site of the Higgs Boson’s discovery – the fundamental particle that is thought to give all other particles their mass, and one of the most important scientific finds of the 21st Century. But that revelation wasn’t an end to the quest – in fact, it has raised many more questions for the physicists and engineers involved. Dr David Barney, CMS, and Dr Tara Nanut, LHCb, tell us why. And now they have announced that they are considering building a new, larger particle collider to find answers. The Future Circular Collider would be a hundred kilometres long and sited partly under Lake Geneva, smashing together sub-atomic particles at unprecedented energies in the hope of revealing the fundamental building blocks of all matter in the Universe. But any outcomes are by no means certain, and it could cost up to €29 billion. Perhaps physicists need to think completely differently about how to unpick what makes our universe – we see how one research team at Rutherford Appleton Laboratory near Oxford is doing just that, as they’re developing a collider that is not kilometres but centimetres long. Dr Charlotte Palmer, University of Oxford, tells us how. However these fundamental questions are tackled, critics say that the money could be better spent on other research areas such as combating climate change. But supporters argue that its discoveries could uncover new technologies that will benefit future generations in ways we can’t predict. Anand Jagatia meets the scientists responsible to making this next giant leap into the quantum unknown. (Photo: CMS experiment at CERN, Switzerland. Photo credit: CERN)

Humans seem programmed to appreciate beauty - whether that’s an attractive face, a glorious sunset, or a stirring piece of music. Of course, our individual tastes are all different, and culture plays a huge part too - but why are we so struck by whatever it is we find beautiful? What is that pleasurable sensation we get when we see or hear something we like? And has the ability to appreciate beauty given us any evolutionary advantages? In a special edition of CrowdScience from the International Science Festival in Gothenburg, Sweden, we are joined by a panel of experts to explore how far science can explain the mystery of beauty. We look to biology, the brain, art and mathematics, to see how patterns, rhythms and symmetry contribute to our experience of beauty. And we ask whether machines can recognise or ‘appreciate’ beauty – and to what extent artificial intelligence is starting to confuse or influence what we think of as beautiful. Presenter: Marnie Chesterton Producer: Cathy Edwards Photo: A peacock. Credit: Getty Images/bobbieo

There are very good reasons to sleep: to regulate the body’s metabolism, blood pressure and other aspects of health. But do we actually need to dream? Is there an evolutionary reason for it? Marnie Chesterton takes her dream diary to a dream lab to explore this very popular preoccupation of many CrowdScience listeners. What would happen if we didn’t dream? What purpose do dreams serve? Can we really interpret them meaningfully, or are they merely random signals from the brain? The latest research says talking about them could be more important than we realise. And what about controlling our dreams? Marnie finds herself a willing participant in a study on lucid dreaming – of which sleep scientists are only just starting to understand the psychological benefits. Presenter: Marnie Chesterton Producer: Dominic Byrne (Image: Woman dreaming on a cloud up in the sky. Credit: Getty Images)

Swapping dairy milk for a plant-based milk is a growing trend that promises environmental benefits. But what is the best milk considering both our health and the planet’s? Scottish listener Nancy asks CrowdScience to unpick the pros and cons of plant-based milks. Presenter Graihagh Jackson digs into the research and finds that if the whole world were willing to swap dairy for soy, we would free up a land mass the size of Australia and reduce greenhouse gas emissions dramatically. So in theory the planet would be happier – but would we? Milk is packed with calcium and other nutrients that we humans need in our diet. And the ability to digest the sugar in dairy called ‘lactose’ is, according to evolutionary geneticist Mark Thomas, the most advantageous genetic mutation in human history. So can we live without it? Presenter: Graihagh Jackson Producer: Louisa Field (Image: A family enjoying milk at breakfast. Credit: Getty Images)

Cute isn't exactly a scientific term but we all know what we mean by it, don't we? Endearing, adorable, lovable and sweet. So what makes us fawn over a puppy, but run away from rats? Why do we spend millions on trying to keep Giant Pandas alive but spend even more on pushing endangered species like blue-fin Tuna to the brink of extinction by eating them? And if we changed what we classified as cute or ugly, how might that change the battle to protect the Earth's fragile biodiversity? CrowdScience listener Oleksiy, from Ukraine, wanted to know if cuteness is universal and what drives it? Seeking the answers, Marnie Chesterton cuddles puppies and enters a cramped spider nursery, seeking the science of cute, and exploring the evolutionary reasons for fear and disgust. Presenter: Marnie Chesterton Producer: Rory Galloway (Image: A cute and scary spider sitting on a green leaf. Credit: Getty Images)

Crowdscience heads to Africa's biggest science festival for a panel debate in front of a live audience that takes us into space then back down to earth to solve listeners' questions. Marnie Chesterton and Anand Jagatia are joined by aspiring extra-terrestrial, Dr Adriana Marais, who hopes to travel to Mars, along with cosmologist Palesa Nombula and sustainable energy expert Dr Sampson Mamphweli. They all explain how solving challenges on the ground will eventually help us set up home in space. Producers: Marijke Peters and Mel Brown Presenters: Marnie Chesterton and Anand Jagatia (Photo: Astronaut walking on Mars. Credit Getty Images)

A racing heart, blushing, feeling sick - most people experience symptoms of shyness in certain situations. But some of us are much shyer than others, and if it gets on top of you, shyness can really limit what you get out of life. That’s why this week’s listener got in touch with CrowdScience. He wants to know why he’s shy: is it genetic, or more to do with his upbringing? Is there anything he can do to overcome his shyness – and on the other hand, could being shy actually have some benefits? We find out how much shyness is down to our genes, and why ‘shy types’ might have evolved the first place. A psychologist gives us her top tips for dealing with social anxiety, and we take part in some drama therapy designed to help people break out of their shell. And we ask if quieter, more introverted types are disadvantaged in modern society, where outgoing, extraverted behaviour can bring more tangible rewards. (Photo: Shy young man hiding behind one eye. Credit: Getty Images)

This week we turn our gaze skywards to tackle three questions about what’s going on above us. Three year old Zac from the UK wants to know what clouds feel like – if they’re supposedly like steam, then how are they cold? Presenter Graihagh Jackson meets a meteorologist who can not only tell us but show us the answer, as we attempt to make a tiny cloud at ground level in the studio. Listener Agnese is looking beyond the cloud base and up to our nearest neighbour. She’d like to know why it is that we can see the Moon during the day. And Graihagh heads out to one of the longest-running and largest steerable telescopes in the world: The 76-metre Lovell Telescope at Jodrell Bank Observatory in the UK. Here, she finds out the answer to Sandeep from India’s extra-terrestrial question: Could aliens find us? (Image: Clouds in a blue sky. Credit: Getty Images)

The size of brains in the animal kingdom is wildly different, from melon-sized in blue whales to pea-sized in shrews. But does a bigger brain mean a more powerful one? CrowdScience listener Bob wondered just this as he watched various sized dogs running amok in his local park: the Great Dane has a much larger brain than a Chihuahua’s, yet the job of ‘being a dog’ surely requires the same brain power. So why have a big brain if a small one would do? A search for the answer takes Geoff Marsh to dog agility trials, behind the scenes at London’s Natural History Museum and a laboratory that studies bumble bees. It turns out that size does matter, but not in the way you might think. Presenter: Geoff Marsh Producer: Dom Byrne (Photo: Great Dane HARLEQUIN and a chihuahua Getty Images)

Our species started in Africa, but what was the last habitable landmass we reached? CrowdScience presenters Marnie Chesterton and Geoff Marsh team up to investigate how and when our species journeyed around the world and settled its most far flung landmasses. Geoff heads to some ancient caves in Israel to investigate the ‘false starts’ humans made out of Africa, and Marnie speaks with Professor Lisa Matisoo-Smith in New Zealand, uncovering the development of Polynesian sailing canoes and how they enabled the last landmasses to be found by people. This is a story spanning over seventy thousand years, huge changes in culture and technology, and the repeated remodelling of the earth thanks to the ice ages. Produced by Rory Galloway (Photo: Polynesian canoeists at sunset. Credit: Richmatts/Getty Images)

