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<p>We take your questions about life, Earth and the universe to researchers hunting for answers at the frontiers of knowledge.</p>

BBC World Service

Where do shells come from? CrowdScience listener Tamsyn got in touch, a little embarrassed, confessing that she had managed to reach her twenties without realising that shells are made by living creatures.  Suddenly, her curiosity ran wild and she asked CrowdScience to investigate how these sea creatures have the architectural prowess to make shells in delicate ornamental shapes with beautiful colours and patterns. The job of sea-creature-investigator-in-chief falls to presenter Marnie Chesterton. She heads to the Natural History Museum in London, UK, where they have more shells than they can keep count of. Researcher Dr Suzanne Williams pulls out drawer after drawer of amazingly varied molluscs for Marnie to marvel at.  Then, it’s off to the beach to go shell hunting with Dr Leanne Melbourne, Senior Curator of Climate Change and the Dynamic Coast for Norfolk Museums in the UK. They look at the structure of shells, and Leanne explains how a soft mollusc is able to make a hard shell so sturdy they can survive for millions of years.  Marnie then gets into some mollusc maths. With shells strewn across a table, Professors Alain Goriely and Derek Moulton at the University of Oxford, UK show Marnie how they have mapped their shapes. Can Marnie uncover the formula that underpins the formation of shells, from the most basic to the inexplicably ornate? Presenter: Marnie Chesterton Producer: Tom Bonnett Editor: Ben Motley(Photo: Close up of young womans hands holding seashells, Eilat, Israel - stock photo Credit: PhotoStock-Israel via Getty Images)

How are shells made?

CrowdScience listener Gurmeet in India wants to know if plants can sense that we're around. She started wondering about this at a wellness centre where she was encouraged to hug a tree. She enjoyed the experience, but what about the tree? Did it enjoy being touched? And is there actually evidence that hugging a tree is good for us? Anand Jagatia talks to scientists about what happens to a plant when it's touched. Molecular biologist Olivier van Aken, from Lund University in Sweden, explains what happens inside a plant's cells – from mimosa whose leaves close up when touched to a Venus flytrap that sees a good opportunity for dinner. Plant biologist Alexander Jones, from the Sainsbury Laboratory at the University of Cambridge, UK, tells Anand how plants process information without a brain: when there's a threat from a hungry insect, it's their hormones that leap into action to defend it. Anand visits Wisley Garden in the UK and meets Ashby Lavelle Sachs, the Royal Horticultural Society's Wellbeing Fellow, who explains why being in nature is so good for our physical and psychological health. And he talks to South Korean researcher Sinae Park, from Konkuk University in Seoul, about the impact of touching plants with different types of foliage –  in an experiment, she found that it's the soft and smooth plants that made participants feel most relaxed. It turns out that plants find the whole experience of being touched pretty stressful. So next time you hug a tree, you might be getting a whole lot more pleasure out of it than the tree does.   Presenter Anand Jagatia Producer Jo Glanville Editor Ben Motley(Photo-  I love you nature! Nature and people - stock photo  Credit: Kieferpix via Getty Images)

Do plants know we're here?

CrowdScience listener Devin in Canada has just had a baby. Worried that all the good email addresses might be taken by the time his child needs one, he has already set up an account. But it got him wondering: how many email addresses belong to people who have died? From websites and blogs to email accounts, social media profiles, gaming avatars and even our conversations with AI, we’re all leaving behind a trail of digital footprints that can outlive us. So what happens to them when we die? Are they deleted, recycled or preserved? And who gets to decide? Presenter Anand Jagatia travels beyond the digital veil and into the internet’s afterlife to find out. Professor Edina Harbinja from the University of Birmingham Law School in the UK, an expert in ‘digital death’ and ‘post-mortem privacy’, explains how the law has struggled to keep pace with our digital lives. While it’s relatively straightforward to decide who inherits physical letters and photographs, what happens when those memories are stored in emails or on social media? For artist Janilda Bartolemeu, encountering messages from her father on Facebook long after his death was like interacting with a ghost. Anand visits her artwork at IMPAKT gallery in Utrecht, Netherlands, part of the exhibition Data Never Dies, where curator Rosa Webers explores how art can help us understand the human impact of technology. Finally, sociologist Professor Carl Öhman of Uppsala University in Sweden reveals that the number of dead people online will outnumber the living sooner than we might think. It raises profound questions about how we understand the internet, and ourselves within it. Presenter: Anand Jagatia Producer: Emily Knight Editor: Ben Motley(Photo:  Grave on laptop computer, 3d render - stock photo Credit: Brankospejs via Getty Images)

How many dead people are on the internet?

CrowdScience listener Lisa, who is from South Africa but now lives in the UK, has been a vegetarian for many years. Sometimes though, she still finds herself craving meats – like spaghetti bolognese or a burger. To satisfy these cravings, she eats ‘alt-meats’, products meant to look and taste like meat but made from vegetables.  This has her wondering though, are these alternative meats better for the planet than actual meat would be? And what about her health? Given that many of these foods are highly processed, would eating meat be better for her?  Presenter Chhavi Sachdev speaks to food systems researcher Charlotte Bunge from Uppsala University on Sweden, US health journalist Alice Callahan and researcher Christopher Gardner from Stanford University in the US to try and pick apart the positives and negatives of replacing ‘real’ meat with ‘pretend’ meat, before visiting an Indian company producing meat that was grown in a lab. Presenter: Chhavi Sachdev Producer: Margaret Sessa-Hawkins Editor: Ben Motley(Photo:Raw frankfurter sausage on a fork isolated - stock photo Credit:Andrey Sayfutdinov via Getty Images)

Can my veggie sausages save the world?

Your heart pounds, your chest tightens, your stomach drops and your legs feel weak and shaky. Your palms are sweating and a tingling rush spreads through your arms and fingertips as your brain is overwhelmed with feelings of tension and fear. And yet, you’ve asked for this. You wanted to be on this ride, at this theme park, hurtling towards the ground at a frightening speed. But why? An adrenaline rush is the body’s fight-or-flight response to intense fear, stress or excitement. It sends signals from the brain to the body, releasing hormones and redirecting the flow of blood around our veins. It’s designed to help us survive dangerous situations – so why would we deliberately want to put ourselves into those situations, just to feel the rush? That’s the question from CrowdScience listener Gunnar, aged 11, in Washington State USA. He wants to know why we try and seek an adrenaline rush by doing wild and crazy things, and CrowdScience’s wild and crazy Alex Lathbridge is on the case. Andy Hine, from the Rollercoaster Club of Great Britain, gives us a potted global history of the rollercoaster, revealing that it all started with Russian ice. Inevitably it’s not long before we start discussing ‘G-force’, so Canadian astronaut Dr Shawna Pandya explains what that means, and how it affects you when a rollercoaster is hurtling downwards or looping the loop. But what’s going on in our bodies and brains when we experience these forces? Brendan Walker is Professor of Creative Industries at Middlesex University in the UK. He tells Alex that a rollercoaster is a giant industrial machine which has been engineered to process humans, a little bit like tins in a factory, to deliver an ingredient. That ingredient is thrill – so how do they do it? Alex takes a ride on ‘Rage’ at Adventure Island in Southend on Sea in the UK to find out. Brendan claims that this ride is, scientifically speaking, the most thrilling rollercoaster in the country. Even Adventure Island owner Philip Miller declines to join Alex for a ride, but will it help Alex understand why Gunnar likes them so much? Presenter: Alex Lathbridge Producers: Harrison Lewis and Emily Knight Editor: Ben Motley(Photo: Spiraling Roller Coaster - stock photo- Credit: Alan Schein Photography via Getty Images)

Why do I love rollercoasters?

Some fish can deliver electric shocks with four times the voltage of the electricity in your plug sockets at home . Crowdscience listener Mouhammed in Cameroon was stunned by this, so he charged us with finding out how they do it. Presenter Caroline Steel heads to Bayreuth in Germany to meet some eels who have this amazing ability. Dr Stefan Schuster and Susanne Proschke introduce us to their collection of electric fish, and help us conduct some experiments to work out how the fish are wired. We’ll be diving into electric fishes' anatomy, learning how a specialised organ allows them to generate massive voltages of electricity. Harold Zakon from the University of Texas will help us understand their evolutionary history, while Brazilian ecologist Nonato Junior takes us on a journey into the currents of the Amazon River where electric eels live. And we’ll answer a question that has boggled philosophers, thinkers, and scientists for over 2000 years. If these fish can stun a human, a crocodile or even a horse, how do they survive the electric shocks themselves? (Photo: Blue lightning bolt streaks. Credit: Ludmila Snimshikova/Getty Images. Electric Eel, Venezuela. Credit: Reinhard Dirscherl/Getty Images)Presenter: Caroline Steel 
Producer: Robbie Wojciechowski 
Editor: Ben Motley

How do electric fish make electricity?

CrowdScience listener Matt wants to know why he's warm blooded. He started thinking about this when he was watching some ants during the recent heatwave in Europe and wondered why their blood didn't boil. What are the pros and cons of being warm-blooded like us or cold-blooded reptiles like lizards? Caroline Steel meets evolutionary biologist Dr Manuel Leal from the University of Missouri in the US, who explains the differences between ectotherms (cold-blooded animals) and endotherms (warm-blooded animals). She discovers that the terms cold blooded and warm blooded are actually misleading, because reptiles can reach a high body temperature and some might even become warmer than us. She talks to Simon Hodder, Professor of Environmental Ergonomics at Loughborough University in the UK, who describes how our bodies regulate heat, how we cool down when we get too warm and how that's all controlled by our brains.  Caroline also gets to meet some hedgehogs in the wild with Julia Nowack, an ecophysiologist from Liverpool John Moores University, who researches thermoregulation and is monitoring hedgehogs when they hibernate. Changing body temperature is one of the ways that some endotherms survive the winter when it's colder and there's less food around.  So who has the advantage? The warm-blooded endotherms who can heat their own bodies or the cold-blooded ectotherms who rely on the sun? Reptiles can get away with eating very occasionally while mammals and birds have to keep fuelling their energy with food to keep the heat going. That means we can live in most climates and have a better chance of escaping predators, but is it really best? Presenter: Caroline Steel Producer: Jo Glanville Editor: Ben Motley (Photo: European hedgehog (Erinaceus europaeus) adult animal in a snow covered garden in winter, England, United Kingdom - stock photo Credit:	imageBROKER/Kevin Sawford via Getty Images)

Why am I warm blooded?

Why is it hard to concentrate, and why does it feel like such hard work? The CrowdScience inbox is full of questions like that, so for this show we’re concentrating on concentration and focusing on how we focus. We’ll be answering questions about the extra energy the brain uses when we’re concentrating, whether mental effort can tire you out more than physical effort, why we zone out when faced with a difficult task and how the ability to multitask is governed by our overall cognitive load. To find the answers, presenter Alex Lathbridge is paying attention to a team of experts. Psychology professor Sophie Leroy from the University of Washington in the USA studies the impact of being interrupted on our ability to perform, cognitive neuroscientist Professor Salvador Soto-Faraco from the Universitat Pompeu Fabra in Barcelona, Spain researches how sight, sound and touch are blended together by the brain, and psychology professor Polly Dalton runs the Attention Lab at Royal Holloway University in London, UK. We’ll be trying to distract them with gossip about what we had for lunch, finding out why the brain is like a bike and, most importantly, discovering how you can concentrate better on shows exactly like this one. Presenter: Alex Lathbridge Producer: Tom Bonnett Editor: Ben Motley(Photo: Woman with glasses thinking and pointing upward- stock photo - Credit:  ismagilov via Getty Images)

Why can't I concentrate?

Tuberculosis kills more than a million people every year. It’s the world’s leading cause of death from a single infectious agent. This is despite the fact that we've had a cure for TB since the 1940s and a vaccine that’s over 100 years old. So why is TB still causing so many people to die?  That’s what CrowdScience listener John in Tanzania wants to know, and presenter Marnie Chesterton is on the case. Over in Paris, she’s joined by Dr Claas Kirchhelle, historian of science, medicine and technology at French National Institute of Health and Medical Research (INSERM)  to look into the history and efficacy of the vaccine, known as BCG. As Dr Maximiliano Gutierrez, Associate Research Director at the Francis Crick Institute adds, the BCG is both effective and ineffective, protecting children well against severe TB, but offering inconsistent and often poor protection in adults. He also explains that antibiotics are a trickier treatment than we might expect. Over in Kenya’s Kibera slums, Janet tells us her about her experience of the drugs first hand.  Dr Dany Beste, Senior Lecturer In Microbial Metabolism, University of Surrey, has been described as a dietician of mycobacterium tuberculosis. She explains the limitations of our knowledge of this bacterium, and why it is proving such a tricky customer. And since a better vaccine is the main hope for reducing the TB burden, Professor Angelique Luabeya Kany Kany, Chief Research Officer at University of Cape Town, shares her hopes for the first new alternative vaccine in 100 years: m72. Large phase 3 clinical trials are currently underway, and, if successful, could prevent millions of cases, and deaths a year. Presenter: Marnie ChestertonProducer: Marnie ChestertonEditor: Ben Motley (Photo: Doctor with vial of the doses vaccine for BCG Bacillus Calmette Guerin against tuberculosis disease. Medicine and health care concept - stock photo - Credit: angelp via Getty Images)

Why is TB still killing people?

Stare up at the night sky, and if you’re lucky, you might see a shooting star. Some people might make a wish, but CrowdScience listener Scott in California in the USA, thinks differently. He’s wondering how dangerous they might be. Shooting stars are actually meteors, ending their incredible journey whizzing through the depths of space by burning through our atmosphere, and crashing down to earth. And Scott’s not wrong to worry about them! In May 2026, an enormous meteor exploded off the coast of Massachusetts, causing a loud sonic boom before crashing into the ocean, releasing the equivalent energy of 300 tons of TNT! So, should we be worried? Marnie Chesterton is on the case. In Australia, Hadrien Devillepoix is the chief scientist for the Desert Fireball Network, which tracks meteors through the sky, and tries to recover any meteorites which make it to earth. He explains just how many of these smaller space rocks arrive on our planet every day, how many of them survive long enough to make it to the surface, and tries to figure out how much should we be worried about it happening to us. Over in the USA, NASA are less worried about the meteors, and more concerned about their big brothers – asteroids. These are the ones which could take out your whole neighbourhood. Or your whole city. Or even the whole planet. Kelly Fast, with NASA's Planetary Defense Coordination Office explains what the chances are one might be headed our way, and what we could do about it if they are. Push them away, pull them off course, or blow them up, are the options on the table. But space rocks, small OR large, aren’t the only things which could be tumbling down on our heads from outside our atmosphere. In fact, you might be more likely to be hit but something of our own – a man-made piece of space junk, falling out of orbit and whizzing towards the surface. Stephen Wokes, chief engineer at Astroscale, explains their mission: to use their innovative satellite to clean up Low Earth Orbit, and reduce the risk to us here on the ground. PRESENTER: Marnie Chesterton PRODUCER: Emily Knight PRODUCTION COORDINATOR: Stuart Laws EDITOR: Ben Motley (photo: Meteor Impact On Earth - Fired Asteroid In Collision With Planet - Contain 3d Rendering - elements of this image furnished by NASA - stock photo- Credit: RomoloTavani via Getty Images)

Will I get hit by a meteor?

We’re delving into the CrowdScience archive to give you another chance to hear an award-winning show from 2025. CrowdScience listener Dorit has a problem. She wants the tiles in her new bathroom to be arranged randomly but, no matter what she does, it still looks like they form some kind of pattern. This has got Dorit thinking about randomness – what is it, how do you create it, why do we find it so hard to recognise, and is anything really random at all? And if nothing is truly random, does it mean that everything is theoretically predictable? Tiling your bathroom is a much more existential problem than you might have thought. Never afraid of a question, whether big (is everything pre-determined?) or small (how do I tile my bathroom?), CrowdScience is on the case. Anand Jagatia heads to Switzerland to meet Hugo Duminil-Copin, a mathematician at the University of Geneva who specialises in probability theory. On the top floor of an old bank, Hugo has Anand flipping an imaginary coin in a random order. Hugo explains that randomness is something that cannot be predicted by any means – so why is it so easy for Hugo to guess what Anand’s next move is? Meanwhile, at the National Institutes of Mental Health in Maryland USA, Susan Wardle is a cognitive neuroscientist who researches how the human brain processes visual information. Can neuroscience help Dorit with her tiling problem, and is there a reason why the human brain likes to put random objects into some kind of order? Geneva is also the birthplace of the first Quantum Random Number Generator for smartphones, and CrowdScience has persuaded some of the University of Geneva’s finest quantum physicists to hook a photon detector up to a synthesiser. Thanks to Tiff Brydges and Nicolas Brunner, we can actually hear quantum particles behaving randomly. But is quantum randomness truly random, or just a pattern that we can’t see? And could quantum physics help Dorit tile her bathroom? Presenter: Anand Jagatia Producer: Ben Motley Editor: Cathy Edwards(Photo: Many wooden dice - stock photo- Credit: 	akiyoko via Getty Images)

Is anything truly random?

