CrowdScience

How do you think about the internet? What does the word conjure 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? We might not think of it at all, beyond whether we can connect our phones to it.Another chance to hear one of our favourite episodes, inspired by a question from CrowdScience listener Simon: how much does the internet weigh? First of all, this means deciding what counts as the internet. If it is purely the electrons that form those TikTok videos and cat memes, then you might be surprised to hear that you could easily lift the internet with your little 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 Presenters: Marnie Chesterton & Caroline Steel Editors: Richard Collings & Cathy Edwards Production Coordinators: Jonathan Harris & Ishmael Soriano Studio Manager: Donald MacDonald(Image: Blue scales with computer coding terms. Credit: Alengo via Getty Images)

Snakes are often seen as slithery, slimy and scary. But these intriguing non-legged creatures have made CrowdScience listener Okello from Uganda wonder how they move – more specifically, he wants to know how they climb trees so easily, and so fast. Presenter Caroline Steel meets snake expert Mark O’Shea to investigate the ingenious methods different snakes use to scale a tree trunk, and gets a demonstration from a very agreeable corn snake at a zoo.Snake movement isn’t just your typical S-shaped slithering: these reptiles move in a remarkably diverse range of ways. Melissa Miller from the University of Florida explains all the range of motion snakes can employ to effectively travel along the ground as well as at height.Caroline witnesses this in action as we pay a steamy visit to the Everglades National Park in Florida, USA, tracking pythons across the vast swamps there. We find out why understanding these pythons’ movement is vitally important for conserving the local ecosystem.Contributors: Dr Melissa Miller, Research Assistant Scientist, University of Florida Brandon Welty, Wildlife Biologist, University of Florida Prof Mark O’Shea MBE, Professor of Herpetology, University of WolverhamptonPresenter: Caroline Steel Producer: Hannah Fisher Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Neva Missirian

The CrowdScience team like a challenge. And listeners Jenny and Kai in the UK have come to us with a big one. They want to know how many flies have ever existed. Flies first appeared around 270 million years ago, so presenter Caroline Steel prepares herself to calculate a very, very large number indeed. She enlists the help of Dr Erica McAlister, Curator of Flies at the Natural History Museum in London. As Erica introduces her to specimens from the Museum’s collection of over 30 million insects, they start with the basics. Like... how do you define a fly in the first place?Caroline also explores the incredible diversity of flies… from fast-moving predators like robber flies which catch other insects on the wing to midges which are a vital part of chocolate-production; and from blood-sucking mosquitoes which transmit fatal diseases to the housefly buzzing lazily around a room. And that leads to another fly-related question. Listener Brendan in Colombia wonders why they always fly in circles around a particular area of his apartment. For an explanation we turn to Prof. Jochen Zeil from the Australian National University who reveals that this apparently aimless behaviour is, in fact, a battle for sex. And Collin in Barbados has e-mailed to ask how flies and mosquitoes benefit us. He’s had first-hand experience of their negative effects through contracting the disease chikungunya from a mosquito bite so he’s wondering if these insects are anything other than a nuisance. However, passionate fly advocate Erica McAlister is ready with plenty of reasons that we should be extremely grateful for them!Contributors: Dr Erica McAlister, Natural History Museum, London Dr David Yeates, Director, Australian National Insect Collection Prof. Jochen Zeil, Australian National University Prof. Jo Lines, London School of Hygiene and Tropical Medicine Presenter: Caroline Steel Producer: Jeremy Grange Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Sarah Hockley(Image: Close-up of insect on leaf, Kageshwori Manohara, Bagmati Province, Nepal. Credit: Aashish Shrestha via Getty Images)