It’s the sort of plot you would expect from a classic sci-fi movie; what if there are viruses trapped deep in Antarctic ice that could wreak havoc on humans? Crowdscience presenter Alex Lathbridge puts on warm gloves and meets the scientists venturing into the icy wilds. He wants to answer listener Tony’s question - can viral life exist in such inhospitable climes and if so, might it pose us a danger? Alex meets teams who venture to the Antarctic to find out about how their work to understand climate change leads them to drilling and analysing ice cores that are tens of thousands of years old. He then visits a dynamic husband and wife duo in France who are extracting viruses from 30,000 year old Siberian permafrost and bringing them back to life. He discovers that - rather than killing us all, - their findings of novel giant viruses might contribute to medicine and our understanding of evolution. (Photo: Scientists working in a laboratory. Credit: Getty Images)

Waste, trash, garbage – whatever you call it, unwanted materials have become a major presence in many of our lives and our environment. Every year it is estimated that humans around the world produce 2 billion metric tonnes of waste. Listener Clare from Devon in the UK wants to start tackling this herself. She would like to know if she can not just sort but process all her own recycling at home. Presenter Marnie Chesterton attempts to find out by asking the professionals. She heads out to an industrial-scale recycling plant to see if any of their gear could work in our homes, hears from reporter Chhavi Sachdev how waste collectors in Mumbai, India have to balance thrift with risk, and asks environmental engineer Jenna Jambeck whether she thinks solely domestic recycling is possible. (Image: Garbage bags with various bits of recycling, iron, paper and plastic. Credit: Getty Images)

The ritual of burying the dead stretches back to the obscure beginnings of human history - and perhaps beyond, with archaeologists uncovering evidence of burials that pre-date our own species. But why do we bury our dead? How important is it, and how did the practice evolve? CrowdScience listener Moses from Uganda began pondering these questions after attending a close relative’s funeral. We search for clues in some of the earliest known burial sites, compare other methods for dealing with human remains, and explore how the funeral practices around the world today compare to those of our ancestors. Did these rituals originally develop for reasons of simple hygiene, or are religious and symbolic aspects the real key to understanding them? Presented by Anand Jagatia Produced by Cathy Edwards for the BBC World Service (Photo: A bereaved young woman in black, taking flowers to a grave. Credit: Getty Images)

When CrowdScience listener, Grady, crashed violently on his motorbike in the desert, he thought he was going to die. Years later he still can’t remember the dramatic seconds just before the impact. Where did the memory disappear to? Did the hard hit to the head knock his memories out or are they still in his brain somewhere? CrowdScience turns to brain science to find out if those last few seconds are lost for good or if the brain tells a different story. Under normal circumstances our brains like to hold onto memories that are emotionally important to us. We can remember our wedding day but not yesterday’s breakfast. But scientists have discovered that during near-death experiences, our brains are flooded with chemicals that disrupt our ability to remember. Grady may never recall how he was able to keep his motorbike steady as he drove off the road because – maybe – the memory was never created in the first place. Presenter: Marnie Chesterton Producers: Melanie Brown and Louisa Field Sound design: Eleni Hassabis (Image: A biker helmet lies on street near to a motorcycle accident. Credit: Getty Images)

Magma is the hot, molten rock found beneath the Earth’s crust. It’s so plentiful that it got Greek listener Dimitrios wondering whether we could harness this heat. Could we drill directly into the magma and use it to power our homes, he asks presenter Marnie Chesterton? And from Ghana, Madock also got in touch with CrowdScience to ask why there are lots of volcanoes in some areas of the world, but then none in others? Marnie dispatches Anand Jagatia to Kenya, a country that is one of the biggest providers of geothermal energy in the world and home to the East African Rift system. At 4,000 miles long, a string of volcanoes sits along this fault line. Anand hikes up one of these to find out why volcanism is so active here. Anand then travels to a geothermal power plant to get to grips with how conventional geothermal energy works, before turning to Iceland, where they’ve drilled directly into magma - albeit by accident. What they discovered was supercritical steam. It’s neither a liquid nor a gas but holds up to 10 times more energy than both. And to find it naturally occurring is the ‘holy grail’ of geothermal power. But can our equipment stand such temperatures? Presenter: Anand Jagatia and Marnie Chesterton Producer: Graihagh Jackson (Image: A volcano erupts. Credit Getty Images)

Birds are dinosaurs, but did their extinct relatives move, look, or even sing like their avian relatives? From revealing the hidden information within fossilised dinosaur footprints, to reading the messages left by muscle attachments on fossil bones and seeing how modern palaeo-artists have started to draw fluffy feathered Tyranosaurs, presenter Geoff Marsh starts to reimagine dinosaurs as living animals. Beginning with CrowdScience listener Malcolm asking about hopping dinosaurs while on a fossil finding mission with world expert Dr Peter Falkingham, Geoff explores the vaults of the Natural History Museum with Dr Susie Maidment and meets palaeoartist Dr Mark Witton’s pet dinosaurs in his living room studio. Producer: Rory Galloway (Image: A Velociraptor dinosaur. Credit to Mark Witton)

CrowdScience goes interstellar this week to answer listeners’ questions about the future of space travel. Marnie Chesterton heads to Nasa’s Kennedy Space Centre in Florida, where she hears about the engineering challenges of creating a spacecraft that could eventually take us all the way to Mars. Then there are the challenges of engineering the humans for that momentous journey. In space, no-one can hear you scream, which is probably a good thing if you’re going to be trapped in a metal box for two years with the same people, as you cruise through the void on your way to the red planet. So how do astronauts prepare for the physical and psychological impacts of long-term space travel? We also discover how space travel can be made greener and cleaner as the European Space Agency implement the next phase of their plan to tackle the millions of pieces of space debris floating around our planet that potentially, could impact a mission before it even leaves Earth orbit. (Image: An astronaut in outer space. Credit: Getty Images)

Wouldn’t it be great if you could lose weight and stay fit just by exercising your brain? Trouble is everything takes so much effort - from burning off excess weight to powering our cars. But why? Presenter Marnie Chesterton rummages through the CrowdScience inbox to tackle all your energy-expending queries. Is the entire universe spinning? How much energy do we expend when sleeping? Can I think myself thinner? Scientists Helen Czerski, Andrew Pontzen and Andrea Sella join listeners from around the world to discover how effort and energy affect our lives. (Image: A young boy sits at an office desk searching for successful ideas using a homemade thinking cap with a lit up light bulb. Credit: Getty Images)

Loving someone who doesn’t love you in return makes us feel wretched – can science explain why we must suffer? Parental love makes perfect evolutionary sense but romance just seems to have it in for us time after time. CrowdScience listener Leja wants to know why we fall in and out of love. Marnie Chesterton discovers the irrational things, the impulsive things and the financially ruinous things BBC World Service listeners have done in the name of love and meet the rapper who turned herself into a science subject in an effort to flush out thoughts of her ex-boyfriend. We delve into our ancestral past and into our brains to find out why romantic love is so central to the human experience. Presenter: Marnie Chesterton Producer: Louisa Field (Image: A loving couple hugging each other, the woman holding a rose. Credit: Getty Images)