Space missions are searching for evidence of extra-terrestrial life. CrowdScience listener George in Kenya wants to know what could be up there, and if there’s a risk it could harm humanity. With rovers currently analysing samples on Mars, missions searching for the building blocks of life on Jupiter’s icy moons, George’s concern that there could be diseases in space is timely. Presenter Anand Jagatia sets out to try and find an answer while keeping his feet on the Earth. He meets astrobiologist Dr Michaela Musilova, who runs experiments to try and understand what kinds of microbes could survive on other planets. In her work at NASA’s Jet Propulsion Laboratory, she recreates Mars-like environments that test lifeforms’ resilience to the rigours of the Red Planet. And if there are harmful pathogens in space, how do we make sure these missions don't bring them back to Earth? Anand talks to ‘planetary protection officer’ Silvio Sinibaldi from the European Space Agency, who explains what experts are doing to protect us. He helps Anand get suited and booted in specialist clothing so they can enter a highly sterile environment called a ‘clean room’, where things being sent to space are built. He also meets Paul Meacham, former chief engineer on the Rosalind Franklin Rover. The rover is being sent to Mars to try to determine whether life ever existed there, and even whether it still does. Paul shows us around the Airbus Defence and Space site where his team built the rover and explains high-tech measures to avoid contamination. And what would a programme on space be without an astronaut? Anand meets Kate Rubins, who spent 300 days on the International Space Station. While she was there, she ran experiments investigating what happens to microbes in space. It turns out that microbes affect humans differently in orbit to how they affect us on Earth.  Presenter: Anand Jagatia Producer: Tom Bonnett  Editor: Ben Motley(Photo : 3D render of the Coronavirus Covid-19 floating in the air with astronaut wearing space suit. - stock photo- Credit: Artur Debat via Getty Images)

Are there diseases in space?

CrowdScience listener Liana from Canada got in touch to ask about some very specific rocks she’d seen on an island in Indonesia – jagged, rugged and a very strange shape: hexagonal. They were in long columns, and clicked together like a jigsaw. But what are they, and how did they get there? Across the world in the UK, CrowdScience listener Sarah emailed us to ask about the famous rocks of the Giant’s Causeway in Northern Ireland. What makes them so uniformly hexagonal? Presenter Alex Lathbridge investigates, visiting the Giant’s Causeway to speak to geologist Dr Kirstin Lemon from the Geological Survey of Northern Ireland. She explains how this amazing landscape formed, and why the mythical rocks look the way they do today. We also hear from Dr Alfend Rudyawan from Institut Teknologi Bandung in Indonesia about Liana’s intriguing rocks. Are these distant locations more closely related than you might think? And we look to nature – because angular, uniform hexagons crop up surprisingly often. Professor Jean-Marc Schlenker from the University of Luxembourg explains why hexagons are much better than other shapes.  Presenter: Alex Lathbridge  Producer: Hannah Fisher Editor: Ben Motley(photo:  Giant`s Causeway in Northern Ireland Stock photo- Credit: 	MANUEL FIL ORDIERES GARCIA  via Getty Images)

What are these strange rocks?

Many plants need pollen from another plant of the same species in order to reproduce, but they don’t have legs so they can’t simply walk around looking for a mate. As a result, many of them rely on animals to transfer pollen from one plant to another. They’ve developed a hugely diverse range of techniques to attract them, including their appearance, taste and smell. CrowdScience listener Alice in the UK wants to know how they have evolved to do this. To try and answer the question, presenter Anand Jagatia goes trekking up a mountain in the Philippines, battling mud and leeches in the hunt for an incredibly rare flower. Rafflesia has evolved to look and smell like rotting meat in order to attract flies, so it’s the perfect example of a plant that goes to fascinating extremes to make sure it gets pollinated.  It only blooms for a few days each year, so to find it Anand is going to need the help of scientists at the University of the Philippines Los Baños and Lewis Barrett, Senior Botanical Propagator at the University of Oxford Botanic Garden and Arboretum. Anand also visits the University of the Philippines Laguna Quezon Land Grant, a huge site containing more than 5,500 hectares of protected forest land. Professor Pastor Malabrigo Jr shows him a fig tree that has a fascinatingly gruesome relationship with its pollinator wasps. So how did these amazingly diverse plants end up needing insect pollinators in the first place? Dr Kyra Krakos is a professor of biology at Maryville University and a research associate at the Missouri Botanical Garden in the United States. She explains to Anand that plants are surprisingly sexy – but how did they end up needing insects to survive? Back in the Philippines, Anand’s guides have never actually seen the Rafflesia flower themselves, despite many attempts. So could this be the time they finally get lucky? Presenter: Anand Jagatia Producer: Dan Welsh Editor: Ben Motley With special thanks to Dr Chris Thorogood, Associate Professor of Biology at the University of Oxford and founder of the Community for the Conservation & Research of Rafflesia(photo: Edited high angle view of Rafflesia on green gradient - Stock photo- Credit: Mohamed Tazi Cherti / 500px via Getty Images)

How did plants evolve to attract insects?

“What separates humans from animals, is an interest in the past”. That’s a 900-year-old quote from a textbook that Nigerian listener Taiwo came across, and he wrote to CrowdScience to ask if modern science would agree. Most of us spend time thinking about the past, whether it is nostalgia for a bygone age or just wondering where we put the house keys yesterday. But is that just a human activity or do other animals also ruminate on their history and use it to make decisions? Taiwo wants to know if there is any evidence to show that animals have an interest in the past and if it matters to them. Presenter Caroline Steel has a history of answering questions like this, so she sets out to find an answer. She meets researchers who have found evidence that animals not only remember past events, but use their memory for planning. She talks to neuroscientist Dr Freyja Olafsdottir and discovers that some animals, including rats and mice, have the same brain structure for memory as humans.  She meets baby magpies in Professor Nicola Clayton’s laboratory in the UK and finds out about some of the very smart tactics jays use to hide their food from rivals, evidence that they’re using their memory to protect their interests. She talks to psychologist Dr Gema Martin-Ordas whose research has shown that chimpanzees not only remember past events, but use what they’ve learnt in the future.  And she tests the memory of her own cat Oli, wondering if his ability to remember dinner time suggests that he is interested in the past too. Ultimately it comes down to questions of consciousness, so as Caroline grapples with the idea that we can’t even be certain that other humans are genuinely conscious, what hope do we have of finding an answer for Taiwo? Presenter: Caroline Steel Producer: Jo Glanville Editor: Ben Motley(Photo: Cute clever cat with glasses reading a book. The cat lies on a stack of old books on a blue background. Credit:vvvita/Getty Images)

Do animals care about the past?

CrowdScience listener Rachel uses Bluetooth headphones on her cycle to work, seamlessly playing music from her phone without using wires. But how does this technology send information through the air? To find out, Rachel and presenter Caroline Steel travel to Cambridge in the UK to meet telecommunications expert William Webb. He explains what Bluetooth signals actually are – and demonstrates why their properties are linked to the invention of leaky microwave ovens. Caroline speaks to Jaap Haartsen, the inventor of Bluetooth, who reveals the hidden meaning of its logo, and what the name has to do with an ancient Viking king. And she learns how a new flavour of “low energy” Bluetooth is having an unexpected application: helping ecologists like Damien Farine understand animal behaviour. Which leads her to an old tobacco barn in Switzerland, to meet researcher Bettina Almasi and her team – along with some very cute baby barn owls.  Presenter: Caroline Steel Producer: Anand Jagatia Editors: Ben Motley & Ilan Goodman(Photo:Composite photo collage of hands hold phone device internet antenna connection technology bluetooth - stock photo- Credit: Deagreez via Getty Images)

How does Bluetooth work?

CrowdScience listener Haruka has been making origami cranes out of paper since she was a child. Creating one out of a cloth napkin, however, was a next-level challenge. It gave her a new appreciation of paper’s excellent foldability, and made her wonder: what is it about paper’s structure that means it remembers its creases? 
 
We set out to unfold her question as we peer into paper’s secrets. First stop: Frogmore, the world’s first mechanised paper mill. Here, Dr Steven Mann is on hand to explain the papermaking process, the chemistry of paper, and why that makes for a foldable sheet. Host Caroline Steel tries to make a paper crane, assisted by both listener Haruka and origami teacher Toshiko Kurata, who also introduces us to an array of paper types. Each type folds differently, and, with the help of a trusty microscope, Professor Bill Sampson from the University of Manchester reveals why. Finally, we see just how complex paper folding can get, meeting Professor Tomohiro Tachi from the University of Tokyo, and his invention, The Origamizer. 
 
Presenter: Caroline Steel Producer: Cathy Edwards Editor: Ben Motley(Photo: Toshiko Kurata and Caroline Steel with origami creations - Credit:BBC)

Why does paper fold so well?

CrowdScience listener George is showing Alex Lathbridge around a small, dark, and extremely hot shed, just outside the city of Accra in Ghana. Inside are row after row of shelves, stacked high with bulging grow-bags. And out of some of them, gorgeous cascades of oyster mushrooms are bursting into bloom. We’re on George’s mushroom farm, and he’s noticed something interesting. Even though the conditions in his grow-shed are tightly controlled – they have exactly the same food, water, and light as each other – nevertheless, they respond differently. Some are more vigorous than others, some bloom quicker, others last longer, and some are more tolerant when the conditions change. And this got George wondering. Could ‘brainless’ lifeforms like mushrooms, and plants, have different ‘personalities’? Do they experience the world differently, and live their lives differently from each other? Alex Lathbridge is on the case.  He visits the PGRRI, the Plant Genetic Resources Research Centre, for a quick lesson on genetic variation in the plant world. Plants are all different at the genetic level, and it’s those differences which can result in a tastier fruit, or a hardier crop. But would we call traits like these personality?  In the Minimal Intelligence Lab in the University of Murcia in Spain, Paco Calvo thinks that we absolutely should. He studies plant intelligence, and points Alex to a whole host of examples of plants being smart in ways which might surprise you. Each one is an individual, and if we can only slow down enough to appreciate them properly, we’d be able to understand them better too. Back in Ghana, Alex meets plant physiologist Dr Acheampong Atta-Boateng, in the beautiful grounds of Aburi Botanical Gardens, to meet some of these plants for himself. And he discovers that there’s a whole world of smart, resilient, and resourceful little organisms in the plant world, full of personality, if you know where to look. Who needs a brain!? Presenter: Alex Lathbridge Producer: Emily Knight Editor: Ben Motley(Photo: Drawing of a face and smiling eyes on a sunflower flower - stock photo- Credit: Jose A. Bernat Bacete via Getty Images)

Do plants have personalities?

Why is there such a variety of tongues in the animal kingdom? CrowdScience listener Dale has observed that his dog’s tongue is different from his and so is his cat’s.  He’d like to know the reason. Caroline Steel visits London Zoo in the UK to find out more about the different types of tongues - from giraffes and birds to lizards. She talks to evolutionary biologist Kurt Schwenk, who explains that the development of tongues made it possible for animals to make the leap from the sea to life on land. Fish could rely on water to help them swallow food, but air and gravity required a whole different mechanism for having dinner. But why is there such a variety of tongues between species - from the forked tongue of a snake to the rough tongue of a cat? And does it all come down to our diets? Researcher Callum Ross reveals how he’s pioneered a new technique for investigating how animals use their tongues when they eat and drink, and why tongues are so important for swallowing. Presenter: Caroline Steel Producer: Jo Glanville Editor: Ben Motley (Photo: Giraffe licking its lips - stock photo - Credit: laurenepbath via Getty Images)

What's the deal with tongues?

CrowdScience listener Daniel in Accra, Ghana is an introvert. Or at least, he thinks he is. And he’s worried that his preference for quiet spaces and lower social interaction might be holding him back in life. But what is introversion really? How do introverts and extroverts see the world differently? And is it better to be one or the other?  Presenter Alex Lathbridge spends his working days talking to interesting people like Daniel. He loves meeting people, and talking to them too, yet he also thinks that deep down, he might be an introvert. To understand how and why people come to be introverted or extraverted, and what’s happening in the brain, he pays a visit to neuroscientist Dr Thomas Tagoe from the University of Ghana Medical school, for a peek inside the mind. Turns out, introverts aren’t shy, and definitely aren’t anti-social either, despite what people might assume. The difference is more about how we process stimulation, and at what point we find it all a bit too much to process. Although sometimes it might feel like the world is built for the extraverts out there, Thomas offers some reassurance. There are huge benefits to being introverted too, and there’s room in the world for all the different personality types to thrive. But how about in the workplace? Daniel is worried that his introversion could be holding him back at work. He feels like being good at your job is not always enough – you need to be able to network, charm people, and “work the room” if you want to succeed. So, Alex heads for the Methodist University of Ghana to meet Professor William Baah-Boateng, who has studied the effect of all the different personality types on their performance in the workplace. Is there a place for the introverts of this work to make their mark? Presenter: Alex Lathbridge Producer: Emily Knight Editor: Ben Motley  (Photo:A view of a woman's eye looking through a hole in some colorful paper-Stock Photo - Credit:PeopleImages via Getty Images)

Why am I an introvert?

Why do we feel itchy? So many listeners have emailed in with questions about itchiness, and presenter Anand Jagatia on the case.  We explore why we itch, the different types of itch, the different causes, and why scratching can help with the itchy sensation.  Anand puts your questions to an expert panel: Dr Sonja Ständer, professor of Dermatology and Neurodermatology at the University of Münster and and Gil Yosipovitch, Professor of Dermatology at the Miller School of Medicine at University of Miami.  Also joining them from the University of Hull in the UK is Dr Henning Holle who studies the psychology of itch. He’s got an itchy game for Anand, Sonja and Gil to play in the studio, but is it really as simple as he’s letting on? Presenter: Anand Jagatia  Producer: Tom Bonnett  Editor: Ben Motley  (Photo: Young women have skin problems, irritation on her skin, skin infection itching red rash, arm scratching with hands, isolated over yellow background - stock photo - Credit: Arnav Pratap Singh via Getty Images)

Why do we itch?

As our oceans warm due to climate change, sea levels are rising. It ought to be straightforward – as water gets warmer, it increases in volume. All the world’s oceans are connected, so how come sea levels are rising at different rates around the world, and even falling in some places? CrowdScience listener Alison in Australia wants to know the science behind the mystery.  Presenter Anand Jagatia travels to the Philippines to investigate. The country is being particularly affected by the issue, with its more than 7,500 islands experiencing sea level rises that are double the global average. On Palawan Island, in the east of the country, he speaks to people whose homes and livelihoods are being put at risk by rising waters. He also visits the Philippine Coast Guard in Manila and speaks to Commander James Barandino, from their Marine Environmental Protection division, to hear how their work is being affected by sea level rises and the flooding it causes. Dr Charina Lyn Repollo from the University of the Philippines Marine Science Institute shows Anand how they monitor sea levels at dozens of locations. Their data shows huge variations in sea level across the country. How can that be the case? Anand also speaks to Jonathan Bamber, Professor of Earth Observation and Glaciology at the University of Bristol in the UK, to unpick the science behind how sea levels can rise at different rates in different places. And how do we protect people from rising waters? Dr Rodel Diaz Lasco from the Oscar M. Lopez Center for Climate Change Adaptation and Disaster Risk Management in Manila, explains how global collaboration might hold the key. Presenter: Anand Jagatia Producer: Dan Welsh Editor: Ben Motley (Photo: Globe floating on water - stock photo- Credit: Jan Hakan Dahlstrom via Getty Images)

How come sea levels are rising faster in some places than others?

CrowdScience listener Jeroen finds it hard to remember people's faces - and he wants to know why. He wonders if it's to do with getting older and if there’s any way of improving. Presenter Caroline Steel has the same problem and is keen to find an answer too. She meets Professor Zaira Cattaneo, a neuroscientist based in Italy who researches face perception. Zaira has discovered which parts of the brain are engaged in facial recognition. She explains how we recognise faces and why ageing could be a factor in Jeroen’s difficulty. Caroline travels to Bournemouth in the UK to meet researcher Professor Sarah Bate, who assesses Caroline's ability to recognise faces and explains the causes of face blindness. And she compares notes with fellow CrowdScience presenter Marnie Chesterton, who also has difficulty remembering faces. Around two per cent of the population have the condition. Could there be a reason why more than a third of CrowdScience presenters experience face blindness? If you’ve got a science question you’d like us to answer, email crowdscience@bbc.co.uk. Presenter Caroline Steel Producer Jo Glanville Editor Ben Motley(Photo:Packaging cardboard on the head with different emotions - stock photo Credit: Flying broccoli via Getty Images)

Why can't I recognise faces?