It’s hard to imagine something as mind-bogglingly small as an atom. But CrowdScience listener Alan has been attempting to do just that. All things in nature appear to be different and unique; like trees and snowflakes, could it be that no two atoms are ever the same?Alan isn’t the first person to wonder this. Philosopher and scientist Gottfried Leibnitz had a similar idea in the 17th century; in this episode, philosopher of physics Eleanor Knox helps us unpick the very idea of uniqueness. And with the help of physicist Andrew Pontzen, presenter Anand Jagatia zooms into the nucleus of an atom in search of answers. Listener Alan has a hunch that the constant movement of electrons means no atom is exactly the same at any given moment in time. Is that hunch right? We discover that the world of tiny subatomic particles is even stranger than it might seem once you get into quantum realms.Can we pinpoint where uniqueness begins? And if the universe is infinite, is uniqueness even possible?In the podcast edition of this show, we peer into that expansive universe, as we discover that the quantum world of hydrogen - the tiniest and most abundant of all atoms - allows us to observe galaxies far, far away. Featuring: Dr Eleanor Knox – King’s College London Prof Andrew Pontzen – University College London Dr Sarah Blyth – University of Cape Town Dr Lucia Marchetti – University of Cape TownPresented by Anand Jagatia Produced by Florian Bohr Editor: Cathy Edwards Production Coordinators: Ishmael Soriano and Liz Tuohy Studio Manager: Emma Harth(Photo: Twelve snow crystals photographed under a microscope, circa 1935. Credit: Herbert/Archive Photos/Getty Images)

Listener Julie lives close to the coast in New Zealand and wants to know why the water that washes up on the beach isn't fresh. How exactly does all that salt get into the world's oceans? In India, a country where salt became symbolic of much more than well-seasoned food, host Chhavi Sachdev visits coastal salt farms and a research institute dedicated to studying all things saline, to better understand our relationship with salty seas. The team also ventures to a very briny lake on the other side of the globe in Salt Lake City, Utah, to learn how salt makes its way into water bodies. Speaking to an expert in deep sea exploration, we learn how hydrothermal vents may play a role in regulating ocean saltiness, and how much the field still has to explore. Meanwhile, listener Will wants to know how much melting ice sheets are affecting ocean salinity. But ice melt isn’t the only thing affecting salt levels when it comes to the impacts of climate change. And... how many teaspoons of salt are in a kilogram of sea water anyway? We do the rigorous science to answer all these salient saline questions. Featuring: Deepika - small scale salt farmer Mark Radwin - PhD candidate in geology and geophysics at the University of Utah Brenda Bowen - Geology & Geophysics, Atmospheric Sciences, University of Utah Chris German - Geology & Geophysics, Woods Hole Oceanographic Institution Prasan Khemka - Chandan Salt Works Paul Durack - Lawrence Livermore National Laboratory Bhoomi Andharia - Central Salt & Marine Chemicals Research Institute Presenter: Chhavi Sachdev Producer: Sam Baker Editor: Cathy Edwards Production Coordinator: Liz Tuohy Studio Manager: Sarah Hockley (Photo: Shiv Salt Works, Bhavnagar, Gujarat in India. Credit: Chhavi Sachdev, BBC)

CrowdScience listener Eleanor was lying in bed one rainy evening, listening to the radio. She lives in New Zealand, but happened to hear a weather forecast that told her it was raining in the UK too. She started wondering: could it be the same rain falling there and outside her window in New Zealand? Can a raindrop really travel all the way around the world? There are a number of routes the droplet could take, including traveling as moisture in the air. Presenter Caroline Steel meets meteorologist Kei Yoshimura, who puts his powerful weather simulation to work plotting the raindrop’s journey through the sky. What if the raindrop falls along the way and gets trapped? Where might it end up? Hydrologist Marc Bierkens talks Caroline through the detours it could take, ranging from short stop-offs in plant stems to extremely long delays in deep groundwater. Finally, could the drop of water make it to New Zealand by circulating through the world’s ocean currents? Oceanographer Kathy Gunn maps the droplet’s path through the ocean – and explains how climate change might affect its journey. Featuring: Prof. Kei Yoshimura, Professor of Isotope Meteorology, University of Tokyo Prof. Marc Bierkens, Professor of Earth Surface Hydrology at Utrecht University Dr. Kathy Gunn, Lecturer in Climate Sciences at the University of Southampton Presenter: Caroline Steel Producer: Phil Sansom Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy Studio Manager: Tim Heffer Additional recording: Knut Heinatz(Photo: Textures of rain on the surface of the ocean. Credit: Philip Thurston/Getty Images)