From Russia to Rwanda, women live longer than men and have done so for over 100 years. But why? Is it encoded in our genes or is it something to do with the way we live? This is something CrowdScience listener Michelle from England has been wondering about. From cradle to grave, Marnie Chesterton examines the complex web of factors that are involved in how men and women age differently. It seems that, right from the word go, male embryos are already in the firing line because of their genetics. Marnie hears how women’s genetics are configured so that they have a backup copy of some of their genes, whereas men only have one copy. Not only does this make male embryos less resilient (and therefore more likely to miscarry), men are also at risk of a set of genetic diseases later in life like haemophilia. Puberty is an important component in this story too when a surge of hormones changes girls' and boys’ bodies into adults. But something in the way a boy develops sets them up for diseases late in life. They may be fitter, faster and stronger - all traits that were evolutionary important to make a man the alpha of the group - but this comes at a cost. For instance, the way that a man’s cardiovascular system is ‘configured’ means that they’re far more likely to have a heart attack than women. But it’s not just this, behaviour is also a really important factor and it’s why the gender gap in mortality differs from country to country. In Russia, the gap is nearly 13 years (the highest in the world) and it’s thought that a culture of heavy drinking and smoking is why women outlive men by more than a decade. ...which got Marnie thinking - could men change their destiny and outlive women? Presenter: Marnie Chesterton Producer: Graihagh Jackson (Photo: A group of ladies having coffee in modern café. Credit: Getty Images)

Removing carbon dioxide from our atmosphere - and stopping it getting up there in the first place - is becoming increasingly urgent if we want to prevent catastrophic climate change. There are some seriously high tech machines being developed to try and tackle this problem, but could an equally powerful solution be found in the dirt under our feet? Prompted by New Zealand farmer and CrowdScience listener Kem, we dig deep to see how effectively plants and soils soak up CO2 from the air; and what that means for how we should farm the land around the world. And we visit a Scottish forest to find out how the ancient art of making charcoal is staging a comeback in the fight against climate change. Presenter: Marnie Chesterton Producer: Cathy Edwards for BBC World Service (Photo: A young plant in soil, in the morning light. Credit: Getty Images)

We may take our ability to smell for granted but it’s a far more complex sense than many people realise. Listener Annabel wants Crowdscience to investigate why perfume makes her queasy, so Anand Jagatia sets out to discover why we can’t all agree when we follow our noses. He gets a whiff of the world’s stinkiest flower - and finds some people enjoy it – then asks what’s happening in the brain when we love or hate a scent. But could our different perceptions about this under-appreciated sense actually come down to a lack of words to describe it? He hears about one culture which has developed its own language for smell. Presenter: Anand Jagatia Producer: Marijke Peters (Image: A woman smelling roses. Credit: Getty Images)

Communicating quickly, accurately and, ideally, in a way that's well-received is no easy feat, wherever you live in the world. For this week's listener, who lives and works in several different countries as a member of the armed forces, good communication can be a matter of life or death. And this doesn’t just affect military life – anyone who flies on aeroplanes may be interested to hear how clear use of language is crucial for airline safety. But what do we mean by an efficient language – it is the fastest and most accurate speech, or most widely understood in multiple countries? Maybe there’s even some technology – a machine out there that can do the communicating more efficiently than we can? Presenter Marnie Chesterton attempts to apply science and evidence to the art of speech, in a quest to discover what language is the most efficient on Earth. Produced by Jen Whyntie (Image: A group of people holding up speech bubbles sitting on a bench. Credit: Getty Images)

From IVF to premature babies we explore what science we would need to make a baby outside the body in a pursuit to answer a question from Nigerian listener, Aminu asking: Can we make an artificial womb? To find out, presenter Nastaran Tavakoli-Far gets very close to a uterus transplant operation, peers at the earliest cells of a placenta, and sees a disembodied womb being kept alive in a box full of artificial blood. She asks how close current reproductive medicine brings us to gestating babies in a lab. Producer: Rory Galloway (Photo: A human fetus. Credit: Getty Images)

How should we tackle the biggest clean-up job in history? Listener Michelle from Ireland sends CrowdScience to investigate what to do with years’ worth of spent nuclear fuel. Most of the highly toxic waste is a by-product from nuclear power production and the stockpiles across the world continue to grow. “Could we blast it into the sun? Dilute it across the continent? Or should we bury it?” Michelle asks. We travel deep into the Finnish bedrock to visit what could be its final resting place and speak to the scientists who are securing the facility many ice-ages into the future. The nastiest stuff in the waste soup needs to stay put for thousands of years before it becomes safe. No man-made structure has ever before lasted so long. The Finnish solution is not easy to replicate in other countries as communities oppose nuclear waste being permanently buried in their backyard. Presenter Marnie Chesterton discovers that scientists have come up with solutions that could let us recycle the spent fuel more effectively, but it costs more than the industry is willing to spend. The clean-up job of the century comes down to dollars and not science. Presenter: Marnie Chesterton Producer: Louisa Field (Photo: a man in protective workwear in waste factory. Credit: Getty Images)

Mohammed is from India and he’s blind. He emailed CrowdScience because he wanted to know more about new technologies that could help him see again. Specifically, he was interested in artificial vision - what is it and what does it look like? Bobbie Lakhera travels to Germany to find out. There, she meets a blind patient called Manuel. He’s about to have a major operation. A computer chip will be implanted into his eye and his surgeon, Florian Gekeler, believes that it will restore some of Manuel’s sight. But what happens if you have no eyes for a chip like this to be inserted into? Bobbie speaks to Dr Nader Pouratian about his brain prosthesis. Because the implant is attached directly to the visual cortex of the brain, it means you could have no eyes or no optic nerve and you could still see with this type of therapy. Whilst both these technologies are limited to black and white vision, Bobbie asks whether one day we may be able to develop systems that give those living with blindness 20/20 vision. Presenter: Bobbie Lakhera Producer: Graihagh Jackson (Photo: A female iris, bionic eye concept. Credit: Getty Images)

When it comes to speed, humans have got nothing on cheetahs - or greyhounds, kangaroos or zebras for that matter. It’s over long distances we really come into our own: when running for hours or even days, our body structure and excellent sweating skills make us able to outpace much faster mammals. But what are the limits of human endurance? Can we run ever further and faster, and what’s the best diet to fuel such ambitions? This week’s questions come from two CrowdScience listeners in Japan who already know a fair bit about stamina, having run several marathons and long-distance triathlons between them. We head to Greece, legendary birthplace of the marathon, to witness an even more arduous challenge: hundreds of athletes following in the footsteps of the ancient Greek messenger Pheidippides, to run an astonishing 246km across the country. The ever-so-slightly less fit CrowdScience team do our best to keep up, and try to discover the secrets of these runners’ incredible endurance. Presenter: Marnie Chesterton Producer: Cathy Edwards (Photo: a runner in the Spartathlon ultramarathon, with kind permission from the International Spartathlon Association)

Would you willingly break a mirror, walk under a ladder or cut up an image of someone you love - or might you be worried about tempting fate – even if you don’t believe in supernatural forces? Anand Jagatia enters the world of magical thinking on behalf of CrowdScience listeners to explore why - even in this era of scientific rationalism – superstition, magic and belief in concepts like the evil eye and luck appear deeply entrenched in our cultures and psyche. Meeting historians and psychologists, Anand sets out to reveal the enduring lure of superstition and explore the biological factors that can influence us, like how our brains have evolved to look for connections and find patterns in seemingly random events. Is it possible that some people are ‘lucky’ and can we enhance our own ‘luck’? Experimental evidence is thin on the ground but finger’s crossed, CrowdScience can find some. Presenter: Anand Jagatia Producer: Melanie Brown (Image: A handmade Voodoo Doll with pins. Getty Images)

As the US reaches the end of another hurricane season listener Kelly wants to know if it’s possible to prevent these devastating storms? She lives in Florida, the hurricane capital of the world, and has survived 100mph winds whipping through her home. But could science hold the solution to these extreme weather events? Marnie Chesterton had the unique opportunity to fly into hurricane Florence with the weather scientists gathering data that helped forecasters predict its path, and reports from on board a plane near the eye of the storm. She hears from one researcher who wants to ‘whiten’ clouds to lower sea temperatures and reduce hurricane formation but learns others fear interventions like this could have unintended consequences elsewhere. Presenter: Marnie Chesterton Producer: Marijke Peters (Photo: Hurricane between Florida and Cuba. Credit to: NASA and Getty Images)

