CrowdScience

Hosted by BBC World Service

Technology Science

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508

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Aug 2026

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About the show

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

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60 recent

October 2, 202626 min

How are shells made?

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)

September 25, 202626 min

Do plants know we're here?

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)

September 18, 202634 min

How many dead people are on the internet?

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)

September 11, 202626 min

Can my veggie sausages save the world?

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)

September 4, 202629 min

Why do I love rollercoasters?

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)

September 2, 202626 min

How do electric fish make electricity?

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

August 21, 202626 min

Why am I warm blooded?

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)

August 14, 202626 min

Why can't I concentrate?

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)

August 7, 202626 min

Why is TB still killing people?

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 Chesterton Producer: Marnie Chesterton Editor: 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)

July 31, 202637 min

Will I get hit by a meteor?

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)