It’s often said that fine wine gets better with time, and this week’s oenophile listener Jeremy has a cellar full of dust-covered bottles. He is curious whether chemistry can account for the range of flavours that develop as wine matures, but also wonders why some of it tastes like vinegar if you leave it too long? We head off to the Bordeaux region of France, where vines were planted almost 2,000 years ago. Here, winemakers are joining forces with scientists to better understand wine ageing, a process so subtle and intricate that even the scientists refer to it as magic. In the world-famous vineyards of Chateau Margaux, presenter Marnie Chesterton learns that the key ingredient for good grapes is a sandy soil type; and that in this part of France, the warming climate is actually having a positive effect on the vines, which need very little water to thrive. Over in the lab, we meet the chemist mapping the molecules responsible for aromas associated with a well-aged Bordeaux. Featuring: Philippe Bascaules, Chateau Margaux Prof Cornelis van Leeuwen, Bordeaux Sciences Agro Dr Stephanie Marchand-Marion, ISVV Alexandre Pons, ISVV Presented by Marnie Chesterton Producer – Marijke Peters Editor – Cathy Edwards Production Co-ordinator – Liz Tuohy Studio Manager – Sarah Hockley(Photo: Aged bottles on wine racks in a cellar. Credit: Morsa Images/Getty Images)

The Blue Ridge Parkway is 469 miles of beautiful vistas, a mountainous road that winds from Virginia to North Carolina in the USA. The route is peppered with elevation signs, telling you how many metres above sea level you are. Which has CrowdScience listener Beth wondering: as we are told that sea level is rising, will all the elevation signs need repainting? It’s a task she’s passed over to the CrowdScience team, who like a difficult challenge. The height of an enormous pile of rock like Ben Nevis, or Mount Everest feels unchangeable. But we measure them relative to the nearest patch of sea, which is where our story becomes complicated. Unlike water in a bath, sea level is not equal around the world. The east coast of America has a different sea level to its west coast. And as host Marnie Chesterton discovers in Finland, in some parts of the world the land is being pushed up, so sea level is actually falling. In fact, when nothing on earth - not the sea, the shore or the mountains - seems to be stable or constant, the question of what you measure from and to becomes incredibly tricky. But that hasn’t stopped oceanography and geography scientists risking life and fingers to use an ever-evolving array of technologies to find answers. In this show we find out why they care so much, and why we should too.Featuring: Dr Paul Bell – National Oceanography Centre, Liverpool, UK Dr Severine Fournier – NASA Jet Propulsion Laboratory / California Institute of Technology Dr Jani Särkkä – Finnish Meteorological Institute Khimlal Gautam – Mountaineer and Chief Survey Officer, Government of Nepal Dr Derek van Westrum – National Oceanic and Atmospheric Administration, USAPresented and produced by Marnie Chesterton Editor – Cathy Edwards Production Co-ordinator – Liz Tuohy Studio Manager – Steve Greenwood (Photo: Sea Level Elevation Sign in Death Valley, California. Credit: Mitch Diamond/Getty Images)

Prayer and meditation are key features of religious and spiritual practices around the world, suggesting they’re intimately linked to the human condition. But what is going on in the brain during prayer? And is praying beneficial for our mental health? CrowdScience listener Hilary is keen to find answers to such questions. She’s a counsellor with a strong Christian faith, and is curious to know whether science can illuminate religious and spiritual practices. Presenter Caroline Steel talks to neuroscientists researching how our brains respond to prayer and meditation; and practices mindfulness herself to explore its similarities to prayer. She discovers that having a relationship with God may depend on more than religious practice. And is there a ‘spiritual part’ to our brains? Or is prayer just one activity among many - like going for a walk or playing music - that can have similar effects on our state of mind? Featuring: Professor Andrew Newberg, Director of Research Marcus Institute of Integrative Health, Thomas Jefferson University and Hospital, USA Tessa Watt, mindfulness teacher Ven. Hin Hung Sik, Centre of Buddhist Studies, University of Hong Kong Dr Junling Gao, Centre of Buddhist Studies, University of Hong Kong Dr Blake Victor Kent, Westmont College, USA Presenter: Caroline Steel Producer: Jo Glanville Editor: Cathy Edwards Studio Manager: Tim Heffer Production Co-ordinator: Liz Tuohy(Photo: A crowd of people praying. Credit: Digital Vision/Getty Images)