CrowdScience listeners Dougie and Molly have been wondering what happens to animals when they die, and whether there are animals that hold rituals to mark the passing of one of their kin. Presenter Caroline Steel is on the case, trying to work out what happens to the bodies of animals when they die. Dougie and Molly say they rarely see animal carcasses where they live - so where do they all go? Dr Sarah Perkins of Cardiff University in the UK runs a research project called Roadlab, which logs how quickly the bodies of animals killed by traffic disappear, and she thinks she might have a clue. Caroline joins her on a hunt through the undergrowth for animals, and answers. And when animals lose a member of their flock, herd or school, do they indulge in rituals that look anything like a funeral? Caroline meets Dr Kaeli Swift, an ecologist at the University of Washington in the US, who has some surprising evidence from her research into bereaved crows. Meanhile, in Botswana, Mathale ‘Metal’ Mosheti is a safari guide in Chobe National Park. The African Savannah Elephants there demonstrate some remarkable behaviour when another elephant dies. But do animals really grieve for their loved ones? Dr Barbara J. King, Emerita Professor of Anthropology at William & Mary University in the US, has some ideas.  But is it enough to answer Dougie and Molly’s question? Presenter: Caroline Steel Producer: Tom Bonnett Editor: Ben Motley(Photo: Little red sick bird canary inside a wheelbarrow pushed by a lizard. Credit: Fernando Trabanco/Getty Images)

Do animals hold funerals?

Salt can be found in almost every kitchen in the world. But how did this seemingly simple ingredient become the world's favourite flavour enhancer? This week, Crowdscience sets out to uncover why these tiny crystals have such a powerful effect on us. We explore the magic behind this tiny mineral that has shaped our tongues, our culture, and our cravings. Our investigation begins with CrowdScience listener George, who heard from a friend that if he added a few grains of salt to his morning coffee, he could make it taste less bitter. Following some light investigation at his local coffee chain, he began wondering why salt make things taste more delicious. To try and find an answer, presenter Anand Jagatia heads to a salt mine in Austria with Daniel Bradner, an archaeologist from the Natural History Museum of Vienna. The mine is 200 kilometres from the sea, so where does all the salt come from? In London, UK, we meet Adriana Cavita, a chef who helps us explore how salt transforms what we eat:  sharpening aromas, softening harsh flavours, and boosting sweetness. We explore the receptors inside our mouth with taste expert Courtney Wilson from the University of Colorado School of Medicine in the US, to find out how we detect whether there’s too much or too little salt in our food.    And we meet Joel Geerling, Associate Professor of Neurology at the University of Iowa, US, who’s been looking inside the brain to try and work out why we crave salt. He’s discovered an incredible system that’s highly engineered to give us an appetite for salt. Could it be the answer to George’s question?  Presenter: Anand Jagatia Producer: Robbie Wojciechowski Editor: Ben Motley(Photo: Measuring Teaspoon of Sea Salt with Vibrant Colors - stock photo JannHuizenga via Getty Images)

Why does salt taste so good?

Is the world sitting on a ticking time bomb? CrowdScience listener Christel recently watched a documentary about a volcanic eruption in 536 AD that left her native Sweden under a cloud of ash for three years. It got her thinking, do we know when this could happen again?With more than 300 volcanoes – and 24 of them listed as currently active – the Philippines is a country where trying to predict eruptions has huge real world consequences.Presenter Anand Jagatia travels to Manila to meet the scientists at PHIVOLCS, the Philippine Institute of Volcanology and Seismology, including the head of their Volcano Monitoring and Eruption Prediction Division, Mariton Antonia Bornas, to find out how they try to predict volcanic activity in the country and help make sure communities are evacuated out of harm’s way.He travels with the team to Taal volcano, which experienced violent eruptions in 2020 and has been active again this year, to visit the observatory monitoring for signs of future activity and to hike to the main crater of the volcano with resident volcanologist Paolo Reniva.He also speaks to Dr George Cooper from Cardiff University in the UK about what makes a volcano a supervolcano, and to ask the all important question of if we know when this will happen again.Presenter: Anand JagatiaProducer: Dan WelshEditor: Ben Motley(Photo: Smoke Emitting From Volcanic Mountain Against Sky - stock photo -EyeEm Mobile GmbH via Getty Images)

When will the next super-volcano erupt?

Listener Bart in Australia sees invasive species in his area almost every day – rabbits, foxes, and cats. They were transplanted to Australia from Europe more than 100 years ago, but seem to be thriving in their new home.  This got him wondering: how are they going to evolve, now that they are in a new habitat? Can we predict what future evolution will look like based on what we already know?  To find out, Marnie Chesterton visits Sandy Ingelby at the Australian Museum, who manages the mammal collection. She shows Marnie how indigenous Australian animals have evolved to suit where they live.  On the island of Tasmania, Marnie meets the famous Tasmanian Devil and keeper Jono Thomas. Andy Flies from the University of Tasmania explains how the devil is evolving in real-time in response to a health crisis. So what might the invasive species in Bart’s backyard look like over the next 100 years? We’ll find out, with a little bit of help from palaeontologist Matt McCurry and millions of murderous toads. Presenter: Marnie Chesterton Producer:  Margaret Sessa-Hawkins Editor: Ben Motley(Photo: Wild rabbit- stock photo Credit: John Porter via Getty Images)

Will rabbits become super predators?

CrowdScience listener Po wants to know whether AI could one day replace all human jobs. And while he requests that CrowdScience continues to be hosted by people, it made presenters Caroline Steel and Anand Jagatia wonder – could an AI really present this show? To find out more about how AI models work and what they’re capable of, Caroline Steel speaks to AI journalist Alex Hern from The Economist. She creates an AI version of herself with Nicky Birch, Innovation Lead for the BBC’s generative AI program, and hears how the BBC is attempting to navigate the ethical use of this new technology.  Anand Jagatia speaks to phonetician Prof James Kirby about how synthetic AI voices have become so convincing, as well as why they still sound slightly unnatural. And Anand and Caroline ponder whether there could ever be a place for AI presenters on the airwaves.  Presenters: Caroline Steel and Anand Jagatia Producer: Anand Jagatia Additional production: Lorna Stewart Editor: Ben Motley(Photo: Mirror image of presenter Caroline holding microphone Credit: BBC)

Could AI present CrowdScience?

CrowdScience listener Doug has been experimenting with holding his wireless garage key to his chin. Why? Because he's testing a strange trick of physics.
 
The range of a key can apparently double when held against your head rather just being held in your hand. Could this really be true, and if so why?
 
Presenter Caroline Steel goes on a wavy journey of self-experimentation with antennas. She follows the story of Doug as he wanders the streets of Calgary in Alberta, Canada testing the key on his head from different distances and even testing it on his dog Maura’s head.
 
To understand the physics behind all this, Caroline meets Dr Lina Mohjazi, Lecturer of Autonomous Systems and Connectivity at the University of Glasgow and Guy Vandenbosch, Professor of Electromagnetic Radiation at KU Leuven University in Leuven, Belgium.
 
Presenter: Caroline Steel
Producer: Tom Bonnett
Editor: Ben Motley(Photo: Hand holding a car key remote in front of a red car - stock photo Credit: vadishzainer via Getty Images)

Can I unlock my car using my head?

CrowdScience listener Kassy in India wants to know if there’s any science to support the practice of ‘manifesting’ – the idea that you can make your wishes come true just by writing down your goals and sending your dreams out to the universe. Is it just a wacky belief or can it be backed up by research? Caroline Steel looks at the evidence to see if manifesting works. She talks to researcher Lucas Dixon in Australia, who has found that people who believe in manifesting are more likely to take risky financial decisions or end up bankrupt. She meets neuroscientist Sabina Brennan in Ireland who argues that psychology has already proven that our thoughts and beliefs shape our reality, through cognitive behavioural therapy for example. So there is evidence to show that some of the techniques in manifesting can work. Caroline also talks to psychologist Gabriele Oettingen in the US, whose research has demonstrated that just thinking about our wishes actually decreases our energy and makes it less likely that we’ll achieve our goals. She’s come up with her own method for increasing the likelihood of success.And Caroline tries out a manifesting technique for herself. Can it help her realise her dreams? Presenter: Caroline Steel
 
Producer: Jo Glanville Editor: Ben Motley(Photo: Enthusiastic brunette girl celebrating- stock photo Credit: Mix and Match Studio / 500px via Getty Images)

Can I really manifest the future?

CrowdScience listener Ndanusa in Ghana, is gazing up at the stars, and wondering. Big philosophical questions, like… what keeps our universe in balance? From our perspective here on earth, the universe seems like a vast, harmonious system, perpetuating eternally without change. But Ndanusa knows a thing or two about the stars, and he knows that they use up hydrogen as they burn, and release helium. And he’s wondering, is there something out there which does the opposite? Something that uses up helium, and produces hydrogen, to keep the universe in perfect, chemical equilibrium? His question makes sense! Here on earth for example, animals use up oxygen and produce carbon dioxide, and plants do the opposite. A perfect cycle of production and consumption which (at least in theory), keeps our planet in perfect balance. Could the same kind of system be in place in the wider expanse of the universe? His intriguing question leads presenter Alex Lathbridge on a journey into the blackness of deep space, the ancient origins of our universe, and the complex physics of the stars. He pops into the Ghana Radio Astronomy Observatory, just outside Accra, where astrophysicist Dr Proven Adzri helps him peer into the earliest few seconds of our universe, and find out what set the stars burning. And at Kwame Nkrumah University of Science and Technology, Dr Linus Labik talks him through what’s going on at the atomic level. And in the deep blackness of the night, up above the tree canopy of Kakum National Park, he takes a peek at the stars for himself. Local guides Chris and Kwabena explain how much meaning there is behind the stars in the night sky. Presenter: Alex Lathbridge Producer: Emily Knight Editor: Ben Motley  (Photo: Large orange and purple exploding orb - stock photo  Credit: 	Soubrette via Getty Images)

What keeps the universe in balance?

Australia’s Great Barrier Reef is one of the richest and most complex natural ecosystems on earth, and it’s home to over 600 species of coral – marine animals that are most closely related to jellyfish.  But the coral is under threat, with climate change, ocean acidification and marine heatwaves endangering the reef and the many iconic animals that depend on it. CrowdScience listener Felix, aged 9, wants to know what we’re doing to protect it, and presenter Caroline Steel is on the case. In this special edition of CrowdScience, we follow scientists from Australia’s Institute of Marine Science as they attempt to restore the reef with baby corals that they’ve nurtured in experimental tanks at their Sea Simulator facility on the country’s northeast coast. This experiment kicked off in December, as the researchers recreated the annual mass coral spawning event in controlled conditions, manipulating temperature, pH, light, and nutrients to breed coral baby that they can then use to reseed damaged sections of reef.  After loading up a lorry full of corals and waving it goodbye, Caroline heads north for a rendezvous at dawn, as the corals are loaded onto a boat in Cairns. She travels across the coral sea with marine biologists from AIMS, and is on hand as the corals are introduced to their new home in the ocean.  This is just the beginning - a proof of principle. In future years, the scientists are hoping to reseed heat-tolerant corals, and to scale up and automate this work. But even then, is the scale of the problem too big? Can we restore a reef area the size of Japan, or is it too late? Presenter: Caroline Steel Producer: Marnie Chesterton Editor: Ben Motley (Photo: Orange-lined triggerfish by coral in beautiful blue water - stock photo. Credit: treetstreet/Getty Images)

How can we save the Great Barrier Reef?

On a recent kayaking trip, CrowdScience listener Lanier sliced through his right thumb, putting it out of action for a while. This made life difficult, as he couldn’t button his shirt, tie his shoelaces or type efficiently on his smartphone. Missing the use of his thumb made him wonder: since opposable thumbs are so advantageous to those of us who have them, why didn’t they evolve in more species? Host Marnie Chesterton unpicks the evolution of our own unique thumbs with the help of paleoanthropologist Tracy Kivell, learning how our grip compares to that of other animals. We discover why mammals like horses and dogs have no use for thumbs, and why we humans don’t have opposable big toes. Meanwhile, at Taronga Zoo in Sydney, Australia, senior keepers Tarryn Williams Clow and Bec Russell-Cook introduce us to two different marsupials. Humphrey the koala has not one but two thumbs on each hand. Why did koalas develop this anatomical quirk when their closest living relative, the wombat, has spade-like digits? Dr Mark Eldridge from the Australian Museum shares his hypothesis. And what if we, too, had another thumb? Marnie tries on a robotic Third Thumb, built by designer Dani Clode. Dani has collaborated with neuroscientists from the Plasticity Lab at the University of Cambridge. She tells us what the Third Thumb has revealed about the human brain and how we control our digits. Presented by Marnie Chesterton Produced by Cathy Edwards and Margaret Sessa Hawkins for the BBC World Service(Photo: Kung-Fu Koala - stock photo Credit: Alex BOISSY / Getty Images)

Why don't more animals have opposable thumbs?

Noise cancelling headphones filter out sound waves that we don’t want to hear. Listener Ahmed in Libya loves wearing his and, as he was listening to them, he had a thought: ‘Could we cancel out light waves in a similar way to how noise cancelling headphones do it?’ He sent his question to CrowdScience and now presenter Alex Lathbridge is getting deep into the physics, to find out if light cancelling devices could replace curtains and shutters.  Alex starts at the Ray Dolby Centre in Cambridge in the UK, built to honour Ray Dolby’s invention of noise cancelling technology. In this amazing building he meets Jeremy Baumberg, Professor of Nanophotonics at Cambridge University. With the help of a tuning fork and a laser beams, Jeremy shows Alex that manipulating light is no easy feat. Undeterred, Alex tracks down Stefan Rotter, Professor of Theoretical Physics at Vienna Technical University in Austria. Stefan and his colleagues around the world have been pushing forward the development of a device called the ‘anti-laser’. Alex and Stefan explore whether this could be the light-cancelling device of Ahmed’s imagination.  And once we've created a light-cancelling device, what do we do with it? Mary Lou Jepsen is an inventor and the founder of health tech firm Openwater. She tells Alex about how she’s using light wave manipulation to open up new possibilities for medical imaging, and even treatment.   This programme includes clips from: 
 
Surrounded by Sound: Ray Dolby and the Art of Noise Reduction https://www.bbc.co.uk/programmes/m002bswq 
 
CrowdScience: Can we trap light in a box? https://www.bbc.co.uk/programmes/w3cswvwyPresenter: Alex Lathbridge Producer: Tom Bonnett Editor: Ben Motley(Photo: Eyesight and vision concept - stock photo  Credit: J Studios / Getty Images)

Can we cancel light waves?

CrowdScience listener Griffith in Ghana, isn’t JUST a CrowdScience listener. He’s also a listener to our sister show on the World Service, Unexpected Elements. But he’s noticed something funny. In the weekly Unexpected Elements multiple-choice quiz, the answer is almost NEVER ‘a’. It’s nearly always ‘b’, or ‘c’. Why is this? When we set the quiz, why are we so reluctant to choose option ‘a’? His question leads presenter Alex Lathbridge on a journey into the murky depths of our brain, where he discovers the cognitive biases which so often trip us up in games of chance, or probability. Your brain might be a marvellous machine when it comes to figuring out how to understand the world, but sometimes, in the name of efficiency, it takes clever little short-cuts to the answer.  This pragmatic approach to problem solving helps us manage an incredibly complicated world. But occasionally, especially when it comes to mathematics, chance, and probability, it leads us in the wrong direction. With the help of mathematician Kit Yates from the University of Bath in the UK, and some rather stale sweets, Alex will be finding out how to win at games of chance. Alex also explores the world of gaming, and gambling. Games of chance in which our intuition sometimes lets us down, and makes us choose unwisely. Rachel Croson, Professor of Economics at the University of Minnesota, USA, talks us through how the human brain can work against us. But can knowledge of those human pitfalls help us to win? Alex hears from Maria Konnikova, who turned her research on the psychology of poker into a successful gambling career. Can we really use maths to beat our brains, and learn how to win more often?   
Presenter Alex Lathbridge Producer Emily KnightEditor Ben Motley(Photo: Close up image of multiple choice question. Credit: BBC)

Do multiple choice questions make us biased?

