CrowdScience

• Where did Earth’s water come from?

  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)

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• Why are twins special?

  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)

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• Was there an idyllic time before carnivores?

  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

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• Can eating honey help save bees?

  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

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• Is my yoghurt really alive?

  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

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