As the show that takes your questions and turns them into audio adventures reaches its 100th episode, Marnie Chesterton revisits a few of our most liked, talked-about, and inbox-filling programmes to find out how science is getting on with the answers. Marnie heads to a place where important queries have been tackled for hundreds of years - the University of Cambridge in the UK - to chase down some burning follow-ups on topics that have piqued your interest. She finds out what the future holds for the next generation of batteries as they're expected to power everything from smart phones to your car and even your house. Then she scrubs up to tackle your tough questions on the best ways to keep clean. Finally, Marnie visits a memory laboratory at Cambridge University to discover whether the very process of asking questions might be one way to help us remember more. (Photo: A woman from a group raises her hand to ask a question. Credit: Getty Images)

This violent and repetitive involuntary constriction of the chest muscles is highly infectious, and can result in convulsions, profuse tears and a reddening of the face. People are known to clutch their chests or roll around on the floor during the more intense bouts. Buy why? It seems a particularly odd thing to do and that’s why CrowdScientists, Erin from Australia, Geraldine from Switzerland, and Musweu from Zambia wanted to find out more about laughter. In pursuit of an understanding of what laughter is, and why we do it, Geoff Marsh attempts to distinguish the sounds of friends from strangers laughing together, and explores the earliest origins of this rib-rending behaviour. In the process he discovers that we’re not alone in laughing, and uncovers the importance of this ability for making and maintaining friendships. Presenter: Geoff Marsh Producer: Rory Galloway (Photo: Two young girls eating an ice-cream and Laughing. Credit: Getty Images)

E-cigarettes and vaping may only have been around for a decade or so but it's estimated more than 35 million people globally have taken it up. Marnie Chesterton heads to a vape show to discover why these gadgets are proving so popular, and hears from one expert who warns they could be damaging lung immune cells. She examines the research behind claims that e-cigarettes can help smokers quit, and finds conflicting evidence about how good they are at giving people the nicotine hit they crave. It's a research field that's in its infancy and with vaping technology constantly changing, it's little wonder some scientists say it's a struggle to keep up. Presenter: Marnie Chesterton Presenter: Marijke Peters (Photo: A woman smoking an e-cigarette. Credit: Getty Images)

Have you ever been out driving and noticed your mind… wandering? CrowdScience listener Sian Gardiner has. When travelling to visit her parents she has to cross a very large, very obvious bridge. But there are times when she finds herself on the other side with no memory of having gone over it. How is that even possible? Presenter Geoff Marsh buckles up to find out. He travels through the science of how driving becomes second nature, brakes sharply when he realises he’s not necessarily in conscious control at 70mph, and tries to refocus when he discovers why drivers don’t always see things that are staring them in the face. He also asks what’s happening when our mind drifts away from the road, and what can be done to help drivers pay more attention and reduce accidents. Presenter: Geoff Marsh Producer: Anna Lacey Sound design: Peregrine Andrews (Photo: A woman sits in her car, looking through window glass with rain drops. Credit: Getty Images)

In humans if you have two X chromosomes you are female and if you have an X and a Y then you are male. It is textbook science. But CrowdScience listener Du in Singapore has done some extra homework and found a piece of intriguing fish research which suggests a different outcome, at least for one species – tilapia, a popular fish on restaurant menus worldwide and as it happens, the first fish to visit space. Whilst humans couldn’t exist without an X-chromosome, tilapia apparently, can. In fact, they are happy with just two Y chromosomes. The existence of this odd breed comes down to the tilapia fish’s ability to change from male to female. Nature has come up with an array of bizarre solutions when it comes to sex determination and what sets you on one genetic path or another. And like with the tilapia fish, the decision isn't always for life. Some species of fish, lizards and even birds sidestep the chromosome system and morph between the sexes to survive a changing environment. How can they have both genetic sex pathways latent within them? And why can’t humans do the same trick? Presenter: Marnie Chesterton Producer: Louisa Field (Photo: A male Asian sheepshead wrasse courting a female featured in BBC’s Blue Planet II. Credit: Getty Images)

It’s the central question for the current generation of Mars missions. Since the first close-up pictures of the red planet back in 1965, decades of space missions have revealed our neighbouring planet to be cold, rocky and sterile. But there are hints of a more dramatic past; of raging volcanoes and flash floods. Could this be a planet where life existed? Could life still exist under the surface? And could humans live there, or even travel the distance to get there safely, at some point in the coming decades? CrowdScience listeners from Australia, Ghana and Canada have been musing on all sorts of Martian matters. Presenter Marnie Chesterton visits a corner of Stevenage, UK, with a distinctly unearthly appearance and takes a virtual tour of the Martian atmosphere. She also puts listeners’ questions to the scientists designing the spacecraft and instruments they hope will unlock the secrets of Mars. (Image: illustration of Mars shot from space. Credit: Getty Images)

The idea of creating underwater habitats has captured the imagination of writers, thinkers and scientists for decades. However, despite numerous grand visions, these dreams of aquatic metropolises have not yet come to fruition. Crowdscience listener and scuba enthusiast Jack wonders whether - given improved technology and the growing environmental pressures facing humans on land - it is time to reconsider the ocean as an alternative permanent living space for humans. Marnie Chesterton dons her flippers for Crowdscience in search of the oceanographers and architects who have dedicated their lives to designing vessels, labs and underwater habitats. She explores whether oceanic cities remain a sci-fi dream or a realistic solution to some of our modern challenges. Can the oceans’ largely unexplored resources be harnessed to support living underwater? (Photo: Illustration of a modern city under the sea. Credit: Getty Images)

What is light and can we trap it in a box? On this edition of CrowdScience, Marnie Chesterton brings you a kaleidoscope of colourful questions from listeners around the world, from Kampala to Chicago. Shireen asks why people have a favourite colour and whether other animals show colour preferences too. Marnie heads to the zoo to see what the birds, bees and butterflies think. There, she meets a colour-changing chameleon to find out how and why it does because of a question from Dramadri in Uganda. Meanwhile, Paul in Melbourne is interested to know more about colour blindness. And finally, Feroze asks why we only see a portion of the electromagnetic spectrum and wants to know if we might, one day, hack our vision to see beyond the seven colours of the rainbow. Presenter: Marnie Chesterton Producer: Graihagh Jackson (Photo: Stardust and magic in a woman hands on a dark background. Credit: Getty Images)

Hedgehogs are the UK’s favourite British mammal. They have cute furry faces, a snuffly nose and the ability to gobble up garden slugs. What’s not to like? Answer: quite a lot if you live in the Outer Hebrides. Hedgehogs were introduced to South Uist in the 1970s as garden pest controllers, but are now serious pests in their own right – munching their way through the eggs and chicks of globally important wading bird populations. This emblem of cuteness is really a killer. So what’s to be done? That’s the quandary facing this week’s CrowdScience thanks to a question from Juan Carlos in Cuba. He wants to know how different parts of the world are dealing with invasive species – one of the biggest threats to global biodiversity. Presenter Anand Jagatia heads to the Uists to hear how having an invader that’s loved by millions can cause a whole host of problems. He also discovers how various warring parties eventually came together to solve this very prickly problem. Also in the programme, Anand travels to South Africa to find out how researchers are coping with invasive trees by introducing another non-native species. While in the Caribbean, we hear how people are dealing with invasive fish by eating them. Presenter: Anand Jagatia Producer: Anna Lacey (Photo: A European hedgehog. Credit: Getty Images)