CrowdScience listener Namrata and presenter Chhavi Sachdev have something in common. They both get more tanned in the summer in the United States than back home in India. Namrata wants to know why she came back from her run in Boston with such a deep tan and doesn’t have the same experience in India. She’s got quite a few theories herself and wonders if it’s to do with the angle of the sun, pollution or humidity. Chhavi talks to dermatologist Neelam Vashi, who’s based in Boston, to find out how we tan and what protects us from the sun.  She meets Julian Groebner at the World Radiation Centre in Switzerland who compares the data in India and the United States for CrowdScience and comes up with a surprising answer. She also talks to Indians in Mumbai who share their attitudes to tanning and what steps they take to protect themselves from the heat of the sun. Presenter Chhavi Sachdev Producer Jo Glanville Editor Ben Motley(Photo: Woman sunbathing on sun lounger by swimming pool. Credit: IndiaPix/Getty Images)

Why do I tan more in the US?

There’s something fishy going on in the Czech Republic, where CrowdScience listener Ian lives. He keeps tropical fish, and he’s noticed that when he adds new ones to his tank, they swim with others of the same breed. He wants to know how they recognise each other. Do they know what they look like, and recognise others that look the same, or is there something else going on?Presenter Anand Jagatia takes a deep breath and dives into the science. At the Blue Reef Aquarium in Portsmouth, Dr Lauren Nadler from the University of Southampton introduces us to some Blue Green Chromis fish to look for clues about how and why they form their large social groups. And we explore the smelly world of fish olfaction with Professor Culum Brown from Macquarie University in Sydney Australia. The mirror test is a classic way of trying to understand whether an animal can recognise itself or not. Professor Alex Jordan from the Max Plank institute in Konstanz, Germany explains how scientists place a visible mark on an animal, show it a mirror, and if the animal tries to rub it off, it suggests that the animal knows it’s seeing itself. A variety of apes, elephants and dolphins have passed with flying colours, but has a fish been able to take on the test? And are there really self-aware shoals drifting through our oceans?
 
Presenter: Anand Jagatia Producer: Emily Bird Editor: Ben Motley(Photo:Familiarity of the two fish. Portrait of a Hemichromis lifalili. Macro- Credit: kozorog  via Getty Images)

Do fish know what they look like?

Is silence blood-curdling or blissful? CrowdScience listener Ziqi finds it intolerable and thinks that there’s a good reason for it – silence is so rare in nature that it could be a signal for danger.  Presenter Marnie Chesterton is on a mission to test Ziqi’s theory, starting with her own tolerance for silence.  
She meets acoustic engineer Trevor Cox in the UK to find out whether silence is something we can measure. To do that she steps into an anechoic chamber, a place that’s designed to absorb all sound. In this most silent of silent places, what does silence actually sound like? Marnie also talks to researcher Eric Pfeifer in Germany, who is exploring the impact of spending time in silence and has evidence to suggest that it could be a positive experience. And neuroscientist Marta Moita in Portugal tells Marnie about how rats use silence to detect a threat in their environment. Her discoveries may hold the answer to Ziqi’s question. Presenter Marnie Chesterton Producer Jo Glanville Editor Ben Motley 
(Photo:Young woman covering ears ignoring loud noise, plugging ears with fingers annoyed by noisy neighbours - stock photo-  Credit: Mariia Vitkovska via Getty Images)

Why do I find silence unbearable?

Crowdscience listener Ryosuke grew up in Japan, and spent his childhood summers catching cicadas in the park. For people in Japan, the sound of their chirping signals the first true summer day. But until they emerge, these enigmatic insects live underground - often for many years. Ryosuke wants to know how they know the time is right, and CrowdScience is on the case. Presenter Anand Jagatia pieces together the story of the species, and meets the small but dedicated group of academics worldwide who’ve been able to study them.  In a field near Girona, Spain, he meets a scientist who’s spent the last twenty years counting them. How will a temperature probe help us work out when they might emerge, and what are they doing underground for so many years anyway? In nearby Barcelona, another scientist cuts open the stem of a tomato plant and Anand watches as the sap flows out. Could this be a clue to how cicadas sense what’s going on above ground? And he meets a cicada breeder in the US who has discovered a link between the life cycle of cicadas and the fruiting of a peach tree. Armed with that knowledge, can you really make time move faster for tree and insect alike? Presenter: Anand Jagatia  Producer: Robbie Wojciechowski Editor: Ben Motley(Photo:Cicada on Hosta Leaf - stock photo Credit: KenWiedemann via Getty Images)

How do cicadas know what season it is?

CrowdScience listener Limbikani in Zambia is always being told he has his Dad’s laugh, so he set us the challenge of trying to find out whether a laugh can be passed down in our genes or if it’s something we learn from our environment. Presenter Caroline Steel steps into the world of one of the world’s greatest laughter experts, Professor Sophie Scott, neuroscientist at University College London. In her office stuffed with memorabilia of a life filled with fun, they discuss how the shape of our bodies could play a role in how we laugh. Also joining the fun is Dr Gil Greengross, evolutionary psychologist at Aberystwyth University in Wales, UK. Gil tells us how Charles Darwin was the first person to question how laughter evolved.  Caroline also speaks to Dr Nancy Segal, Professor of Developmental Psychology and Director of the Twin Studies Center at California State University, Fullerton. Nancy is an expert in studies that demonstrate the role of nature vs nurture in how who we are and how we behave. She tells the story of the ‘Giggle Twins’, who were separated at birth but found they laughed identically when they met three decades later.  So does that mean that we really do inherit our laughs from our parents? Presenter: Caroline Steel Producer: Tom Bonnett Editor: Ben Motley Credit: The sound of rats laughing (slowed down so that our ears can detect the ultrasound) is courtesy of Dr. Jaak Panksepp(Photo: Father and son on yellow background- stock photo Credit: Georgijevic via Getty Images)

Did I inherit my laugh?

In 2025, the crack team of intrepid presenters here on CrowdScience have been on some incredible adventures. They’ve wondered whether water is wet, and gone a hunt for a missing tangerine. They’ve wondered why animals swallow rocks, imagined what would happen if the earth spun backwards and pondered whether atoms are immortal. But, as the year draws to a close, Anand Jagatia is wondering… have they REALLY been paying attention? Time to put them to the test! In this special programme, Anand gathers the other four presenters into a studio together – Caroline, Alex, Marnie and Chhavi, for an end-of-year quiz – and you can join in at home! Presenters: Anand Jagatia, Caroline Steel, Alex Lathbridge, Marnie Chesterton and Chhavi Sachdev Producer: Emily Knight Editor: Ben Motley(Photo: CrowdScience presenters in the studio with purple background Credit: BBC)

The CrowdScience quiz of the year

When some people are wandering around in shorts and a t-shirt, others are wrapped up in warm coats and jumpers. How come our responses to cold weather are so different? People have been living in cold environments for thousands of years. So why do some of us struggle with the cold more than others, and what, if any, adaptations have our bodies made to cope in freezing temperatures?  CrowdScience listener Anne from the UK is amazed by the warm houses of her neighbours, and wants to know whether her background might have affected her perspective on the cold.  Caroline Steel investigates, visiting a laboratory in Loughborough University, UK, that pushes the body to the extreme. Dr Matt Maley explains what happens inside our systems to help us survive the plummeting thermostat and how this adaption can vary from person to person. But it’s not just biological. Our culture impacts our experience of cold too. CrowdScience heads to Norway to meet the global community on the icy Arctic island of Svalbard. There Caroline meets Associate Professor Gunhild Sætren at the Arctic Safety Centre to find out the important role appropriate clothing plays in being prepared for the chilly weather. And we speak to Dr Cara Ocobock at the University of Notre Dame, USA, who tells us about her research comparing Finnish reindeer herders and office workers reactions to cold temperatures.  Presenter: Caroline Steel Producer: Hannah Fisher Editor: Ben Motley(Photo: Woman enjoying winter playing in fresh snow. Credit: Olga Pankova/Getty Images)

How do we adapt to the cold?

Smashing up guitars is a classic rock star activity, but how about drowning them? Seven-year-old listener Cornelius asked CrowdScience to find out what happens if you play a guitar underwater. Could this be the next avant-garde music sensation?  Host and amateur musician Caroline Steel tackles Cornelius’ question with the help of one increasingly soggy guitar. The UK’s National Physical Laboratory is our first port of call, with a guitar-sized water tank at the ready, and acoustic scientists Dr Freya Malcher and Ben Ford helping tackle our questions. Since an acoustic guitar’s sound is amplified by its internal chamber, what happens as that chamber starts to fill with water? How about if the whole guitar - strings, body and all - is submerged? What difference does it make if our ears are listening above or below the water? And can special water-adapted microphones help us explore this unusual question, before our guitar disintegrates? Our guitar then heads off on tour to Denmark, where the band Between Music have teased out questions just like these for their underwater music project, Aquasonic. We talk to violinist and Innovative Director Robert Karlsson, and singer Nanna Bech, who also plays a unique subaquatic instrument. With their help, we discover how to get the best out of a submerged guitar, and find out whether other instruments are better suited to the life aquatic. 
 
Presenter: Caroline Steel  
Producers: Cathy Edwards and Florian Bohr  
Editor: Ben Motley 
 
(Photo: Caroline Steel and Nanna Bech in an Aquasonic aquarium playing a guitar)

Can you play the guitar underwater?

Can we turn the world’s deserts green? CrowdScience listener Youcef is captivated by the idea of bringing water back to Earth’s driest landscapes. With sea levels rising and huge stretches of land drying out each year, he wonders whether redirecting seawater inland could offer a solution to both problems. Presenter Alex Lathbridge sets out to investigate starting with a kettle of salty water. Alex speaks to scientists about how deserts form, and how human actions like overgrazing can tip a fragile grassland into a barren landscape. He learns how the brightness of bare sand affects local weather, reducing cloud formation and rainfall. Researcher Yan Li reveals how huge solar and wind farms could darken and roughen the Sahara’s surface enough to double its rainfall, potentially kickstarting a self-reinforcing cycle of vegetation and moisture. But what about deserts where clouds already drift overhead? In the Atacama, one of the driest places on Earth, geographer Virginia Carter shows how fog harvesting nets can coax litres of fresh water from the air.  Alex also investigates desalination, where professor Chris Sansom is trying to harness solar power to remove the salt from seawater without burning vast amounts of fossil fuels. It is promising, but can it reduce the impact of rising sea levels? And what do you do with all the salt that’s left over?  Climate scientist Alan Condron proposes an even wilder idea: towing kilometre-sized icebergs from Antarctica to parched nations. His models show it might be possible, but the logistics verge on science fiction. Finally, plant scientist Zinnia Gonzalez Carranza warns that greening deserts isn’t just about adding water. Introducing new species, even hardy ones like mesquite, can trigger ecological chaos and harm the very communities who depend on these landscapes.  Presenter: Alex Lathbridge 
Producer: Sam Baker
Editor: Ben Motley (Photo: Palm trees growing in cracked, parched earth and the sun rising behind them. Credit: Danymages/Getty Images)

Can we turn deserts green?

When listener Sakura’s husband came home from his morning walk in Cambridgeshire, UK, he told her about a massive rainbow he’d seen. But when he showed her a picture, she didn’t think it was particularly large. So how big is a rainbow really? Are they always the same size? And if some are bigger than others, is there a limit? To find the answers, presenter Marnie Chesterton meets independent rainbow expert Philip Laven in a pitch-black studio to simulate how a rainbow is formed. He demonstrates how they are created by sunlight, reflecting and refracting in millions of little water droplets. But what does that mean for their size? Raymond Lee, retired professor from the US Naval academy, says that rainbows are not objects and don’t have a linear size, just a specific angular size that’s relative to the person seeing it. But Marnie doesn’t give up so easily – some rainbows still look bigger than others. In her journey to discover other ways to size up a rainbow, Marnie hears from Australian aerial photographer Colin Leonhardt who stunned the world with a beautiful picture. Next, assistant professor Ping Wah Li from The Chinese University of Hong Kong explains why it’s possible to come across more than one rainbow at a time.  And finally, atmospheric scientist Harald Edens shares another way to consider size, as well as how much he struggles to explain the complexity of rainbows to his four-year old daughter.  Presenter: Marnie Chesterton Producer: Florian Bohr Editor: Ben MotleyPhoto: Rainbow of Dreams - stock photo stock photo Credit: Laurent Fox via Getty Images)

How big is a rainbow?

Tears of joy, tears of sadness, tears of frustration or tears of pain - humans are thought to be the only animals that cry tears of emotion. CrowdScience listener Lizzy wants to know: why do we cry for emotional reasons? What is its evolutionary benefit? And why do some people cry more than others? It turns out that humans cry three types of tear: basal, reflex and emotional. The first kind keeps our eyes nice and lubricated and the second flushes out irritants such as fumes from the pesky onion, but the reasons for emotional tears are a bit harder to pin down. Using a specially designed tear collection kit, presenter Caroline Steel collects all three kinds of tears. With them safely stashed in tiny vials, she heads to the Netherlands, to Maurice Mikkers’ Imaginarium of Tears. Looking at her crystallised tears under a microscope will hopefully unveil a mystery or two. Marie Bannier-Hélaouët, who grew tear glands for her PhD, explains how the nervous system processes our emotions into tears. But why should we cry for both happiness and sadness, and for so many other emotions in between? Ad Vingerhoets, Professor of Clinical Psychology at Tilburg University, suggests we cry for helplessness - our bodies do not know how to process such intensity of feeling. But do these tears bring relief? Lauren Bylsma, Associate Professor of Psychiatry at the University of Pittsburgh, has been studying heart rates during crying episodes to find out. With her help, we also explore if women do in fact cry more than men, and why that might be. Presenter: Caroline Steel Producer: Eloise Stevens Editor: Ben Motley Photo: Fisheye woman having a cry - stock photo Credit: sdominick  via Getty Images)

Why do we cry?

Tsunamis destroy buildings, habitats and danger to everything in its path on land. But how do they affect life under the water? That's what CrowdScience listener Alvyn wants to know, and presenter Anand Jagatia is searching beneath the waves for answers. Anand meets Professor Syamsidik who is learning about how tsuanami waves are formed to help protect against future disasters. He runs the Tsunami and Disaster Mitigation Research Center at Universitas Syiah Kuala, Indonesia. With him at this state-of-the-art lab is Dr David McGovern, expert in ocean and coastal modelling at London South Bank University. David tells Anand how the energy of a tsunami is spread across the entire water column. To explain the forces at play, Anand chats to Professor Emile Okal a seismologist from Northwestern University in the United States. Tsunami wave can move as fast as 800 kilometres an hour but, despite this, out at sea you might not notice it - but can the same be said for marine life? We follow the wave as it nears land and all that force is contracted and begins to show its might. Professor Suchana 'Apple' Chavanich from Chulalongkorn University, Thailand was one of the first people to swim off the Thai coast after the 2004 tsunami and remembers how coral reefs were battered.
In Japan, after the 2011 Tohoku Earthquake and Tsunami as the water retracted it pulled with it tons and tons of debris into the water. The fishing communities of the Sanriku Coast lost almost everything, their equipment was destroyed and the water was heavily polluted. Anand meets Hiroshi Sato who set up the Sanriku Volunteer Divers, a team of people who dragged the debris out of the water. One of them was diver and journalist Bonnie Waycott who tells her story of witnesses the destruction first hand and trying to rescue the fishing industry with Hiroshi. Finally, we learnt that the effect of modern tsunamis carries far further than people might have imagined. On the west coast of the United States Professor Samuel Chan is an expert in invasive species at Oregon State University. He explains how modern infrastructure is contributing to some incredible migrations. Presenter: Anand Jagatia Producer: Tom Bonnett Editor: Ben MotleyPhoto: USA, California, Sonoma County, Bodega Bay, tsunami evacuation panel - stock photo Credit: Brigitte MERLE via Getty Images)

Do tsunamis affect marine life?