Mosquitoes are responsible for more human deaths than any other animal. These tiny creatures transmit many diseases, but the most devastating is malaria. It kills over half a million people every year, most of them children. So why are people still dying of malaria in such large numbers, when so much time and money has been invested in trying to eradicate it? What do we know about mosquitoes and malaria, and what do we still need to learn? CrowdScience visits Malawi, one of the African countries leading the way against malaria, with the rollout of the world’s first malaria vaccine programme. Presenter Caroline Steel is joined by a live audience and a panel of experts: Wongani Nygulu, Eggrey Aisha Kambewa and Steve Gowelo. Together they explore questions from our listeners in Malawi and around the world, like why female mosquitoes feed on blood while males drink nectar; why some people are more likely to be bitten by mosquitoes than others; and how we might modify the insects’ DNA to stop them spreading diseases. About half a million children across Malawi have been vaccinated since 2019. We visit a clinic in nearby Chikwawa to meet the staff involved in the vaccination programme there, and the mothers embracing the opportunity to protect their babies against this deadly disease. Recorded at Malawi Liverpool Wellcome Trust (MLW), Blantyre, Malawi. Contributors: Dr. Wongani Nygulu, Epidemiologist, Malaria Alert Centre Eggrey Aisha Kambewa, MLW entomologist, MLW Dr. Steve Gowelo, University of California San Francisco Malaria Elimination Initiative Presenter: Caroline Steel Producer: Jeremy Grange Researcher: Imaan Moin Additional Recording: Margaret Sessa Hawkins & Sophie Ormiston Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy(Photo: A mosquito, that is silhouetted against the moon, bites a human arm. Credit: LWA/Getty Images)

When CrowdScience listener Israel from Papua New Guinea received a bad grade on a maths test in third grade, he looked around the class and realised that almost all the other students had received a better result. Since then, he has always wondered: why are some people better at maths than others? And Israel isn’t the only one to think about this: our listeners from all over the world describe their relationships with numbers, which run the full gamut from love to hate. So are we all in control of our own mathematical fate, or are some people just naturally bad at it? Presenter Anand Jagatia hears about studies of identical and non-identical twins showing how genetics and environment interact to shape our mathematical abilities. Our numerical abilities are not set in stone. It’s always possible to improve, and getting rid of negative feelings and anxiety around maths could be the key, says psychologist Iro Xenidou-Dervou. Some countries seem to support children’s maths skills better than others. China and Finland both rank highly in international league tables; education experts in both countries discuss whether there are any keys to a successful mathematics education. And there is something underlying our ability to do maths in the first place: our number sense. We hear what happens when this number sense does not work as intended – and what can be done about it. Contributors: Professor Yulia Kovas – Goldsmiths University of London, UK Professor Pekka Räsänen – University of Turku, Finland Assistant Professor Zhenzhen Miao – Jiangxi Normal University, China Dr Iro Xenidou-Dervou – Loughborough University, UK Professor Brian Butterworth – University College London, UK Presented by Anand Jagatia Produced by Florian Bohr Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy Studio Manager: Jackie Margerum (Photo: Boy scratching head in front of blackboard. Credit: Jose Luis Pelaez Inc/Getty Images)

Coastlines around the world are changing, causing serious problems for the many communities living near the sea, as well as vital and fragile coastal ecosystems. In the second of a two-part special on coastal erosion, CrowdScience explores the best ways to tackle this problem. Presenter Caroline Steel visits the Caribbean island of Puerto Rico to see the various methods they use to protect their coasts. First up: ‘riprap’ – rocks strategically placed to keep the encroaching sea at bay. The problem is, while it protects the area immediately behind the rocks, riprap can exacerbate erosion nearby. But there are other, more nature-friendly solutions, including sand dune restoration. Caroline picks up her shovel and helps to re-plant dunes, destroyed in the past by erosion as well as sand extraction for the construction trade. The roots of these plants stabilise the dunes, while building boardwalks prevents further damage from humans. Nature also offers the perfect offshore protection against coastal erosion: coral reefs. These are the first line of defence in absorbing the power of the ocean’s waves. Down on the beach, we see for ourselves just how effective they are. The reefs face threats, but restoration plans are afoot. We visit a nursery that grows corals to plant out on the reefs – and find out about corals’ surprising cannibalistic tendencies in the process. Featuring: Professor Robert Mayer - Director of Vida Marina, Center for Conservation and Ecological Restoration, University of Puerto Rico Nada Nigaglioni - Biology student, University of Puerto Rico Ernesto Diaz - Caribbean Regional Manager at TetraTech Dr Stacey Williams - Executive Director, ISER Caribe Presenter: Caroline Steel Producer: Hannah Fisher Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy Studio Manager: Emma Harth(Photo: Coast restoration measures at Ultimo Trolley Beach, Puerto Rico. Credit: BBC)