Teenagers are known for ignoring their parents’ advice, but is this reputation for rebellion well-founded? If so, is rejecting the advice of previous generations and treading our own path an important part of what it means to be human? Are we successful as a species precisely because of our questioning natures? Listener Hans started pondering these questions after his own adolescent children repeatedly ignored his nagging. Many animals simply follow in their parents’ footsteps – so what makes human children different? Marnie Chesterton and a panel of experts look at the science of taking advice and making decisions, finding out how human curiosity and exploration compare to other animals, learning the best ways to give and take advice, and seeing whether we’re more likely to trust artificial intelligence than the wisdom of our elders. Finally, we give listener Hans some expert advice on whether or not to keep nagging his kids. Presenter: Marnie Chesterton Producer: Cathy Edwards (Image: A father and son having communication issues. Credit: Getty Images)

This deceptively simple question from listeners Andy, Mike and James is actually one of the hardest questions CrowdScience has ever tackled. Why? Because even scientists struggle to explain the true nature of the magnetic force and to do so in a way that even presenter Marnie Chesterton can understand is a serious challenge. What is a magnet? And just what is going on when magnets exert a force? With the help of Melanie Windridge, Sean Giblin, Steve Bramwell, Charlotte New and Peter Morris we attempt to navigate the oddities of one of the most fundamental phenomena in the universe. (Image: A horseshoe magnet attracting some hammer nails. Credit: Getty Images)

Anand Jagatia heads to the rainbow nation of South Africa, to answer listener Lucy’s deceptively simple question. He follows the path of early human migration to understand the relationship between light skin and latitude, and find out how the world become more multi-coloured as people ventured further away from the equator. And he learns how our genes have helped us adapt to less sunny environments, hearing from the remote KhoeSan tribe in the Kalahari desert, who took part in a massive study aimed at giving scientists a better understanding of pigmentation. Producer: Marijke Peters Presenter: Anand Jagatia (Image: Four diverse women’s arms holding each others wrists in a circle. Credit: Getty Images)

Listener Pogo wants to know why there aren’t any cabbages – or any of the other vegetables – in his local forest. Where did they all come from? And could they someday disappear? Presenter Gareth Barlow goes hunting for wild snacks in a city park and unearths the evolution of our most beloved greens. The vegetables on our supermarket shelves today were not always nicely wrapped and tasty. Humans have been selecting for specific genes in plants for thousands of years by choosing to grow those we liked the most. Tomatoes have been transformed from a small prickly desert plant in Peru into a water guzzler with round, juicy, sweet fruits. But with breeding – and sometimes cloning – of plants we have also created genetic bottlenecks in many of the crops we rely heavily on. This has left many of our vegetables across the world vulnerable to shifts in climate, natural disasters, wars and diseases. To find solutions to this massive breach in food security, CrowdScience heads to the Millennium Seed-bank in England. By collecting and storing our most precious seeds in vaults beneath the ground, scientists are protecting the genetic diversity that we will need to overcome the challenges ahead. Presenter: Gareth Barlow Producer: Louisa Field Picture: Man holding basket of vegetables Credit: Getty Images/valentinrussanov

Sex – for most organisms - is about meeting the right partner. But what if you and your mate are stuck far apart with no ability to travel? This dilemma could put a bit of a downer on your sex life, but is faced by plants everywhere. Presenter Anand Jagatia uncovers the happy fact that not only have plants overcome this problem, they positively excel at it. From hay fever to honey, the sexual strategies of plants affect us daily, and we couldn’t live without their success. In this episode, CrowdScience is answering the questions you sent after a previous episode entitled ‘Can plants talk?’ which explored the way plants and trees use a fungal network to communicate. This time, we explore how plants ‘feel’ bees as they fly past, and more complex communication involving the ‘wood wide web’. Presenter Anand Jagatia Producer: Rory Galloway (Image: A yellow dandelion flower attracts a pollinator in the evening sunlight. Credit: Getty Images)

Some of the biggest reserves of freshwater are right under our feet and they're really important for farming as well as providing us with water to drink. However, in some areas of the world, groundwater is being slurped up quicker than it can be replenished. In fact, about 1.7 billion people live in regions where groundwater is under stress, 60% of them in India and China. This figure is set to rise as the climate changes and as the population grows. CrowdScience listener Waheed from Afghanistan wants to know if we will run out of groundwater and what the repercussions might be. Marnie Chesterton trots around the globe to find out, starting with a row on the River Thames before hearing from Afghanistan to understand what’s happening where Waheed lives. She learns of what has happened to London, Mexico and Malta when they over pumped their aquifers. Finally, Marnie looks to Bangalore where the population is booming to understand how they’re coping with increasing demands on water. Presenter: Marnie Chesterton Producer: Graihagh Jackson (Image: Children holding their hands up - asking for drinking water. Credit: Getty Images)

What sounds heavenly to one person might sound like boring noise to another - but why are our musical preferences so different? Is it all down to what we hear growing up, or are other factors at play? CrowdScience listener and music lover Jocelyne from Canada wants to know why she has a different song for every mood, and why she likes different music from her friends and family. Meanwhile in Italy, composer Elisabetta Brusa asks us whether the rules of harmony align with the laws of science, and should therefore not be broken. We talk to both musicians and neuroscientists to explore the truth about harmony and discord. We find out how age, personality and experience all affect whether we find certain songs pleasing or offensive, and learn why the search for the true universals of music pleasure is a race against time. Presenter: Marnie Chesterton Producer: Cathy Edwards (Image: A couple laying in the grass listening to music on headphones. Credit: Getty Images)

Hypnosis has a long and controversial history, with its roots in animal magnetism or mesmerism, the theory developed by 18th Century German doctor Franz Mesmer. He believed he had discovered an invisible natural force possessed by all living things, and that he could channel this force for healing purposes. Popularity of hypnosis has since waxed and waned, but was largely denounced as quackery until the 20th Century, when it began to be studied scientifically. However it is only in the last twenty years or so that is has become incorporated into mainstream science and medicine. But is it a real phenomenon, asks listener Gratian from Poland; and Anton from Ireland wants to know how it works and what happens to people’s brains and bodies under hypnosis? CrowdScience speaks to Dr Quinton Deeley, consultant psychiatrist and senior lecturer at the Institute of Psychiatry, who has used it in practice for many years, and Dr Amir Raz, a magician-turned-neuroscientist who is shedding light on how hypnosis works. To see how hypnosis is being used clinically, CrowdScience visits the Berkeley Clinic in Glasgow, Scotland, to witness a hypnotised patient having a tooth extracted with very little anaesthesia. Meanwhile, presenter and self-confessed arachnophobe Nastaran Tavakoli-Far takes part in the Friendly Spider programme at London Zoo, an afternoon event that uses hypnotherapy and group therapy to ease or eliminate the fear of spiders. Presenter: Nastaran Tavakoli-Far Producer: Helena Selby (Image: A silver pocket watch swinging on a chain on a black background to hypnotize. Credit: Getty Images)

Electric cars are labelled as ‘zero emissions’ vehicles – but what does that really mean? Jack Stewart puts your questions about EVs to the experts. According to a new report by the Union of Concerned Scientists, just how green your EV is compared to a petrol or diesel vehicle, depends on how the electricity powering the battery was produced, as well as how cleanly the battery itself was manufactured. Jack also explores what could be a compelling alternative to plugging in – filing up with Hydrogen, and creating nothing but water as exhaust. Presenter: Jack Stewart Producer: Rami Tzabar (Image: Electric cars on charge. Credit: Getty Images)

For some it's a way to get closer to God, for others a tried and tested way to lose weight - but listener Amine wants to know if fasting has any other, unexpected health benefits? So presenter Marnie Chesterton cuts down on cookies and investigates the science behind low-calorie or time-restricted eating. She hears how some cells regenerate when we're deprived of food, which one researcher says could reduce breast cancer rates. And she finds out what happens in our brains when our bodies rely on our own fat reserves for fuel. Presenter: Marnie Chesterton Producer: Marijke Peters (Image: Clock on an empty plate. Credit: Getty Images)