In your final moments, they say, you may walk down a tunnel of light. You might rise above your body, watching the scene below before passing into another world. Perhaps you’ll be met by glowing figures, see your life flash before your eyes, or feel a deep, unearthly calm. These are the stories of people who’ve reached the edge of death and returned. They’re not rare, nor random, and they have a name: near-death experiences. CrowdScience listener Steven in Chile first heard of them during a CPR class and wondered, are they fictitious? Psychologist Susan Blackmore once had an out-of-body experience as a student in Oxford, UK — floating above herself before soaring over the rooftops and dissolving into the universe. That single moment changed everything. She’s spent her career trying to understand what happened, and she believes such experiences are explainable. At the University of Michigan in the US, neuroscientist Professor Jimo Borjigin has done what few have dared: record the dying brain in action. Her studies show that even after the heart stops, the brain can produce powerful surges of coordinated activity, bursts that might explain the lights, the tunnels, and the sense of peace. She believes near-death experiences could become one of science’s most intriguing scientific frontiers for research into consciousness. At University College London in the UK, neuroscientist Dr Christopher Timmermann is exploring similar states using psychedelics, pushing the boundaries between self and oblivion to identify what induces a near-death experience and what we can learn about our consciousness along the way. Near death experiences, a paranormal mystery or explainable phenomenon? Presenter: Caroline Steel 
Producer: Harrison Lewis 
Editor: Ben Motley(Photo: Gap in the wall - stock photo  Credit: peterschreiber.media via Getty Images)

Are near-death experiences real?

For some they’re the stuff of nightmares, but many of us can’t get enough of horror films. For Halloween, CrowdScience investigates the science of why we enjoy films that scare the living daylights out of us. CrowdScience listener Maria from Taiwan is one of those people who would rather avoid frightening films, yet her husband loves them and is always trying to get her to watch with him. She wants to know why people like her husband are so drawn to horror films. To try and find out, presenter Anand Jagatia travels to the Recreational Fear Lab in Aarhus, Denmark, which is dedicated to understanding why people frighten themselves for fun. He meets the research lab’s directors Mathias Clasen and Marc Andersen who explain how horror and recreational fear could help us cope better with uncertainty, bond with those we are frightened beside, and perhaps even have some physical health benefits. They also take Anand to a haunted house, called Dystopia, which has used the Recreational Fear Lab’s research to become as terrifying as possible.  And we hear from horror film music composer, Mark Korven, who creates tension and fear using an invention he calls ‘the apprehension engine’. He speaks to BBC Naturebang’s Becky Ripley who has been investigating sounds that scare us and their evolutionary origins. Presenter: Anand Jagatia 
Producer: Jonathan Blackwell (Photo: Couple watch horror movie with blanket to cover their heads. Credit: WC.GI via Getty Images)

Why do people love horror films?

We all know insects are important, but one CrowdScience listener worries that they don’t seem to have equal billing when it comes to human love and attention. In Scotland’s capital Edinburgh, listener Ruth loves to sit and listen to the birds, the bees and the hoverflies as they go about their daily chores. And it’s got her wondering why bees and butterflies seem to get all the conservation efforts. What do we need to do to protect butterflies as less beautiful caterpillars, and ladybirds as less glamorous larvae? Are people even aware that insects exist in multiple stages of a lifecycle, and that around the world, insect populations are facing perilous levels of decline.  Presenter Alex Lathbridge is on a mission to identify the other unsung insect heroes. Along the way we meet Dr Caitlin Johnstone and Dr Nick Balfour at the Royal Botanic Gardens Edinburgh, who help listener Ruth find out about the lifestyles and lifecycles of hoverflies. We meet the midge that pollinates cocoa crops in Ghana, as well as Dr Tonya Lander from Oxford University and Dr Acheampong Atta-Boateng from the University of Arizona who have been studying them.  And Marc Vaez-Olivera from the company Polyfly introduces us to the billions of hoverflies helping to double avocado yields in Spain.  We also learn what we can all do to help keep insects in our gardens… even if that may involve sacrificing a cabbage or two. Presenter: Alex Lathbridge Producer: Marnie Chesterton Editor: Ben Motley(Photo: Caterpillar eating flowering plant with pink background - stock photo Credit: Raquel Lomas via Getty Images)

Should we help maggots and caterpillars?

How would you record a special moment? Maybe you could take a photograph, film a little video, or record some audio. We have lots of ways of recording what life LOOKS and SOUNDS like, but is the same true for the other senses? What if you wanted to record the smells that greet you on entering your favourite restaurant? Or record the way your loved ones hand feels in yours? These are the questions on the mind of listener Aravind, from California in the USA. He wants to know if there are any ways of recording and reproducing sensory experiences like taste and smell, or physical touch. Anand Jagatia is on the case, and is smelling, tasting, and quite literally FEELING his way to the answer. From a multi-sensory movie experience in Valencia, Spain, to the fascinating history of the pioneers of ‘scented cinema’, through to the ground-breaking “haptic technology” which is enhancing the capabilities of our sense of touch. Both for us, and for the robots which do the jobs we don’t want to. Presenter: Anand Jagatia Producer: Emily Knight Editor: Ben Motley(Photo: Woman making ASMR sounds with microphone and perfume on yellow background, closeup - stock photo. Credit: Liudmila Chernetska via Getty Images)

Can we record our senses?

Atoms are the building blocks of our world. Many have been around since right after the Big Bang created the universe nearly 14 billion years ago. And if life on Earth is made of atoms that are from all the way back then... will those atoms keep existing forever? That’s what CrowdScience Listener Rob in Australia would like to know.  Caroline Steel investigates the immortality of atoms by travelling to CERN, the world’s largest particle physics laboratory located along the border of France and Switzerland. There, theoretical physicist Matthew McCullough explains whether the smallest atoms can decay or survive the test of time. Physicist Marco van Leeuwen from Nikhef, the National Particle Physics Laboratory in the Netherlands, gives Caroline a behind-the-scenes tour of the ALICE experiment and the Large Hadron Collider at CERN. She learns how atoms are smashed at incredibly high speeds, and whether that might spell the end of an atom. And all life on earth is made up of atoms, but how does a collection of tiny particles become a living being? Astrobiologist Betül Kaçar from the University of Wisconsin, Madison, breaks down how life works from an atomic point of view.  Presenter: Caroline Steel Producer: Imaan Moin  Editor: Ben Motley (Photo: Hands cupping a glowing atom in the studio - stock photo. Credit: Paper Boat Creative via Getty Images)

Are atoms immortal?

Listener Jude in Canada wants to know why some animals are black and white. Why do zebras risk being so stripy? Why do pandas have such distinct marking? And do they have something in common? 
 
Presenter Caroline visits Pairi Daiza, a zoo in Belgium. Together with her guide for the day, Johan Vreys, she looks at these weird and wonderful animals up close. First, she visits three zebras having breakfast. Ecologist Martin How from the University of Bristol explains his ingenious experiment involving horses with zebra blankets. Next on the tour is the giant panda which, according to Prof Tim Caro from the University of Bristol, looks at the way it does to camouflage in snowy forests in China. But there are many more animals to see, and many more reasons to be monochrome, including the penguin and its tuxedo-like colouration.  Hannah Rowland, senior lecturer at the University of Liverpool explains that it might have more than just a single function. It turns out, scientific answers aren’t always black and white.  Presenter: Caroline Steel 
Producer: Florian Bohr 
Editor: Ben Motley(Photo: The zebra was running gracefully running in the green water. Credit: Surasak Suwanmake/Getty Images)

Why are some animals black and white?

Sometimes in science, when you try to answer one question it sparks even more questions.  The CrowdScience inbox is a bulging example of that. We get tons of new questions every week and many of those are following up on episodes we’ve made. Sometimes you want us to go deeper into part of the answer, or sometimes a subject intrigues you so much that it inspires further questions about it.  In this episode presenter Caroline Steel is on a mission to answer some of those questions. The CrowdScience episode How do fish survive in the deep ocean? led listener Ivor to wonder what sort of vision deep sea fish might have. On hand to answer that is Professor Lars Schmitz, Kravis Professor of Integrated Sciences: Biology, at Claremont McKenna College in the USA  Sticking with vision, we also tackle a question inspired by the CrowdScience episode Do we all see the same colour? For years listener Catarina has wondered why her eyes appear to change colour. Professor Pirro Hysi, ophthalmologist at the University of Pittsburgh, sheds some light on that subject.  In India, Rakesh listened to the CrowdScience episode Will the Earth ever lose its moon? and wondered about Jupiter’s many moons. The European Space Agency’s Ines Belgacem is working on a new mission to study Jupiter’s moons. She explains which of the giant planet’s ninety seven moons are ones for Rakesh to watch. We also hear how the episode Why can’t my dog live as long as me? caught the attention of listener Lisa... and her cat. She had us falling in love with the long history of falling cats and the scientists who study them. Caroline is joined by Professor Greg Gbur, physicist at the University of North Carolina, Charlotte in the USA and author of Falling Felines and Fundamental Physics.   Could this episode of follow up questions lead to an episode investigating the follow up questions to these follow up questions? Have a listen and, who knows, maybe you’ll find yourself inspired to email crowdscience@bbc.co.ukPresenter: Caroline Steel Producer: Tom Bonnett Editor: Ben Motley(Photo: Innovation and new ideas lightbulb concept with Question Mark - stock photo Credit: Olemedia via Getty Images)

Answers to even more questions

CrowdScience listener David is a bird whisperer.  On his family farm in Guinea, he would mimic the call of the black-headed weaver. He could replicate it so well that the birds would fly in close, curious to find out who was calling. David has been wondering if he was actually communicating with the weaver. In the foothills of the Austrian Alps is a research hotspot with a curious history. It was here that a scientist first began studying birds in their natural environment. That work continues today with Andrew Katsis from the University of Vienna, who knows the local flock of greylag geese by name. His research shows that animals aren’t just anonymous members of a group, they have personalities, relationships, and the ability to recognise one another. But what else do birds know? Thomas Bugnyar, professor of social behaviour and animal cognition, spends his time trying to get inside the mind of ravens. His work suggests they can understand their surroundings, make rational decisions, and even solve complex problems. Plus, we meet Ellie, a cockatoo with the ability to use a touchscreen computer to “talk.” She has a working vocabulary of more than 1,500 words. And when she presses a button, it would appear she is not just pecking at random, she is choosing purposefully, responding in ways that suggest birds may not only understand us, but communicate back. Presenter: Caroline Steel 
Producer: Minnie Harrop and Harrison Lewis 
Series producer: Ben Motley(Photo: Close up of Greylag goose with blue background Credit: Harrison Lewis, BBC)

Do birds understand us?

CrowdScience listener Kerry started thinking about his sentimental attachment to his possessions when he began sorting through an old trunk, full of objects from his past. He wants to know why we get so attached to things that often have no use anymore and why it’s so hard to give them away. Anand Jagatia investigates why the objects we accumulate during our lives mean so much to us. He talks to psychologists Mary Dozier and Melissa Norberg and finds out that our possessions offer stability and comfort from the earliest age. That keepsake you brought home from your holiday may also stir memories about days gone by - and that’s one reason why we may find it hard to part with the things we own, because they help us to access our emotions. And the items we collect through our lives can come to represent our identity too. Anand visits the Museum of Broken Relationships in Zagreb, Croatia, where people from all over the world have donated possessions from relationships that ended, whether romantic or family, and discovers that sentimental attachment is universal. Presenter Anand Jagatia Producers Jo Glanville and Imaan Moin Editor Ben Motley(Photo: Memories box in book shelf - Credit: Jan Hakan Dahlstrom via Getty Images)

Why am I so sentimental?

Milk: drink a lot of it and we’ll grow big and tall with strong bones. That’s what many people are told as children, but just how true is this accepted wisdom? CrowdScience listener JJ in Singapore is sceptical. He wants to live a healthy life for as long as possible, and he’s wondering whether drinking cow’s milk will help or hinder him on this mission. All mammals produce milk, and our mother’s milk is our very first drink as babies. So what actually is the white stuff? Mary Fewtrell, professor of paediatric nutrition at UCL, gives presenter Chhavi Sachdev the lowdown on just how fundamental breastmilk is to us all.
But are we meant to continue drinking milk from other animals once we grow up? This behaviour of ours is rare among mammals… so Christina Warinner, professor of evolutionary biology at Harvard University, tells us when in our history cow’s milk entered our diet, and how we even came to be able to digest it. And is there any truth in the accepted wisdom that cow’s milk will give us stronger bones? Karl Michaelsson, professor of medical epidemiology at Uppsala University, has researched just this – and the answer isn’t what you’d expect. Karl helps Chhavi sift through the complex evidence to see whether milk is actually any good for us.Presenter: Chhavi Sachdev
Producer: Sophie Ormiston
Editor: Ben Motley(Photo:Lady milking cow, Nadiad, Gujarat, India)

Will drinking milk help me live longer?

What will remain of us hundreds of millions of years from now? And how can we be so certain that we are the first technologically advanced species on Earth?These unsettling questions have been haunting listener Steve. If fossils can be lost to deep time through erosion and subduction into the Earth’s mantle, how would anyone — or anything — ever know that we had been here? And if an earlier species had built a civilization that rose and fell, would we even be able to find traces of it?To investigate, CrowdScience presenter Caroline Steel speaks to the scientists trying to answer these questions, while producer Sam Baker goes fossil hunting on the Jurassic Coast in the UK. Caroline speaks with astrophysicist Adam Frank at the University of Rochester in the US, who along with NASA scientist Gavin Schmidt developed the Silurian hypothesis – the idea that if an advanced species had existed deep in Earth’s past, they might have vanished without leaving a trace. But palaeontologists Jan Zalasiewicz and Sarah Gabbott from the University of Leicester in the UK argue that humans are already leaving an indelible mark in the form the chemical and material fingerprints we’re pressing into Earth’s crust. They contend that the ‘technofossils’ we are producing will last a very long time indeed.Along the way, Caroline and producer Sam discover just how rare fossils really are, how even the tiniest particles of pollution will give us away to far-future explorers, and why car parks might be our ultimate legacy. What they find is at once unsettling and oddly comforting: humanity could be fleeting, but our impact probably won’t be.Could we really have missed evidence of an ancient civilization? And what strange clues will we leave behind for whoever, or whatever, comes next? We explore Earth’s geological memory to find out.Presenter: Caroline Steel
Producer: Sam Baker
Editor: Ben Motley(Photo: Old phone embedded in concrete layer with defocused landscape background Credit: Petra Richli Via Getty Images)

How long will traces of our civilisation last?

Camouflage isn't just for chameleons! Military forces around the world deck their soldiers out in those distinctive green and brown uniforms, to give them the best chance of staying safe, and remaining undetected. But how do they work? Why do they look so different from country to country? And why do you still see soldiers wearing it in the city, when it can't possibly work as camouflage?
 
These are the questions in the mind of Crowdscience listener Paul, in Uganda. In his home of Kampala he often sees soldiers on patrol. As a botanist, he's fascinated by the nature-inspired designs, and he wants to know how they came to be. So Alex Lathbridge sets off to find out.
 
At Camolab at the University of Bristol, Laszlo Talas talks Alex through the history of battle-dress. There have been some extraordinary designs over the years, some of them quite beautiful in their way, and many with hidden easter eggs printed into the design!
 
In a patch of forest on the outskirts of Prague, Alex gets to try some of the latest gear out for himself. Fully kitted out in ghillie suit, camouflage chaps, face mask and goggles, he tries to disappear into tue background. With the help of 4M Tactical, the company who manufacture a cloak currently in use in Ukraine. It has the power to make you invisible, not just in the visible spectrum, but in the infrared too. With high tech sensors and infrared cameras now a staple of the modern battlefield, clothes like this are becoming essential.
 
Not all camouflage technology belongs to the military. Futuristic clothing company Vollebak in London are using 'the fabrics of the future' to design high tech streetwear for savvy 21st century urban warriors. Founder Steve Tindall shows Alex their prototype Thermal Camo Jacket, which uses hundreds of layers of graphene to give the illusion of heat, or cold. Steve says that hiding in plain sight is less about concealing yourself from human eyes, and more about avoiding the pervasive sensors and constant surveillance that are increasingly a feature of urban living.
 
Meanwhile in Sweden, they're taking the inspiration from chameleons more literally. Hans Karis, deputy research director of the Swedish defence institute FOI, introduces Alex to their Adaptive Camouflage, interwoven with a network of tiny coloured LEDs to change colour at will. It's not on the market yet, but perhaps chameleon soldiers will be a thing of the future.
 
Presented by Alex Lathbridge
Produced by Emily Knight(Photo: Thermal imaging of people in the woods)

How does camouflage work?