Around the world, coastlines are constantly changing due to the power of waves, currents and tides. Coastal areas are also some of the most heavily populated and developed land areas in the world. So it’s not hard to see how the natural process of coastal erosion can cause serious problems for us. It’s an issue that’s been bothering CrowdScience listener Anne in Miami Beach, Florida. She can see the beach from her window and wonders why after every storm, several trucks arrive to dump more sand on it. In this first of two programmes, CrowdScience visits Anne’s home in south Florida and finds out how erosion threatens Florida’s famous beaches. Caroline Steel speaks to geoscientist Dr Tiffany Roberts Briggs and hears why it’s such a problem for this tourist-reliant state. Tiffany explains the delicate balance between natural processes and human infrastructure. Meanwhile, the Caribbean island of Puerto Rico declared a state of emergency in April 2023 due to coastal erosion. Caroline witnesses the impacts of erosion first-hand, as Ruperto Chaparro shows her abandoned houses crumbling into the sea. But how can we quantify the rate of erosion? Dr Kevian Perez in the Graduate School of Planning at University of Puerto Rico explains the methods they use to monitor Puerto Rico’s coastlines, and how they are evaluating the effectiveness of different mitigation methods. However, some of the methods used to protect coastal communities from the encroaching sea have done more harm than good. So what are the best ways to tackle this problem? That’s what we’ll be exploring in next week’s programme. Presenter: Caroline Steel Producer: Hannah Fisher Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy Studio Manager: Steve Greenwood and Bob Nettles Featuring: Dr Tiffany Roberts Briggs, Associate Professor at Florida Atlantic University Ruperto Chaparro, Director of Sea Grant Programme, University of Puerto Rico Anabela Fuentes Garcia, Villa Cristiana community leader Dr Kevian Perez, researcher at the Coastal Research and Planning Institute of Puerto Rico at the Graduate School of Planning(Photo: Puerto Rico after Hurricane Maria. Credit: Orlando Sentinel/Getty Images)

How do we know where a sound is coming from? Another chance to hear this ear-opening episode, exploring a question from CrowdScience listener Chiletso. One day, he heard his son bounce a ball and instantly knew the direction it was travelling. How? Anand Jagatia sets out to discover what makes left, right, up and down sound so different. First, he gets blindfolded, so 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. This programme was originally broadcast in March 2023. 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

Today there are over eight billion people on Earth. That’s an awe-inspiring figure… but how does it compare to the vast numbers who came before us? Listener Alpha wants to know how many people have ever existed, so CrowdScience sets out to do a historical headcount.The Population Reference Bureau in the USA estimated this number back in the 90s, and have been updating their calculations ever since. Demographer Toshiko Kaneda explains how their model works, the assumptions it makes – and the huge uncertainties around the number it comes out with.We first need a date for when ‘humans’ first began, so Caroline travels to the Natural History Museum in London to meet human evolution expert Chris Stringer, and marvel at his collection of replica fossil skulls. Chris demonstrates how to distinguish our species, Homo sapiens, from other species like Neanderthals. When did these species first appear - and which of them count as human?And once you know where to start the clock, how do you estimate the numbers of people alive at different points in history? For a population demographer like Walter Scheidel, it helps that some ancient civilisations kept detailed censuses, a few of which have survived to the present day. Caroline and Walter pour over one of these census fragments, and learn how to combine them with other archaeological clues to get some very rough numbers.And finally: what does the future of our population look like? Poonam Muttreja from the Population Foundation of India discusses developments in the world’s most populous country, as well as the big demographic trends ahead for humanity. Presenter: Caroline Steel Producer: Phil Sansom Additional Recording: Umaru Fofana Editor: Cathy Edwards Production Co-ordinator: Connor Morgans Studio Manager: Sue Maillot Featuring: Toshiko Kaneda, Technical Director of Demographic Research, Population Reference Bureau Chris Stringer, Research Leader in Human Evolution, Natural History Museum London Walter Scheidel, Professor of Classics and History, Stanford University Poonam Muttreja, Executive Director, Population Foundation of India