Why is it that computers are so much faster than brains at some tasks? Or could human brains one day be used to better effect? Listener Praveen from India was wondering how it can be that supercomputers are so very powerful compared to the human minds that created them. So CrowdScience, with the help of a small voice-activated guest presenter, is off to discover how the first computers remembered what they were told, how a million processors are being connected together to mimic a small percentage of a human brain, and how the mind-boggling speeds of modern computing is enabling the current leaps in artificial intelligence. Producer: Alex Mansfield Presenter: Marnie Chesterton Speakers: Sarah Baines, David Lewis - Museum of Science and Industry, Manchester James Sumner, Steve Furber - University of Manchester Aldo Faisal - Imperial College, London. (Photo: 3D transparent human head and brain image. Credit: Getty images)

Kenyan listener Docktor can’t help himself. When music is playing he must move to the beat and he wants to know why. What role does dance play in human evolution? And what does dance mean to us? To help answer the many twists and turns in Docktor’s questions, the CrowdScience team heads to one of the most vibrant and diverse dance scenes in the World, Havana in Cuba. For Cubans dancing is at the heart of their cultural identity. They tell stories, bond with others, practice religion and celebrate their African ancestry through dance ¬– which came to Cuba with the slave trade. For all humans, dancing is intimately connected to our love of music and is likely to be one of our oldest cultural practices. But why would our ancestors have wasted energy on what superficially seems to serve no survival benefits? Evolutionary anthropologist Bronwyn Tarr tells us that one clue lies in the brain. When we dance with others our brains reward us with a cocktail of feel-good hormones and this likely leads to profound social effects. Presenter Anand Jagatia gets challenged on the dance floor, discovers how deeply rooted dance is in Cuban society and why we should dance more. Presenter: Anand Jagatia Producer: Louisa Field (Image: Dancers in Cuba)

Humans have the potential to eat pretty much anything – but the reality is we don’t. Wherever we live in the world, we eat just a small fraction of the foodstuffs available and show strong preferences for certain foods over others. Those preferences can change dramatically from person to person, or as the saying goes – one man’s meat is another man’s poison. Then at the extreme end of the spectrum you get so-called ‘fussy eaters’ who reject so many foods that they are confined to beige diets of crisps, crackers and cereal. So why do we show such different preferences for food? And why are some people fussier than others? That’s what CrowdScience listeners Orante Andrijauskaite in Germany and Anna Nicolaou in Belgium would like to know, and what Datshiane Navanayagam is off to find out. She discovers how both biology and culture shape whether a food is disgusting or delicious and learns why we should stop giving children a hard time about finishing their dinner. She also learns how global cuisines evolved and what that can teach us about helping fussy eaters to overcome their food fears. Presenter: Datshiane Navanayagam Producer: Anna Lacey (Photo: Fried Bugs in Bangkok night market. Credit: Getty Images)

Carbon dioxide levels are far higher than at any other point in human history, thanks to our reliance on burning fossil fuels. But having pumped huge amounts of CO2 into the air, are there ways to get it back out again? If so, where would we put it all? And the big question: can that help solve our climate change problem, or is it a distraction from the urgent task of reducing our emissions? When CrowdScience delved into ancient carbon dioxide levels last year, it sparked a flurry of emails from our listeners asking these questions and more, so this week we investigate our options for restoring equilibrium to our atmosphere. Since the CO2 came from deep underground - in the form of coal, oil and gas - can we put it back there? We travel to Iceland where they’re capturing carbon dioxide directly from the air - and turning it into rock. Presenter: Marnie Chesterton Producer: Cathy Edwards (Photo: Nesjavellir geothermal power plant in Iceland. Credit: Getty Images)

Short-sightedness is reaching epidemic proportions around the world. The way things are progressing, one-third of the world’s population – 2.5 billion people - could need glasses by the end of the decade. And scientists are beginning to understand why: children spend too much time indoors, bent over screens and books. Marnie Chesterton travels to Singapore, where rates of myopia are one of the highest in the world and to see how the government is curbing the condition with an array of tools, from eye-drops to sunshine remedies. She does so in the hope of better understanding whether screens are bad for children’s eyes, a question raised by a concerned Mexican father, Fernando, about his two-year old daughter. Presenter: Marnie Chesterton Producer: Graihagh Jackson (Photo: A little girl wearing headphones while using a digital tablet at home. Credit: Getty Images)

Will gravity on earth ever change? Why do insects fly towards the light? Is the plasma in a TV the same as plasma in a fusion reactor? Why are mosquito bites so itchy? What does the Higgs boson do for the Universe? In a Q+A special, Marnie Chesterton is joined by scientists Malcolm Fairbairn, Kate Lancaster and Erica McAlister to tackle a selection of questions from the CrowdScience inbox. Presenter: Marnie Chesterton Producer: Alex Mansfield (Photo: Alates insects light bulb and night. Credit: Getty Images)

Dementia affects nearly 50 million people worldwide – but doctors are still struggling to find a cure. CrowdScience investigates why this particular group of brain diseases are so hard to treat, from the difficulties around diagnosis to why the drugs just don’t currently work. In the absence of a medical solution is it time to take a new approach? As geneticists develop tests to predict who might develop brain disease, there are others focusing on better care for those who already have it. Presenter Bobbie Lakhera visits a village in the Netherlands helping sufferers live longer independently, and hears how music projects improve non-verbal communication. Presenter: Bobbie Lakhera Producer: Marijke Peters (Photo: Neurology research examining the neurons of a human head to heal memory loss or cells due to dementia. Credit: Getty Images)

Since the end of the 19th century, scientists have been predicting we would be eating a meal in a pill, but is it a serious answer to the world’s food problems? That’s what Australian listener Bridget is wondering and whether it’s possible to produce an artificial food source that can provide all the nutrients for healthy human life. With increasing urbanisation, diets are changing and estimates suggest food production will have to increase some 60 percent by 2050 to keep up with demand. But can we provide all that extra food with limited natural resources and traditional farming methods? First, Marnie Chesterton finds out what artificial food is currently available and whether the existing products are healthy. And while a meal in a pill might sustain our bodies, will it sustain our minds? The experience of eating involves so much more than simply taking in the right nutrients, as Marnie discovers at the Gastrophysics Chef’s Table, a restaurant and multi-sensory dining experience. On the menu is jellyfish, a possible alternative source of food for the future. It’s in plentiful supply in our oceans, but like eating insects, the thought of it may be disgusting to some, so Marnie explores how sensory-driven strategies can be used to make these food sources more appealing. CrowdScience also visits the future of farming: A hydroponic vertical farm called Growing Underground, which is built in World War Two air-raid shelters under London. Using LED lighting instead of sunlight, leafy vegetables grow very quickly and need very little space. With higher crop yields per square metre than traditional farming, vertical farms allow fresh produce to be grown in urban centres with less impact on the environment. Hydroponic farming is something the European Space Agency is also experimenting with as part of Project Melissa, which is developing a closed loop ecological system - using rats instead of astronauts - aimed at one day helping us grow fruit and vegetables on Mars. Listen to the podcast version of the programme to hear this interview. Producer: Helena Selby (Photo: Pills on a plate. Credit: Getty Images)

Listener Nikolai sends CrowdScience hunting through space and time with his deceptively simple question. Can we find perfect stillness? You are probably reading this sentence whilst standing or sitting still. So is it a daft question? We discover that there are no simple answers as we unravel the science of motion, which tells us that we cannot always trust our senses to tell us ‘the truth’ about the natural world. The ancient Greeks believed it was the sun that rises and sets each day and this idea remained until the 16th century astronomer Nicolaus Copernicus showed us that this an illusion – that we are the ones in motion, orbiting the Sun. Later, through the work of Isaac Newton and then Albert Einstein, scientists came to the conclusion that nothing in the universe can ever be truly still. Except perhaps, the fastest thing in the universe – light. Confused? Don’t worry, so is Marnie Chesterton who sets out to explore not just the science of stillness but also the physics of stopping. To satisfy listener Nikolai’s curiosity about motion in space, CrowdScience also travels to ESA’s European Space Research and Technology Centre in the Netherlands. Here we find out how you stop a space craft and hear the story of when things got prickly for astronaut Tim Peake and his crew when docking at the International Space Station. Presenter: Marnie Chesterton Producer: Louisa Field (Photo: Astronaut wearing pressure suit against a space background. Credit: Getty Images)