When listener Rob from Devon, UK, heard of a newly detected planet light years away, he was struck by the sheer scale the light must travel to reach us here on Earth. It got him wondering: How long does light last? What is the oldest light we have ever observed? And does light ever die? To find out, presenter Anand Jagatia calls on some of the brightest minds in astronomy and physics. Astronomer Matthew Middleton from the University of Southampton explains how scientists still struggle to define exactly what light is. What we do know is that light comes in many forms, and choosing the right kind can peel back the cosmic curtain, revealing the universe’s deepest and darkest secrets. That knowledge will prove vital in Anand’s search for the oldest light ever observed. At the European Southern Observatory in Chile, staff astronomer Pascale Hibon gives Anand a behind-the-scenes look at the Very Large Telescope, one of the most advanced optical instruments on Earth, perfectly placed under some of the clearest skies on the planet. Light from the objects Pascale studies has often travelled for billions of years, making her images snapshots of the distant past.If light has crossed the vastness of the universe to reach us, it must be unimaginably ancient. But what will become of it in the far future? Could we trap it and preserve it forever? Miles Padgett at the University of Glasgow, has spent his career trying to pin it down. As Anand discovers, physics can be more philosophical than you might expect. Presenter: Anand Jagatia 
Producer: Harrison Lewis 
Editor: Ilan Goodman(Photo: An area of deep space with thousands of galaxies in various shapes and sizes on a black background. Most are circles or ovals, with a few spirals. Credit:G. Östlin, P. G. Perez-Gonzalez, J. Melinder, the Jades collaboration, M. Zamani/ESA/Webb, Nasa and CSA)

How long does light last?

CrowdScience listener Rit, from Pune in India, is staring out of his window at the falling rain. It’s been pouring for four days now, and shows no sign of stopping. The laundry is piling up, all his shoes are wet, and he’s worried about the effect it’s having on the environment, and on agriculture. When it rains like this, the animals suffer, and the crops are destroyed. Cloud seeding and Weather Engineering are hot topics right now, and can bring the rain to places that need it. But Rit wants to know whether we can artificially stop the pouring rain, especially in an emergency. Following the devastating floods in Texas, it’s clearly not just a problem for countries with a monsoon season. Presenter Chhavi Sachdev is also sitting in a downpour at home in Mumbai. She dons her rain jacket and rubber boots to try and find out whether science can help Rit with his question. From controlling the clouds in India, to bringing rain to the deserts of the UAE, to firing high-powered lasers into the skies above Geneva, we find out what weather engineering is really capable of. With thanks to: Dr Thara Prabhakaran, from the Indian Institute of Tropical Meteorology Alya Al Mazroui, Director of the UAE Research Program for Rain Enhancement Science Jean-Pierre Wolf, Applied Physics Department of the University of Geneva Presenter: Chhavi Sachdev  
Producer: Emily Knight  
Series Producer: Ben Motley(Image: Girl carrying umbrella while standing on road against trees during rainfall. Credit: Cavan Images/Getty Images)

Can we stop the rain?

CrowdScience listener Jon started wondering how our teeth are created while he was in the dentist’s chair. It took his mind off the drilling. He wants to know how our teeth are made, what goes into them and how come we only get two sets of teeth when other animals, like sharks, grow thousands of new ones throughout their lives.Anand Jagatia goes back to prehistoric times to discover how the story of teeth began millions of years ago. Palaeontologist Yara Haridy explains that teeth weren’t designed originally for eating at all, but as a kind of armour on the exoskeletons of fish that was also sensitive to the environment. It turns out that our teeth in fact are part of our evolutionary success story. Biological anthropologist Peter Ungar reveals that we flourished as a species because our teeth are designed to get the maximum energy from our food. Anand discovers how teeth can even be grown in a lab when he meets researchers Ana Angelova Volponi and Xuechen Zhang whose team has managed to replicate the environment in which teeth develop. He also talks to Katsu Takahashi who has discovered a method for developing a third set of teeth. It’s a whole new way of creating teeth that will change the way we make them. Presenter Anand Jagatia 
Producer Jo Glanville  
Editor Ben Motley 
Studio Manager Bob Nettles 
Production co-ordinator Ishmael Soriano  
Translation, Katsu Takahashi interview Bethan Jones

How are teeth made?

The epic space story of a sci-fi dream that changed spaceflight forever. Told by the Nasa astronauts and team who made it happen.  Our multi-award-winning podcast is back, hosted by space scientist Maggie Aderin-Pocock. She tells the story of triumph and tragedy - of a dream that revolutionised modern space travel forever.You can listen to the trailer here. To hear episodes, search for 13 Minutes Presents: The Space Shuttle, wherever you get your BBC podcasts.  
 
13 Minutes Presents: The Space Shuttle is a BBC Audio Science Unit production for the BBC World Service.  
 
Theme music by Hans Zimmer and Christian Lundberg, and produced by Russell Emanuel, for Bleeding Fingers Music. 
 
Archive: 
Mission audio and oral histories, Nasa History Office.

Trailer: 13 Minutes Presents: The Space Shuttle

What comes to mind when you imagine the future of humanity? Could a computer make your mind more efficient? Enhance your cognition? Or cure a disorder you've been grappling with all your life? CrowdScience listener Mariana from Mexico hopes that one day technology will be able to help improve our brains.  Presenter Alex Lathbridge seeks out some of these brain boosters, exploring emerging technologies in deep brain stimulation at City St George’s University of London in the UK. Professor Francesca Morgante and Dr Lucia Ricciard explain how they’re using technology to treat Parkinson’s. And could brain technology help with even the most enigmatic elements of our minds? Dr Robert Hampson at Wake Forest University in the USA takes us through his research in restoring memory impairment.   Along the way we interrogate the ethical implications of the breakneck speed of progress in brain augmentation research with researcher Anders Sandberg from the Institute of Future Studies in Sweden.    Presenter: Alex Lathbridge  
Producer: Emily Bird  
Series Producer: Ben Motley

Could technology improve our brains?

Your whole life is governed by spin. The rotation of our planet tells you when to wake up, and Earth’s orbit around the Sun is the reason why some of us dig out a jumper for half the year and a t-shirt for the rest. But what if that all changed? 
 
That’s exactly what 8-year-old Geronimo in Ecuador wants to know. He and his dad, Fabian, have got themselves dizzy trying to figure out what would happen if the Earth stopped spinning, or better yet, started spinning in the opposite direction. Would everyone fly off into space? Would school be at night? Eager for answers, they decided to ask CrowdScience. Presenter Anand Jagatia embarks on an interstellar journey, blasting off with the celestial origins of spin itself. Astronomer Amy Bonsor from the University of Cambridge in the UK explains how Earth’s rotation began, with collapsing clouds of gas, planetary pile-ups and crushing gravitational force. At Keele Observatory, things get apocalyptic. Anand meets astronomer Jacco van Loon, who explains what would happen if Geronimo somehow waved a magic wand and brought Earth’s rotation to a halt. With months of unbroken daylight or darkness, devastating storms and even the loss of the Earth’s magnetic shield, it’s like the script of a disaster movie. Wave that magic wand again and we imagine a world where the Earth not only stops... but starts spinning the other way. Meteorologist Joao Basso from the University of Leipzig in Germany walks us through a mind-bending 2018 study that tells us the surprising things that would happen to the global climate.  Presenter: Anand Jagatia  
Producer: Harrison Lewis 
Series Producer: Ben Motley

What if the Earth spun backwards?

Here's a conundrum that has captivated scientists: when Earth formed 4.5 billion years ago, our planet was essentially a ball of molten rock. Any water that might have been present during the planet's formation would surely have boiled away immediately. Yet today, water covers about 70% of Earth's surface. So where did all this water come from? And more intriguingly, when did it arrive? Listener Bill in the USA wants to know, and Presenter Caroline Steel is after answers. Assistant Professor Muhammad Abdul Latif is an early earth physicist at United Arab Emirates University. He explains how his modelling has helped us to understand when water first appeared in our universe. The early earth was not a water-friendly place - a hellscape of molten rock, volcanic eruptions and constant bombardments from comets and asteroids, with high levels of solar radiation. These conditions would have evaporated the water. And according to Professor Richard Greenwood at Open University, our earth’s molten iron core would have been a ball of rust if there had been water in the proto-earth mix.  So if the water hasn’t always been here, where did it come from?  At the Natural History Museum in London, Professor Sara Russell has been comparing the isotopic "fingerprint" of Earth's water with water found in the asteroid Bennu, captured and  brought back by the recent Osiris Rex NASA mission. It’s a good match for earth’s water, but could it really be the answer to our question?  Presenter: Caroline Steel 
Producer: Marnie Chesterton 
Editor: Ben Motley(Image: Man overlooking the sea from cliff top. Credit: Gary Yeowell via Getty Images)

Where did Earth’s water come from?

Listener Dickson Mukisa from Uganda has been gazing up at the stars. But he’s not making wishes. He wants to know whether we can harness their energy, in the same way we do with our OWN star – the sun. After all, they may seem small and twinkly to us, but each one is a gigantic flaming ball of energy, with a power outputs averaging around 40 quadrillion kilowatt-hours per year – EACH! With somewhere between 100 and 400 BILLION stars in our own galaxy alone, that’s a lot of power! Can we get ‘solar power’ from stars that are such a long way away from earth? And what might we use it for? Alex Lathbridge heads to the University College London Observatory, to peer through the eyepiece of an enormous telescope and see some stars for himself. Professor Steve Fossey explains just how much of the light energy of the stars reaches us on earth. In other words, how BRIGHT they are. Once the starlight reaches earth of course, we have to capture it. Could traditional solar panels do the job? Alex meets Professor Henry Snaith from the University of Oxford, to find out about the future of photovoltaic technology, and why it could all be heading out to space. Once in space, things start getting weird! What if we made an enormous fleet of solar panels, and put them all into orbit around a star, soaking up every last drop of that precious energy? That might sound like science fiction, but the idea has been around for decades. It’s called a Dyson Sphere, or Dyson Swarm. Swedish researcher at the Insitute for Future Studies, Anders Sandberg explains how we might be able to build one around a neighbouring star... in around 10,000 years or so. But maybe it’s not all about light. Finally, Alex explores the mysterious, invisible energy of the ‘solar wind’, with Pekka Janhunen, Finnish physicist and inventor of the “E-Sail”, which might be able to harness the power of the stellar wind, too. Presenter: Alex Lathbridge 
Producer: Emily Knight  
Series Producer: Ben Motley(Image: Astronomer looking at the starry skies with a telescope. Credit: m-gucci via Getty Images)

Can we harness solar energy from other stars?

No one really cares that CrowdScience listener Sam has a younger brother, but they do care about his sister. In fact, they’re fascinated by her. That’s because Sam and his sister are fraternal twins. He’s been wondering all his life why he’s treated differently. Could it be cultural? Twins have long appeared in classical mythology, revered literature, and playful comedies—captivating artists and audiences alike across time and continents. Or is there something more scientific behind our fascination? Why are twins special? Anand Jagatia investigates with Karen Dillon from Blackburn College in the USA, who says it’s more complicated. Over the years we have created stereotypes of who and what twins are. Our perception has been warped by history and pop culture. As an identical twin herself, she knows firsthand how stereotypes can shape a twin’s identity. Philosopher Helena De Bres from Wellesley College in the USA believes these stereotypes play on human anxieties. Their similarities and differences are derived from their biology, maybe our genes have more of an influence over our personalities and behaviours than we like to think? And Nancy Segal agrees, Director of the Twin Studies Centre at California State University in the USA. She has spent her career studying twins. She’s found that nearly every trait, whether it be behavioural or physiological, has a genetic component to it. Anand is sure to leave you thinking that Sam, his sister and all the other twins across the globe, really are special! Presenter: Anand Jagatia  
Producer: Harrison Lewis 
Series Editor: Ben Motley (Image: Twin girls (8-10) wearing matching coats and pigtails. Credit: Jade Albert Studio, Inc via Getty Images)

Why are twins special?

Cycling is good for our health, good for the planet, and it can be an efficient way of moving around busy cities. But despite all the rational arguments for it, in most cities the number of people who get on their bikes is low.CrowdScience listener Hans wants to know whether it’s time to change our tactics. Could we persuade more people to cycle if we moved away from focusing on well-intentioned rational arguments and use messages that appeal to our desires and vanity instead? What does the science say? Presenter Caroline Steel is on the case.  She meets Winnie Sambu from World Bicycle Relief to learn about why people in countries like Kenya to choose the bike to get around. She heads out on a ride with psychologist Professor Ian Walker from the University of Swansea to find out what barriers there might be to persuading people to cycle. She also takes a lesson from one of the world’s top cycling nations as she talks to Marie Kåstrup, a cycling campaigns expert who has advised the Danish government on inspiring cycling and sustaining it in the city of Copenhagen. Also in Denmark, Caroline meets behavioural scientist Dr Pelle Guldborg Hansen who shares his experience in the art of persuasion. Presenter: Caroline Steel 
Producer: Tom Bonnett 
Series Producer: Ben Motley

How can we persuade more people to cycle?

Was there ever a time when life on earth was peaceful? Free of violence? No predators, no prey, just... vibes? Or has nature always been 'Red in Tooth and Claw'?  Have we always been eating each other? Our listener Scott sent us on a quest to discover the origins of predators and prey, and to find out what all this ‘eat or be eaten’ stuff is really about. Taking us back to the very dawn of life on earth, Professor Susannah Porter from the University of Santa Barbara lets Alex peer into an extraordinary world of microscopic warfare. It’s a dog-eat-dog (or, microbe-dissolve-microbe) world, with single celled organisms doing battle with each other. For billions of years, this was life on earth! Tiny, violent, and completely fascinating. But what about bigger creatures? More complex ones - animals? Speeding forward several billion years, Alex arrives in the Ediacaran Period – a time of unusual tranquility, where strange, plant-like animals lived in relative peace. At the Natural History Museum in Oxford, UK, palaeontologist Dr Frankie Dunn shows him around. So where did real predators come from, then? Alex is joined by Dr Imran Rahman as he ushers in one of the most extraordinary periods in Earth’s history – the magnificently named Cambrian Explosion! Here we find real predators, with teeth, claws, and impressive hunting appendages. Through the fossil record, we can see an arms race developing – as predators get more sophisticated, so does their prey. It’s ON. Finally, Alex wonders if our own evolution, shaped as it has been by this predator-prey arms race, might have been very different without the threat of being chomped. Professor Lynne Isbell from the University of California, Davis takes Alex on a trip into our primate past, and tackles one of our most fearsome predators: snakes. Presenter: Alex Lathbridge 
Producer: Emily Knight  
Series Producer: Ben Motley

Was there an idyllic time before carnivores?

In the dead of night at his home in Machinjiri, Malawi, CrowdScience listener John can hear a small, but persistent, hum. Whenever it’s quiet enough, the hum is there – but what’s causing it? And is John the only one who can hear it?Reports of consistent, low-pitched noise have been popping up around the world for decades. No one knows this better than Dr Glen MacPherson, who runs the World Hum Map. He tells presenter Caroline Steel his theory for what’s behind these hums.And Caroline does some investigating of her own. We visit the Isle of Lewis off the coast of Scotland, where residents are reporting a hum. We hear about the impact that persistent noise has on people’s lives, and find out… can Caroline hear the hum too?We also ask why some people can hear a hum but others can’t. We head to an anechoic chamber – one of the quietest places in the world – to speak to Professor Jordan Cheer, who puts Caroline’s low-frequency hearing to the test.From industrial activity to internally generated sounds, we sift through the noise to try and find out what could be causing listener John’s hum.Presenter: Caroline Steel
Producer: Sophie Ormiston
Series Producer: Ben Motley

What’s that background hum I hear?

Listener Christine wants to understand one of the strangest phenomena in the universe. But to get to grips with it, she’ll need a crash course in the bizarre behaviour of the very small. Here, things don’t act the way you might expect — and it’s famously hard to wrap your head around. Anand Jagatia has assembled some of the sharpest minds in the field and locked them in a studio. No one’s getting out until Christine and Anand know exactly what’s going on. Or at least, that’s the plan. On hand to help are Kanta Dihal, lecturer in science communication at Imperial College London; James Millen, King’s Quantum Director at King’s College London; and particle physicist Harry Cliff from the University of Cambridge. Prepare to enter the world of the very small—and the very weird—where particles can be in two places at once, influence each other across vast distances, and seem to decide what they are only when observed. Hear how these once-theoretical oddities are now driving a technological revolution, transforming everything from computing to communication. Presenter: Anand Jagatia  
Producer: Harrison Lewis 
Series Producer: Ben Motley

What on earth is quantum?

CrowdScience listener Saoirse is vegan and doesn’t eat honey. But she’s been wondering - might honey actually have environmental benefits, by giving bee populations a boost? To find out, presenter Anand Jagatia dons a bee suit and opens up some hives with biologist Dave Goulson, who reveals that there are over 20,000 bee species on earth – and not all of them need saving. Honeybee researcher Alison Mcafee talks about the importance of beekeeping for crop pollination, and why honeybee colonies around the world are collapsing. Although, as she explains, in some places beekeeping might actually be bad for endangered wild bees. We travel to Kenya to meet Loise Njeru and Lucy King, who show how the humble honeybee can be a powerful tool for conservation – helping to protect the mighty elephant. And, on a rooftop in London, former beekeeper Alison Benjamin explains how we can support the wild bee species that need our help. Producer and presenter: Anand Jagatia 
Location recording: Sophie Ormiston 
Series Producer: Ben Motley 
Production Co-ordinator: Ishmael Soriano

Can eating honey help save bees?