We spend a lot of our time thinking about climate change, but listener Paul has a question that isn’t usually part of the conversation. He wants to know whether a hotter atmosphere will affect how often volcanoes erupt, or make them more explosive when they do.CrowdScience travels to New Zealand to search for answers, exploring volcanic craters and discovering traditional Maori knowledge about volcanoes.Contributors: Geoff Kilgour, Volcanologist, Geological and Nuclear Sciences Taupo, New Zealand Heather Handley, Volcanologist, University of Twente, The Netherlands Pouroto Ngaropo, Historian and Matauranga Māori expert, Rotorua, New Zealand Presenter: Caroline Steel Producer: Emily Bird Editor: Cathy Edwards Production Co-Ordinator: Connor Morgans Sound Engineer: Steve Greenwood(Photo: Icelandic volcano. Credit: KRISTINN MAGNUSSON/Getty Images)

Many of us have habits that calm us down in times of stress. Things we find deeply comforting, like sucking our thumb or biting our nails. We might not even be aware we’re doing them, but they play a fundamental role in helping us regulate our emotions. Our question this week comes from CrowdScience listener and nail-biter, Ash. He wants to know where these habits come from. And since his pet dog is also a nail-biter: do we share these traits with other animals? Recently, a video of a mouse cleaning up a man’s shed took the internet by storm. Was this a house-proud mouse, or was it the animal's way of making sense of a frenetic environment? An emerging field of scientists focusing on animal behaviour and emotions help us shed some light on such questions. Along the way we meet a dog training specialist, learn what a sniffari is, go for playtime with a thumb-sucking otter, and visit an OCD clinic. We’ll also be getting tips on how to give your pets the best home environment, and meet an animal enrichment officer in South Africa, who knows how to spot the signs of an unhelpful habit developing. Contributors: Karolina Westlund, Ethologist, Stockholm University and ILLIS Ben Terry, CBT Therapist, Priory Hospital North London Karin Pienaar, Animal Behaviourist, COAPE International Candice Ward, Animal Behaviourist, Johannesburg ZooJaak Panksepp clip: The science of emotions: Jaak Panksepp at TEDxRainier Producer: Robbie Wojciechowski Presenter: Alex Lathbridge Editor: Cathy Edwards Production co-ordinator: Connor Morgans Additional recording by Elna Schutz(Photo: Portrait of border collie puppy biting a curtain. Credit: Rawlstock/Getty Images)

Crowd Science listener Maik wants to know what the BMI is and what his BMI score says about his body. He trains dogs for a living and wonders if, like different breeds of dog, we simply have different body types? Marnie Chesterton comes up with some answers, talking to doctors about how the BMI is used and misused in clinical practice, and looks at some alternative methods for measuring our body composition. She also sits down with philosopher Kate Manne to discuss the realities of living in a fat-phobic world. We hear from Tonga in the South Pacific, where high BMI scores have labelled the country highly obese. But this is not necessarily how Tongans see themselves. And Marnie finds out if the BMI will continue to be used across the world as an important health marker or whether it is destined for the scrap heap of medical history. Contributors: Professor Kate Manne Dr Francesco Rubino Dr Naveed Sattar Professor Brendon Noble Technician Leah Siegel Fononga Pulu Sela Latailakepa Presenter: Marnie Chesterton Producer: Richard Walker Editor: Cathy Edwards Production co-ordinator: Connor Morgans Studio manager: Emma Harth

CrowdScience listener Gregory wants to know what affects the way we see the colours of the world. He was looking at a blue summer sky with a friend and they got to wondering whether they both see the same colour blue. So what does influence our vision of the colours that surround us? Could eye colour have anything to do with it? And can we ever really know if your blue sky is the same as mine?Caroline Steel comes up with some answers, talking to colour scientists about their research into the multiple factors that enable us to see in multi colours, from the intricate biology of our eye to the changing environment around us.She also investigates her own colour vision and solves a personal mystery, discovering why the world has always looked a slightly different colour from each eye.Contributors: Professor Jay Neitz, Department of Opthalmology, University of Washington, US Professor Hannah Smithson, Department of Experimental Psychology, University of Oxford Dr Juan Perea García, researcher, Department of Cognitive Psychology, University of Leiden Dr Lauren Welbourne, researcher, Department of Psychology, University of York Dr Adam Bibbey, lecturer in sport, Department of Sport, Oxford Brookes University Presenter: Caroline Steel Producer: Jo Glanville Editor: Cathy Edwards Production co-ordinator: Connor Morgans Studio manager: Jackie Margerum(Photo: LWA)