Are you the master of your own decisions? Independent-minded? A free spirit? Like it or not, the answer is probably no - as we are profoundly influenced by the people around us. But why do humans follow the crowd? CrowdScience listener Cath Danes wants to know and this week we are going to be giving her answers at the BBC’s Free Thinking Festival in Gateshead. Marnie Chesterton is joined by a crack team of neuroscientists and psychologists, who reveal the secrets behind our inner sheep. We also run an experiment to find out whether you should trust the wisdom of the crowds with life’s big decisions. Presenter: Marnie Chesterton Producer: Anna Lacey (Photo: A flock of sheep being herded in a pasture. Credit: Getty Images)

Unlike nuclear fission power stations, which leave harmful radioactive waste to be stored or disposed of for thousands of years, a nuclear fusion power plant would create precious little burden on future generations. The fuel source would be seawater, and the energy created limitless. Back in the 1950s, the technology to “tame the hydrogen bomb” seemed just a few decades away from practical deployment, and governments across the divide of the cold war shared the challenges, costs and laboratories. But to the outsider, it might look like progress has been slow. In 1997 the Joint European Torus at Culham in the UK set the world record for energy released from a controlled fusion reaction, but even that was less than the energy was put in. Keeping the plasma – the super-hot atoms of exotic types of hydrogen – at temperatures many times the temperature of the sun safely in place inside a magnetic field is not a trivial task. Last year construction of the International Experimental Thermonuclear Reactor, ITER, reached its halfway point at its huge home in France, and if all goes to plan it should produce its first plasma by 2025. The hope is that operational fusion reactions will take place within a decade after that, paving the way for its successor DEMO - which would actually generate electricity - to be built sometime before 2050. But in parallel with the big intergovernmental roadmap, in recent years a number of small commercial startups have joined the race to achieve commercial fusion energy. With their various different approaches and more ambitious timelines, will the private sector beat the publicly funded science to the goal? Presenter: Bobbie Lakhera Producer: Alex Mansfield (Photo of ITER Organization, with permission)

Humans have used dogs' excellent sniffing talents ever since our ancestors figured out that canine companions could help them track down their next meal. But what about other animals? Can they take us beyond the limits of our own senses? That's what CrowdScience listener Beth wants to know, so we obligingly try to sniff out some answers. After immersing ourselves in the world of insect senses at our local zoo, we visit an insect lab in Germany to find out whether sniffer bees could take over from sniffer dogs. And could ants help us fly the drones of the future? We meet the scientists trying to turn ant vision into computer code, to send robots into places GPS can't reach. Presenter: Nastaran Tavakoli-Far Producer: Cathy Edwards (Photo: A bee on a human finger. Credit: Getty Images)

A cacophony of singing and screaming creatures’ accents are explored to answer: Can animals of the same species from different places communicate with each other? Presenter Geoff Marsh tries to identify how different these calls really sound for CrowdScience. From wolves to birds to whales and chimpanzees, most animals use sound to communicate, but if groups in different places vocalise in different ways, they may not be able to communicate with others. CrowdScience questioner, Kitty, sets us on an exploration of the vast and varied world of animal communication with inspiration from her dog Monty. Presenter: Geoff Marsh Producer: Rory Galloway (Photo: Three wolves howling on a cold day. Credit: Getty Images)

From worms who time their mating ritual with an inner lunar calendar, to how full moons could cause cows to give birth early. Listener Andreas sends CrowdScience on a mission to separate fact from fiction. Presenter: Marnie Chesterton Producer: Marijke Peters Picture: The moon rises over Kadam mountain in Uganda, on January 31, 2018, during the lunar phenomenon referred to as the 'super blue blood moon'. Credit: Yasuyoshi Chiba / AFP / Getty Images

Scientists have been searching for dark matter for 80 years, so CrowdScience wondered whether they could find it faster. Armed with a boiler suit, hard hat and ear defenders, Marnie Chesterton travels over a kilometre underground into a hot and sweaty mine to see how we could catch dark matter in action. She investigates various theories as to what it might be with popping candy and gazes at galaxies to determine how we know it exists in the first place. But most importantly, she questions whether it really matters. And, as our Singaporean listener Koon-Hou askes, what impact would finding it have on our everyday lives? Presenter: Marnie Chesterton Producer: Graihagh Jackson (Photo: Finding dark matter could have galactic implications. Credit: Getty Images)

Carbon is special, but is it necessarily the unique building block of life in the universe? Science fiction has long speculated on non-carbon biochemistries existing in the universe – notably in the work of authors such as Isaac Asimov as well as in the popular American TV series Star Trek, which once featured a rock-munching, silicon-based life form called ‘Horta’. Marnie Chesterton explores the real science behind this intriguing idea and wonders whether in the current search for Earth-like planets elsewhere in the galaxy, we should be looking at completely different possible sets of rules when it comes to the hunt for life? Producer Alex Mansfield Presenter Marnie Chesterton (Photo: Saturn viewed from Titan moon. Credit: Getty Images)

How far can you see? A few kilometres down the road? Or do you struggle to see past the end of your own nose? Well one listener thinks he might be able to see 15 quintillion miles away... but can he really? Marnie Chesterton and Bobbie Lakhera are on the case for this week’s multi-question human body special. As well as delving into the power of vision, they also discover why male mammals have nipples despite not needing to breastfeed, and Marnie puts herself in a giant refrigerator in the name of finding out why some people feel the cold more than others. Presenter: Marnie Chesterton Producer: Anna Lacey

Meet the entrepreneurs turning bugs into food and get top tips on how to cook them. In this week’s episode we return to the topic of edible insects and the story of Kahitouo Hein’s caterpillar factory in Burkina Faso, West Africa. Kahitouo is trying to turn a traditional food like the shea caterpillar, available for just a few weeks a year, into a year-long sustainable staple for the whole population. We also put your questions about edible insects directly to the researchers in Burkino Faso. Discover the best way to cook a bug, explore the curious effects of hornet venom and find out whether eating insects is better for the environment then eating red meat. Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenter: Anand Jagatia Producer: Louisa Field (Photo: Worker at Kahit’s factory cooking caterpillars)

Most of us instinctively know when someone’s singing and when they’re talking. But since music and speech are both just sounds, how do our brains tell them apart? This week’s question comes from Eugene, a music teacher in Northern Ireland, who often hears music in people’s speech, and wonders why. Step forward, the ‘speech-to-song illusion’. This curious phenomenon means that when certain spoken phrases are repeated, they turn into music as if by magic. We talk to the Diana Deutsch, the scientist who discovered this illusion, and find out what it reveals about how the brain is adapted to understand both music and speech. But are some languages more musical than others? Many people around the world speak tone languages, where the pitch of a word affects its meaning. One such language is Dinka, spoken in South Sudan; we meet a Dinka speaker and hear how respecting the melody of the language is essential when writing songs. Presenter: Datshiane Navanayagam Producer: Cathy Edwards Dinka recordings courtesy of Elizabeth Achol and Anyang Malual (Photo:Young woman listening to music on yellow headphones. Credit Getty Images)