Bulgaria is famous for its yoghurt, a fermented milk food full of ‘good’ bacteria that has kept hungry Bulgarians healthy for over 4000 years. Inspired by that, and a question from a CrowdScience listener in California USA, Marnie Chesterton and Caroline Steel are immersing themselves in Bulgarian culture with a programme about Bulgarian cultures, recorded at the 2025 Sofia Science Festival. So, are the ‘live’ cultures in fermented foods actually alive by the time you eat them, and how can you tell? If you can eat the mould in blue cheese, can you eat the mould on cheese that isn’t supposed to be mouldy? Is traditional food really better for you? And if you put a drop of vanilla into a litre of milk, how come it all tastes of vanilla? Marnie and Caroline are joined by a chemist who was a member of Sofia University’s ‘Rapid Explosion Force’, a food technologist with a PhD in sponge cakes and a Professor of molecular biology who says that we contain so much bacteria that we’re only 10% human. With questions on food from around the world and from the audience in Sofia, Marnie and Caroline will be digesting the answers, as well as some local delicacies. Presenter: Marnie Chesterton & Caroline Steel
Producer: Emily Knight
Series Producer: Ben Motley

Is my yoghurt really alive?

You may have grown up hearing the saying “red sky at night, sailor’s delight, red sky in morning, sailor’s warning” - or maybe a variation of it. CrowdScience listener Alison, who sees many dazzling red skies from her home in the Yukon, Canada, certainly did. And now she wonders if the saying is a sensible prediction of coming weather or just another old wives’ tale. Alison and presenter Anand Jagatia run a little experiment, getting up at the crack of dawn and staying up until dusk for 5 days to record if the sunset and sunrise can predict their local weather. While we wait for the results, we track this weather proverb back to its ancient roots to find out how important it may have been to the people without satellites or even thermometers to guide them. We also tap into the expertise of modern-day weather predictors, meteorologists. What are the atmospheric pressure systems that cause red skies, and how do they influence the weather globally? And what exceptions to the rules might turn a trusty old proverb on its head? Presenter: Anand Jagatia 
Producer: Ella Hubber 
Series Producer: Ben Motley

Is red sky at night really sailor’s delight?

Some people fall asleep almost as soon as their head touches the pillow, while for others it can take hours of tossing and turning. CrowdScience listener Assia needs at least 45 minutes to get to sleep: it's always taken her a long time to drift off no matter how tired she is, and nothing seems to make a difference. She asked us to investigate.  Presenter Caroline Steel turns to experts to find out what happens in our bodies when we fall asleep, and why it’s more difficult for some than others. Eus van Someren explains how our bodies know when it’s time to get some rest and what can influence the difficulty of getting to sleep from our earliest years. Morten Kringelbach reveals that there may be more stages of sleep than we thought, and Ada Eban-Rothschild tells us why we have something to learn from the birds and the bees about getting a good night’s rest.   Caroline has trouble getting to sleep herself, and volunteers to have her sleep monitored in Cardiff University’s sleep lab. And we share some expert tips on falling asleep more easily. Presenter: Caroline Steel  
Producer: Jo Glanville  
Editor: Cathy Edwards 
Studio Manager: Jackie Margerum 
Production co-ordinators: Jana Holesworth and Josie HardyWith thanks to Professor Milton Mermikides for permission to include his composition ‘Transitions’. (Photo: Caroline Steel takes a nap in Cardiff University’s sleep lab)

Why can't I fall asleep?

According to the United Nations Food and Agriculture Organisation, 800 million people are going to bed hungry every night, but 2 billion people in the world are malnourished. Farmers across the globe produce enough food to feed 10 billion people, yet there are only 7.6 billion of us.  We know there is enough food to go around, but filling tummies is only the start – we also need a varied diet. CrowdScience visits Nairobi during GGIAR Science Week, a hub for agricultural scientists. They are meeting to discuss the changes needed to get the right crops into the soil and the right food on the plates of those who need it. Presenters Anand Jagatia and Alex Lathbridge are joined by a live audience and a panel of experts Lindiwe Sibanda, Sieglinde Snapp and Alex Awiti. Together they explore questions from our listeners in Kenya and around the world: whether we can restore natural habitats whilst promoting food security; why human waste isn’t used more commonly as a fertiliser; and what impact empowering women in agriculture will have on our ability to feed the world. Recorded at CGIAR Science Week at the UN headquarters in Nairobi. Image: Drone view of tractor ploughing a field
Image Credit: Justin Paget via Getty Images
 
Presenters: Anand Jagatia & Alex Lathbridge 
Producer: Harrison Lewis 
Editors: Martin Smith & Cathy Edwards 
Production Co-ordinators:  Ishmael Soriano & Josie Hardy
Studio Managers: Gayl Gordon, Andrew Garratt & Sarah Hockley

Can we feed everyone?

CrowdScience listener Sid is running late, and he’s turning to science to find an excuse. He and his partner Steffi in Singapore have very different attitudes to timekeeping. They wonder if this is down to their different cultural upbringings, or if they just had very different  brains to start with. Presenter Chhavi Sachdev puts her own time perception skills to the test to try to understand how subjective our sense of time can be. And we discover how the language we grow up speaking can influence the way we think about punctuality. Presenter: Chhavi Sachdev  
Producer: Emily Bird  
Editor:  Cathy Edwards 
Production Co-ordinator:  Ishmael Soriano  
Studio Manager: Jackie Margerum

Why am I always late?

What would you discover inside the stomach of a sea lion? CrowdScience listener Robyn found out first-hand when she volunteered at her local museum in Adelaide, Australia. The team dissecting the specimen removed around 30 rocks from the animal’s stomach, and Robyn wants the Crowdscience team to find out how and why they got there. Presenter Anand Jagatia uncovers a whole world of rock-munching creatures, from ostriches to ichthyosaurs. In search of answers we investigate Canadian sea lion research, and rummage through the vaults at the Natural History Museum in Bamberg, Germany.Presented by Anand Jagatia
Produced by Emily BirdImage: Australian Sea Lion (Neophoca cinerea), Hopkins Island, South Australia
Credit: Stephen Frink via Getty Images

Why do animals swallow rocks?

On the banks of the St Lawrence River in Quebec stands a 100-year-old lighthouse. While initially built to help boats navigate one of Canada’s most difficult waterways, the Point-de-Père site now also holds a different responsibility: it is a key reference for measuring sea levels around the entire North America continent.   But this is all set to change. With the development of new satellite technology, the tricky task of measuring sea levels is being updated - which could mean mountains around North America get brand new official heights. In this episode we revisit a question from CrowdScience listener Beth, who wondered about the elevation signs she saw scattered along a mountainous road, indicating how high above sea level she was. As sea levels rise, will all the elevation signs need repainting? And how do you measure sea level, anyway? 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. In fact, nothing on earth - not the sea, the shore or the mountains - is stable or constant, so the question of what you measure from and to becomes incredibly tricky. But that hasn’t stopped scientists risking life and fingers to use an ever-evolving array of technologies to find answers. Join host Marnie Chesterton as she dives into the mechanics of the latest sea level technology, and how it could make a big difference to understanding our unpredictable world. Presenter: Marnie Chesterton 
Producer: Julia Ravey and Marnie Chesterton 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano and Jana Holesworth 
Studio Manager: Emma Harth(Image: Elevation Sign Post, Rocky Mountain National Park. Credit: Stephanie Beverungen via Getty Images.)

How do you measure a mountain?

Host Anand Jagatia tackles gravity - a fundamental force of the universe yet also an everyday mystery that has baffled several listeners. Can you outrun it? Or at least use it to get fitter? If it varies, does that mean that you weigh less, depending on where on earth you stand? And if it’s the force of attraction between any objects with mass, are you technically more attractive after eating a massive cake? Professor Claudia de Rham from Imperial College London explains the basics of gravity, while we discover the best place on earth to weight ourselves, with Professor Paddy Regan from Surrey University and NPL Fellow in Nuclear and Radiation Science and Metrology. Anand takes a very fast spin on a special chair to experience extra gravity, thanks to Professor Floris Wuyts from the University of Antwerp, Kings College London and Minister of Science of Asgardia. And finally, we talk to an expert lined up at the other end of a hypothetical hole through the earth: Professor Richard Easther from the University of Auckland, New Zealand. What would happen if we fell straight through the earth? CrowdScience finds gravity a force to be reckoned with. Presenter: Anand Jagatia 
Producer: Marnie Chesterton 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano and Jana Bennett-Holesworth 
Studio Manager: Jackie Margerum and Duncan Hannant 
 
Photo: Anand Jagatia experiencing extra g-force

Where in the world will I weigh least?

Are food allergies higher in the West than the East? UK-based listener Jude wants to know the answer. Her daughter-in-law Min didn’t know anyone with food allergies when she was growing up in South Korea and thinks that they’re not so common there. Host Alex Lathbridge investigates. Along the way, he finds out what makes us sensitive to food allergies and how much that depends on our environment. He volunteers to have an allergy test, learns what triggers food allergies and tries to discover what lies behind their increase around the world.  Alex talks to some of the leading experts on food allergies in search for an answer to our listener’s question: Paul Turner breaks down what happens in our bodies when we have an allergic reaction; Jennifer Koplin explains why Australia tops the league table for food allergies and Michael Levin reveals what he found out in his ground-breaking research in South Africa comparing urban and rural populations. We also hear from Hana Ayoob, who grew up in Singapore and the UK, who describes what it’s like to suffer from multiple food allergies and describes the difference in cultural attitudes. Finally, we turn to Sooyoung Lee in South Korea to see if our listeners are right about the difference in rates for food allergies between East and West. Presenter: Alex Lathbridge 
Producer: Jo Glanville 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano 
Studio Manager: Duncan Hannant(Image: Young Asian father with cute little daughter grocery shopping for dairy products in supermarket Credit: d3sign via Getty Images)

Are there global food allergy hotspots?

CrowdScience listener Alina is in a relationship with a polyamorous partner and is very happy with this arrangement, which got her thinking – why is monogamy so often the norm in human societies?Presenter Caroline Steel goes on an anthropological odyssey to figure out where this drive to find a single partner - and stick with them - comes from.  What can science tell us about how human relationships developed, and whether having one or many partners is more 'natural'? Evolutionary biologist Kit Opie of the University of Bristol joins us at London Zoo to help us understand the mating systems of our closest primate relatives. To find out how polygamy developed in some parts of the world we speak to anthropologist Katie Starkweather of the University of Illinois Chicago. And we learn about the chemistry of bonding from Sarah Blumenthal at Emory University, who explains how the brains of prairie voles may give us clue about the neurochemicals which shape human relationships.  Presenter: Caroline Steel 
Producers: Priya Sippy, Ben Motley and Imaan Moin 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano 
Studio Manager: Steve Greenwood (Image: Dancing wedding cake figurines Credit: Peter Dazeley via Getty Images)

Are humans naturally monogamous?

The wetness of water seems blindingly obvious - but dive into the science and things aren’t so clear.  CrowdScience listeners Rachel and Callum were washing their hands one day and it got them thinking about wetness. Why does water feel the way it does? And what makes a liquid wet? To find out, presenter Anand Jagatia takes a closer look at the behaviour of liquids with materials scientist Mark Miodownik, and finds out why they might not be as wet as we think. We learn what’s really behind the sensation of feeling something wet on your skin, with the help of physiologist Davide Filingeri and PhD student Jade Ward.  And we turn to a philosopher, Vanessa Seifert, and a chemist, Tim Neudecker, to puzzle out exactly how many water molecules you need before the property of wetness emerges. Presenter: Anand Jagatia 
Producer: Anand Jagatia 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano 
Studio Manager: Bob Nettles and Andrew Garratt(Image: A photo of a droplet falling into a body of water Credit: Flaviu Cernea / 500pxvia Getty Images)

Is water wet?

It’s citrus season in the northern hemisphere, and fruit trees are bursting with oranges and lemons. But CrowdScience listener Jonathan wants to know what happened to the tangerines he ate as a child in the 1960s? He remembers a fruit that was juicy, sweet and full of pips, found each Christmas at the bottom of his stocking. Tangerines today, he thinks, just don't compare. Crowdscience tries to track down this elusive fruit. Presenter Anand Jagatia traces the tangerine's origins back to Ancient China, as botanist David Mabberley explains that the name ‘tangerine’ comes from a fruit that made its way from Asia, to Africa and the Moroccan port of Tangier, before arriving in the US in the early 1800s. Professor Tracy Kahn from UC Riverside tells us about the hybridisation process that goes into breeding modern tangerines, but says that while the season for these fruits has been dramatically extended, there’s a cost in terms of diversity and flavour.  Who better to help us track down this missing mandarin than a fruit detective? Well, that’s one of pomologist David Karp’s other job titles, and he reveals exactly which cultivar we might be looking for: the Dancy. So where can we find one? Over on Friend’s Ranches in Ojai, California, Emily Ayala shows us two trees planted by her late grandfather, and explains that nothing grown since really matches its unique flavour.So what will listener Jonathan think when we send him a box? Presenter: Anand Jagatia 
Producer: Marijke Peters 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano 
Studio Manager: Jackie Margerum(Image: Citrus oranges grow on tree, Hong Kong Credit: CHUNYIP WONG via Getty Images)

Whatever happened to tangerines?

Vermillion red, vibrant orange, golden yellows, even violet – we're enchanted by the colours that make up a stunning sunset or sunrise. CrowdScience listener Paulina, a lighting designer from Chile, often uses the sunsets she sees from her balcony as inspiration for her designs. And during the day and night, the sky can be all sorts of shades of blue. But Paulina wonders why, in the colour palette of the sky, she never sees any green. CrowdScience gazes skywards to investigate. Presenter Caroline Steel travels to the Arctic Circle to meet atmospheric physicist Katie Herlingshaw. Katie explains why we usually see the sky as blue, and what makes it transform into fiery reds and oranges at sunrise and sunset. We also peer into the science of perception, as neuroscientist Bevil Conway tells us what’s going on in our eyes (and brains) to make the colours we see in the sky. But there are some rare occasions when the sky can appear to be green, such as in a rainbow or a green flash at sunset. And then there is the spellbinding green glow of the aurora - the Northern and Southern Lights. We visit the northernmost aurora observatory in the world to try to understand this phenomenon. Are green skies more common than we think? Presenter: Caroline Steel 
Producer: Hannah Fisher  
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano 
Studio Manager: Sarah Hockley(Photo: View of sunset in Santiago, Chile. Photo montage courtesy of Paulina Villalobos)

Why isn't the sky green?

CrowdScience listener Dorit has a problem. She wants the tiles in her new bathroom to be arranged randomly but, no matter what she does, it still looks like they form some kind of pattern. This has got Dorit thinking about randomness – what is it, how do you create it, why do we find it so hard to recognise, and is anything really random at all? And if nothing is truly random, does it mean that everything is theoretically predictable? Tiling your bathroom is a much more existential problem than you might have thought. Never afraid of a question, whether big (is everything pre-determined?) or small (how do I tile my bathroom?), CrowdScience is on the case.Anand Jagatia heads to Switzerland to meet Hugo Duminil-Copin, a mathematician at the University of Geneva who specialises in probability theory. On the top floor of an old bank, Hugo has Anand flipping an imaginary coin in a random order. Hugo explains that randomness is something that cannot be predicted by any means – so why is it so easy for Hugo to guess what Anand’s next move is?Meanwhile, at the National Institutes of Mental Health in Maryland USA, Susan Wardle is a cognitive neuroscientist who researches how the human brain processes visual information. Can neuroscience help Dorit with her tiling problem, and is there a reason why the human brain likes to put random objects into some kind of order? Geneva is also the birthplace of the first Quantum Random Number Generator for smartphones, and CrowdScience has persuaded some of the University of Geneva’s finest quantum physicists to hook a photon detector up to a synthesiser. Thanks to Tiff Brydges and Nicolas Brunner, we can actually hear quantum particles behaving randomly. But is quantum randomness truly random, or just a pattern that we can’t see? And could quantum physics help Dorit tile her bathroom? Presenter: Anand Jagatia 
Producer: Ben Motley 
Editor: Cathy Edwards   
Production co-ordinator: Ishmael Soriano  
Technical producer: Jackie Margerum

Some of our biggest achievements happen in the first years of our lives. Taking our first steps, picking up a complex language from scratch, and forming relationships with some of the most important people we’ll ever meet. But when we try to remember this period of great change, we often draw a blank. After losing his Dad aged four, CrowdScience listener Colin has grappled with this. Why can’t he recall memories of such a monumental figure in his life, yet superficial relationships from his teens remain crystal clear in his mind? Colin takes presenter Marnie Chesterton to visit some of the significant locations of his childhood, places he would have spent many hours with his late father; and he recounts his earliest memories.On this trip down memory lane, Marnie discovers the psychological reason behind our lack of early childhood memories comes down to a phenomenon known as infantile amnesia. Tomás Ryan, neuroscientist at Trinity College Dublin, discusses some of the theories behind this universal experience, and Sarah Power from the Max Planck Institute for Human Development discusses her groundbreaking study exploring this form of forgetting in real time. Elaine Reese from the University of Otago digs into how our environment and culture can influence the age of our earliest memories, and why some of the first things we remember might not be the big, huge events you’d expect. And we hear about fascinating new insights from animal studies that hint these memories could still be lurking inside our heads... Presenter: Marnie Chesterton 
Producer: Julia Ravey 
Content Editor: Cathy Edwards 
Production Co-ordinators: Ishmael Soriano & Josie Hardy
Technical producer: Emma Harth(Photo: Marnie Chesterton and CrowdScience listener, Colin, on the swings in Belfast.)