Storing your data in ‘the cloud’ might sound like an ethereal, intangible place, but it’s actually a physical location - a data centre. CrowdScience listener Art is worried about how much energy and water data centres are consuming. He’s from Ireland, where data centres are gobbling up almost 20% of the national electricity supply and that’s growing, fast.So how much energy and water are data centres using globally? And how can they become more sustainable? To answer Art’s question CrowdScience heads to chilly western Norway to visit a data centre hidden deep within a mountain, that’s said to be one of the most efficient in the world. And we hear how a data centre in South Africa is saving water and dealing with crippling power cuts by generating its own renewable energy.Do we just need to stream less TV and reduce our email inbox? With the help of carbon footprint expert Mike Berners-Lee, we crunch the numbers to find out.Featuring: Svein Atle Hagaseth, CEO of Green Mountain data centres in Norway Mike Berners-Lee, Professor at Lancaster University’s Environment Centre and consultant at Small World Consulting Thulani Ncube, Group Energy Lead at Africa Data CentresPresenter: Anand Jagatia Producer: Sophie Eastaugh Editor: Cathy Edwards Studio Manager: Donald MacDonald Production: Jonathan Harris & Connor Morgans Additional Recording by: Kobus van Niekerk

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. Kalina 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 reforestation 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

Noise 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 is a place where noise has become a way of life. But is that all about to change? Presenter: Alex Lathbridge Producer: Richard Walker 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 is a limit to the number of calories humans can burn and that engaging in physical activity is not always a sure-fire way to keep trim. So if working out is not 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. She is speaks to Prof Fatma Deniz from the Technical University of Berlin; Prof Naomi Baron from American University, Washington DC; Prof Patrick Nunn from the University of Sunshine Coast, Queensland and The Guesthouse Storytellers.Presenter: Anand Jagatia Producer: Jo Glanville Editor: Richard Collings Production co-ordinator: Jonathan Harrison Sound engineer: 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. 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 are one of the world’s most popular fish. And - in terms of the size of the industry - they’re also the world’s most valuable. They provide crucial proteins and fatty acids to many people’s diets. But like other species of fish, their production is undergoing a historic change. Plenty of salmon is still caught from the wild, but the majority is now farmed off the coasts of countries like Norway or Chile. With global demand on the rise, listener Jodie from Australia wants to know: which is healthier, farmed salmon or wild? CrowdScience’s Marnie Chesterton is on the case! Her first stop: a remote loch in the west of Scotland, where salmon company Mowi rears thousands of the fish in big, open-water nets. Marnie takes the chance to see for herself what salmon farming actually looks like. She then speaks to aquaculture nutritionist Stefanie Colombo, who researches the nutrient content of different types of salmon. Stefanie breaks down the health positives and negatives of each, as well as what causes some of these differences. Crucially, farmed salmon will vary in nutrition depending on where you are in the world. Jodie, the listener who asked this week’s question, is from Australia so her fish will most likely come from Tasmania. Chemist Christian Narkowicz has been conducting chemical tests on the salmon there - he tells Marnie what he’s found. When we ask which type of salmon is healthier, it’s also important to consider the issue of environmental health. Eilís Lawlor is an economist and the author of a report on externalities and unintended consequences of the global salmon industry. She and Marnie discuss problems of overfishing and environmental pollution. It’s also necessary to understand where wild salmon comes from. Marissa Wilson, director of the Alaska Marine Conservation Council, explains her average day out at sea and talks about some of the consequences of industrial offshore fishing. Finally, we ask if there’s a way to improve farmed salmon by moving it onto land? That’s Yonathan Zohar’s mission. In the basement of the Institute for Marine and Environmental Technology in Baltimore, USA, he keeps several tanks of salmon in artificial seawater, using bacteria to dispose of the waste. Is this where salmon farming is headed? Or is the future more complex? Presenter: Marnie Chesterton Producer: Phil Sansom Production Co-ordinator: Jonathan Harris Editor: Richard Collings (Photo: Atlantic Salmon jumping out of the water. Credit: Kevin Wells / Getty Images)

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, Senior Research Fellow at the Institute of Psychology, University of Pécs, HungaryPresenter: 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(Image: Frustrated father holds baby in his arms. Credit: Jamie Grill / Getty Images)

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 PrinceContributors: 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)