Dogs have been living and working with humans for thousands of years. But they’re much more than just pets. As any dog owner will tell you, the bond we have with our canine friends is often so strong that they feel more like family. So how is it that dogs have come to fit so seamlessly into human life? That’s what CrowdScience listener Peter Jagger in the UK wants to know, and Marnie Chesterton is off to sniff out some answers. She starts by revisiting a previous episode of CrowdScience based in Sweden, where she saw the dog-human bond come alive during a moose hunt. She then heads to the Dog Cognition Centre in Portsmouth to discover how a unique and often unconscious communication system helps our dogs to understand us. Finally, Marnie finds out about the fate of dogs that are no longer wanted by their humans. After thousands of years of domestication, can they ever live without us? Presenter: Marnie Chesterton Producer: Anna Lacey (Photo: Image of young girl with her dog, alaskan malamute. Credit: Getty Images)

Crowdscience revisits the evidence on the best forms of biometric identification. Earlier in the year we explored digital fingerprints, gait (walking style) recognition and iris scanners. Today presenter Anand Jagatia looks at systems which use your face and your voice to identify you. One airline is currently testing facial recognition in airports as a means of replacing your passport. Meanwhile, Anand tries to fool a speech recognition system that measures over a thousand characteristics of your voice in order to protect your identity. But will it be able to cope if you have a cold? Presented by Anand Jagatia Produced by Marijke Peters. Picture: Facial Recognition Credit: Getty Images

Reindeer castration, plants get chatty and more quirky science revealed in this Christmas special of CrowdScience where we will also be hearing from the people that make this series possible. That’s you – our listeners. CrowdScience has been on air for just over a year which means we’ve had over 60 adventures. Every time we put a show together there’s a heart-breaking process where amazing facts we wanted to share end up on the cutting-room floor. To celebrate the holidays we’ve gone scavenging for the best untold stories, edgy science facts and incidents from behind the scene. Presenter: Marnie Chesterton Producer: Louisa Field Picture: Reindeer in Snow Credit: Getty Images

It lurks behind sofas and collects in corners, apparently appearing from nowhere. But what is household dust? And should we bother sweeping it away? That’s what Australian listener Moshe wants to know and what Marnie Chesterton is off to find out for this week’s CrowdScience. She embarks on a mission to discover not only what dust is made of, but whether it poses any health risks. Although most people sweep it away without a thought, dust contains all sorts of secrets about our habits and everyday lives. Marnie finds out how dust can reveal the pets you keep, the chemicals in your surroundings, the location of your house and how fecal bacteria can uncover whether more men or women live in your home. Presenter: Marnie Chesterton Producer: Anna Lacey (Image: Woman Vacuuming Up Dust. Credit: Getty Images)

Trees are old – they transcend human generations – but are they the oldest living things on Earth? This story began in June 2017 when we explored a question sent in from CrowdScience listener William. Many of you got in touch after the programme with questions of your own. So we’re revisiting our trees programme but also exploring another question from listener James, who wants to know what, pound for pound or gram for gram, is the strongest animal alive on Earth today? Marnie Chesterton wrestles with one of them and – spoiler alert – it’s not a gorilla. Presenter: Marnie Chesterton Producers: Jen Whyntie (Photo: Kumbuka, a 15-year-old western lowland gorilla. Credit: Oli Scarff/Getty Images)

Dodos are dead, but are they gone forever? Reviving extinct species is a trope of science fiction, but real-life scientists are working on every stage of the problem today. Meeting scientists focused on uncovering ancient animal genomes, or reviving individual cells to conserve species still around, Marnie Chesterton seeks out whether new technologies might, just possibly, bring back the iconic dodo. But what would it take to bring back that most iconic of extinct species? Following listener Rachel’s question, CrowdScience gets to grips with the dodo’s past, and finds out what’s left of this iconic bird, meeting the scientists inadvertently piecing it back together. Presenter: Marnie Chesterton Producer: Rory Galloway Picture: An accurate reconstruction of nesting Dodos Photo Credit: Dr Julian Hume

How does technology affect how we fall in love? Crowdscience travels to India to answer listener Erin’s questions about the impact of the internet on our search for soulmates. We meet the traditional matchmaker who says her service provides security in an era of digital fraud. And ask whether computer algorithms are the best way to help people make permanent romantic connections? Presenter: Chhavi Sachdev Producer: Marijke Peters (Photo: A couple kiss while taking a selfie. Credit: Getty Images)

Some of us want to be up with the larks, while others are more like night owls. But is our preference down to our genes, or more to do with habits and surroundings? We set out to find the answers, inspired by a question from Kira, a night owl CrowdScience listener in Philadelphia, USA. Our daily, or circadian, body clocks are a hot topic of discussion at the moment - this year’s Nobel Prize for Medicine went to three scientists who discovered the gene that makes these clocks tick. To answer our listener’s question, we need to know why different clocks tick at different rates, so we visit a specialist sleep centre to see how having a slow-ticking clock makes it hard for you to leap out of bed in the morning. And the morning sun helps all of us regulate our daily rhythm, so what happens when it doesn’t rise at all? We travel to Tromsø, in the far north of Norway, to see how morning and evening types fare during the long polar nights - and meet the reindeer who seem to be able to switch off their daily clocks altogether. Meanwhile down near the equator, we hear about the hunter-gatherer community in Tanzania where there’s nearly always someone awake. Sami song, the joik of Ráikku-Ánte, is performed by Ken Even Berg Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenter: Anand Jagatia Producer: Cathy Edwards (Image: L - Women smiling on a run R - Women DJ. Credit: Getty Images)

Sometimes our memory fails us and we wish facts would just stick better. Listener Mothibi is a student and has spent three years trying to remember as much as possible for his exams. He wants to know how he can train his brain to better to remember things – and does the brain have a limit on how much stuff we can cram into it? To find the answers presenter Marnie Chesterton seeks help from memory magician, Simon, at the European Memory Championship. Using the loci technique she accomplishes a memory feat she didn’t think possible. Thought to have been developed by the Greeks, the loci method is a technique that enables the brain to remember extraordinary amounts of information. It turns out, we all have the right wiring to remember more and better, but we need to train our brains. Also, CrowdScience heads to Cambridge University where Marnie Chesterton lands herself in a study. The scientists scan her brain while she exercises her memory muscles and we discover why sometimes memories get muddled up. Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenter: Marnie Chesterton Producer: Louisa Field (Image: Woman scratching head, thinking brain melting into lines. Credit: Getty Images)

People often talk about being descended from apes. But go back a bit further and we have a more unlikely ancestor – fish. Improbable as it may sound, the creature that gave rise to every bird, reptile and mammal on Earth today lived a fully aquatic life. So how did it switch to life on land? And how hard was it to swap swimming for walking and breathing fresh air? That’s what CrowdScience listener Pierre in France wants to know, and what Marnie Chesterton is in Scotland to find out. She goes fossil hunting with members of the TW:eed Project team, as they try to uncover remains of creatures that are crucial in helping solve the puzzle of terrestrial life. She also discovers the landscape these early ancestors walked into – an alien and relatively empty world completely different to what we see today - where grass and flowers were yet to evolve. But not everything in this story is preserved in rock. Marnie goes to see a living relic of this period of evolution, and finds out what it can tell us about possibly the most important event in the history of our species. Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenter: Marnie Chesterton Producer: Anna Lacey (Image: Artists impression of underwater environment of Carboniferous swamp depicting a rhizodont; a large predatory fish. Credit: Mark Witton)

Unpleasant man-made noise is something that disturbs many of us and even damages our health. But as millions more people move into crowded cities around the world, it's a cacophony that we almost unavoidably create ourselves. CrowdScience listener Diana from New York City in the USA got in touch to ask how we can temper the din and live a more peaceful life. Presenter Anand Jagatia heads to an acoustics lab at the University of Salford in Manchester, UK, to meet the researchers and engineers investigating the best ways to make cities more pleasant for our ears whilst still maintaining the ‘buzz’ of city life. And reporter Chhavi Sachdev takes us to Mumbai in India, where we discover how sound mapping is being deployed on the city’s streets as the first step to improve the life and health of its citizens. Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenter: Anand Jagatia Producer: Jen Whyntie (Image: Children cover their ears as the truck convoy front passes. Credit: Getty Images)