Why can't I remember my early childhood?

Smartwatches are increasingly popular and many of us use these wearable devices to monitor our performance and improve our fitness. But how reliable is the data they collect, and can they actually make us healthier? CrowdScience listener Caitlin from Malawi is a big fan of her smartwatch. Her husband Fayaz, however, is much more sceptical of its accuracy, and has asked us to investigate. We meet up with them both at the gym, where Caitlin and presenter Caroline Steel put their fitness trackers – and themselves – to the test. We visit public health researchers Dr Cailbhe Doherty and Rory Lambe, who investigate the accuracy of wearable consumer devices, at University College Dublin. Caroline again pushes herself to the limit to see how her smartwatch results measure up to those from gold standard laboratory equipment. But is it crucial for smartwatches to be accurate? If they get us off the couch, is that what makes the difference to our health? Health behaviour expert Dr Ty Ferguson from the University of South Australia has studied this very question. And finally, how does quantifying our every move affect the way we think about ourselves and how we live? Professor Deborah Lupton from UNSW Sydney, shares some insights. Presenter: Caroline Steel 
Producers: Jo Glanville and Sophie Ormiston 
Editor: Cathy Edwards 
Technical producer: Sarah Hockley 
Production co-ordinator: Ishmael Soriano

Is my smartwatch good for my health?

While watching a feisty cockatoo chase after a hawk, CrowdScience listener Alison saw the hawk catch a thermal and rise effortlessly into the sky. The cockatoo gave chase, but the hawk climbed higher and higher until it became just a tiny speck, barely visible to the naked eye. And that got Alison thinking: just how high can birds go? Are there altitude limits for our feathered friends? Could a cockatoo, a sparrow, or even a duck reach such dizzying heights if they really put their wings to it? Presenter Alex Lathbridge sets out to investigate. Biologist Catherine Ivy reveals that life above the clouds isn’t easy. At high altitudes, the air is thinner, oxygen is scarce, and wings don’t generate as much lift. But some bird species have evolved incredible adaptations to overcome these challenges. Among them: bar-headed geese, renowned for their daring flights over the world’s tallest mountains. Physiologist Lucy Hawkes delves into how these geese defy the odds with their remarkable physiology, revealing the surprising discoveries she made while putting some of them on a treadmill. From super-powered hearts to clever lungs, we uncover the secrets behind nature’s impressive aviators. Presenter: Alex Lathbridge 
Producers: Ilan Goodman and Jeremy Grange 
Editor: Cathy Edwards  
Production co-ordinator: Ishmael Soriano 
Technical producer: Sarah Hockley(Image: OIE A TETE BARREE (Anser indicus) EN VOL Credit: Jean-Patrick DEYA / Contributor via Getty Images)

How high can birds fly?

Carbon footprints are a measure of how much we each contribute to the greenhouse gases that warm the Earth’s atmosphere. The global average of carbon dioxide emissions is nearly 5 tonnes per person per year, although it can be triple that in certain countries. But one CrowdScience listener in Ghana is wondering about the bigger picture. After all, humans aren’t the only species on this planet. So which other animal has the biggest carbon footprint? CrowdScience presenters Caroline Steel and Marnie Chesterton are on the case, examining and arguing over the animal that deserves the top spot for this title. Caroline, a vegan, points to the cow as the top contender, since the livestock sector produces 14.5% of total greenhouse gas emissions, and cows, whether as meat or dairy animals, are responsible for the majority of that. The team look at initiatives around the world to be more efficient with each animal out there. But maybe it’s time to put another sector in the spotlight? Pets. We love our dogs and cats but do their meat-based diets win them a place on the podium? From most loved to most detested, we look at the role that key pests play in upsetting the carbon budget. Could a small beetle with a large appetite for greenery be an unusual winner, thanks to the trees these pests destroy over their lifetimes? Is the biggest offender a carbon footprint, hoofprint, pawprint, or clawprint? Presenters: Caroline Steel and Marnie Chesterton 
Producer: Marnie Chesterton 
Editor: Cathy Edwards  
Production co-ordinator: Ishmael Soriano 
Technical producers: Sarah Hockley and Donald MacDonald

Which animal has the biggest carbon footprint?

In the past stout beer has been touted for its supposed health benefits. Is there any truth to those claims - and what happens if you take the alcohol out?CrowdScience listener Aengus pondered these questions down at the pub, after noticing most of his friends were drinking non-alcoholic beers. He wondered how the non-alcoholic stuff is made – what’s taken out and what’s added in – and whether the final product is better for you than the alcoholic version.It’s a question that takes us to Belgium, home to the experimental brewery of a global drinks company which takes the growing market for alcohol-free beer very seriously. David De Schutter, head of research and development, shows host Marnie Chesterton how to take alcohol out of beer without spoiling the flavour.We also find our way to a yeast lab in Leuven, Belgium where Kevin Verstrepen and his team have found another way to make alcohol-free beer with the help of industrious microbes: yeast varieties that brew beer without producing any alcohol in the first place. And how do they compare to the alcoholic versions? We discuss the importance of aromas in our perception of beer’s taste.So should listener Aengus stick to non-alcoholic stout? We speak to scientist Tim Stockwell about the health drawbacks of alcohol, even in moderation. And gut microbiome researcher Cláudia Marques fills us in on her delicious pilot study, which looked at the effects of both non-alcoholic and alcoholic beers on our digestive tract. Along the way, Marnie taste-tests what's on the market, and asks the experts why this particular grocery shelf has become so much bigger and more flavourful in recent years.Presenter: Marnie Chesterton
Producer: Sam Baker
Editor: Cathy Edwards
Production co-ordinator: Ishmael Soriano
Technical producers: Giles Aspen, Andrew Garratt and Donald MacDonald(Image: Close-up of waitress holding craft beer at bar, Brazil Credit: FG Trade via Getty Images)

Is beer better without alcohol?

When listener Diana fell on a run on her birthday, her first instinct was not to check her bruised hand, but instead to get up as quickly as possible and act as if nothing had happened. She felt embarrassed. Meanwhile, her son Marley loves to watch fail videos that, mostly, show people falling over. So why does falling – something that can cause serious injury – elicit both embarrassment and laughter? In the name of CrowdScience, presenter Caroline Steel trips, stumbles and falls. She spends a morning with clown Sean Kempton who teaches her slapstick skills, including how to do it safely.  Psychologist Rowland Miller explains why falling can be embarrassing and shares his theory of why humans have developed this emotion in the first place. Then it’s time for Caroline to try out Diana’s predicament herself. If a BBC presenter falls in a park, will she feel embarrassed? 
 
From embarrassment to laughter, psychologist Janet Gibson lists the ingredients of a funny fall, and humour expert Caleb Warren explains how they can get funnier with distance. Then Caroline tries, semi-successfully, to make members of the public laugh. Will clown Sean do a better job? Presenter: Caroline Steel 
Producer: Florian Bohr 
Editor: Cathy Edwards 
Production coordinators: Ishmael Soriano
Sound engineers: Bob Nettles, Tim Heffer and Giles Aspen

Why am I embarrassed when I fall?

Did you know that flies fly in rectangles, fish hide by lighting themselves up and the moon is lifting the ground underneath your feet? Anand Jagatia quizzes members of the CrowdScience team on the moments from the past year that had them scratching their heads in amazement. We hear Dr Erica McAlister’s attempts to calculate how many flies have ever existed, and about flies’ mating choreography, courtesy of Prof Jochen Zeil. We learn how to tell a mosquito’s sex thanks to Eggrey Aisha Kambewa and Dr Steve Gowelo. Astronomer Dr Darren Baskill describes tides not of water but of land; Dr Edie Widder paints a vivid picture of a camouflaged creature of the deep; and we explore starfishes’ five-fold symmetry with Dr Imran Rahman. Khimlal Gautam, Mountaineer and Chief Survey Officer for the Government of Nepal, tells us of the near-death experience he had when checking the height of Mount Everest. And finally, axolotl expert Dr Elly Tanaka is astonished at the dedication of CrowdScience presenter Alex Lathbridge to the subject of her research. Presenter: Anand Jagatia 
Producer: Ben Motley 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano 
Studio Managers: Donald MacDonald and Giles Aspen(Photo: Lost in formulas Credit: Cimmerian via Getty Images)

I didn’t know that!

The Moon has always sparked human curiosity. It governs the tides and biological rhythms. It’s inspired myths and stories. It’s inspired us to reach out and explore it. And it's certainly inspired CrowdScience listeners, who have sent us a host of questions about it. And in a special lunar-themed episode we’ve brought together a panel of astronomers and planetary scientists to help answer them.  What would life be like if there was no Moon? Would there even be life? Or what if we had two moons? Are the Moon and Earth equally battered by meteors? What would happen if an asteroid collided with the Moon? And could the Moon ever escape Earth’s gravity?   Anand Jagatia is joined by Prof Sara Russell, Head of the Planetary Materials Group at the Natural History Museum in London; Prof Neil Comins from the University of Maine, author of the book What if the Moon didn’t Exist?; and Prof Katarina Miljkovic from Curtin University in Perth, Australia. Presenter: Anand Jagatia 
Producer: Jeremy Grange 
Editor: Cathy Edwards 
Production Co-ordinator: Ishmael Soriano 
Studio Manager: Andrew Garratt(Photo: Landscape with the rising of the full moon during the golden hour Credit: Jose A. Bernat Bacete via Getty Images)

Will the Earth ever lose its Moon?

It seems bizarre to seek out experiences that are uncomfortable or downright painful. Yet examples abound: it’s common to eat painfully hot chillies, drink bitter coffee, or ‘feel the burn' when exercising - and enjoy it.
 
CrowdScience listener Sandy is baffled by this seemingly counterintuitive phenomenon, and has asked us to investigate. Presenter Anand Jagatia turns guinea pig as he tests a variety of unpleasant sensations, and unpicks the reasons we’re sometimes attracted to them.  
 
He meets chilli-eating champion Shahina Waseem, who puts Anand’s own attraction to spicy food to the test. Food scientist John Hayes explains how our taste receptors work and why our genes affect the appeal of bitter food. Neuroscientist Soo Ahn Lee describes her research looking at what happens in participants’ brains when they eat chocolate and capsaicin, the chemical that makes chillies hot.
 
As for the ‘pleasurable pain’ we sometimes experience when exercising, sports doctor Robin Chatterjee reveals the secrets of the ‘runner’s high’, while neuroscientist Siri Leknes explains why the feeling that something’s good for us can make discomfort pleasurable.
 
Presenter: Anand Jagatia
Producer: Jo Glanville
Editor: Cathy Edwards
Production co-ordinator: Ishmael Soriano
Sound engineer: Sue Maillot(Image: Young man have bath in ice covered lake in nature and looking up, Czech Republic Credit: CharlieChesvick via Getty Images)

Why does pain sometimes feel good?

For their fans, jigsaw puzzles are a satisfying challenge, a focus, a chance to put everything else aside for a moment and be creative. But for other people they’re a frustrating jumble of random shapes and colours, a pointless task which is best left in the box.
 
CrowdScience listener Heather is definitely a fan. She loves doing jigsaw puzzles and she wants to know why some people are so good at them. What skills do you need to find a pattern amongst all those shapes and colours? How do our brains, eyes and hands assemble the fragments into the finished article? And why do we enjoy doing them anyway?     
 
Presenter Alex Lathbridge puts together the pieces to answer Heather’s question. He sits down to work on a jigsaw with Sarah Mills, the ten-times UK jigsaw puzzling champion (yes... competitive jigsaw puzzling really is a thing!) As he watches Sarah complete the puzzle at lightning speed he gets a few of her top tips. 
 
So what’s going on in our brains when we’re doing a jigsaw puzzle? How do we recognise and process colour and shape? Prof Mark Mattson from Johns Hopkins University in the USA has the answer. And it’s all to do with a little seahorse-shaped part of the brain called the hippocampus. Alex also explores the effect of jigsaws on our brains with neuropsychologist Dr Patrick Fissler. He’s carried out research to investigate the benefits of jigsaw puzzles on our brains as we grow older. Both listener Heather and ten-times-champion Sarah seem to be better at jigsaws than Alex is. So, based on that sample size of three, women are superior puzzlers compared to men! But has anybody actually cast the net wider to see if that’s really the case? Alex talks to Daniela Aguilar from the University of Lethbridge in Canada about her study to investigate exactly that – and she reveals the results. 
 
Heather’s also wondering if any other species enjoy puzzles. And it seems they do! Alex meets Dr Cody McCoy from the University of Chicago to find out about the optimistic, tool-using crows of New Caledonia. From crows to competitive puzzlers, it seems we all relish a challenge!Presenter: Alex Lathbridge
Producer: Jeremy Grange
Editor: Cathy Edwards
Studio Manager: Bob Nettles
Production Co-ordinator: Ishmael Soriano

Why am I good at jigsaw puzzles?

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 is around a building or a city, is an important everyday capability, one that has been integral to human survival. This week CrowdScience listener David wants 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? Professor Hugo Spiers from UCL shares his latest lab for researching navigation and tells us that the country you live in might be a good predictor of your navigation skills.  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, with Prof Veronique Bohbot what an over-reliance on GPS technology might do to our brain health. Presenter: Marnie Chesterton 
Producer: Melanie Brown(Photo: Man standing on rural road holding up a road map, head obscured by map. Credit: Noel Hendrickson/Getty Images)

Can I improve my sense of direction?

As we enter our teenage years, many of us feel like life is just getting started. But for dogs, celebrating a ‘teen’ birthday is a sign of old age, entering a phase when things start slowing down. Listener Susan was besotted with her beloved corgi Copper John and wants to know why our furry companions rarely live as long as us.
 
We investigate what accounts for the huge differences in lifespans across animal species. From fish that live a few weeks, to sharks who can survive for 500 years, what are the factors that affect the ticking on our biological clocks? Central to this field is the idea of ‘live fast, die young’, with some animals burning more quickly through their ‘life fuel’. But is this rate set in stone?Presenter Anand Jagatia find out how animals’ growth, reproduction and anti-ageing methods contribute to the length of their survival. Dr Kevin Healy, a macroecologist at the University of Galway, discusses some of these theories, explaining how the dangers and luxuries faced by animals during their evolution shape their speed of life. One example of extreme slow living is the Greenland Shark. John Fleng Steffensen, Professor of Marine Biology at the University of Copenhagen, describes how he helped figure out how old they really are, and how their cold living quarters increase their lifespan. Alessandro Cellerino, physiologist at the Scuola Normale Superiore in Pisa, finds the key to the sharks’ longevity in their DNA.Anand also goes on a hunt on the west coast of Ireland for a creature that lives fast but surprisingly, dies old. Noel Fahy, research student at the University of Galway, is his guide, while Dr Nicole Foley, Associate Research Scientist at Texas A&M University, reveals the life-extending secrets of this creature.And geneticist Trey Ideker, Professor at the University of California San Diego, busts the myth that one dog year is seven human years. But how much is this misconception off by?Presenter: Anand Jagatia
Producer: Julia Ravey
Content Editor: Cathy Edwards
Studio Manager: Sarah Hockley
Production Coordinator: Ishmael Soriano(Photo: Copper John the Welsh Pembrokeshire Corgi, by listener Susan)