Are we mature by 18?

CrowdScience listeners David and Tatiana have long been captivated by an unusual dinner table discussion: the peculiar change they’ve noticed over the past 16 years in the sunlight streaming through their bedroom window in Ostend, Belgium. They’re convinced that the room has not only become sunnier but that the actual angle of sunlight has shifted.Intrigued by their observations, we head to Ostend. Our mission: to investigate three of their theories, enlisting expert help along the way.Theory 1 – A celestial anomaly? René Oudmaijer at the Royal Observatory of Belgium considers whether our shifting position in the solar system might explain the change.Theory 2 – Movement in the Earth’s crust? Alejandra Tovar from the Geological Survey of Belgium examines tectonic data to see if the Earth’s crust is moving enough to alter the angle of sunlight.Theory 3 – Subsidence? Structural engineer Kath Hannigan helps us inspect the building for signs that it may be sinking or twisting.And we explore one final theory of our own, enlisting memory expert Julia Shaw to examine whether it could all be a trick of the mind. Will the team crack the case?Presenter: Caroline Steel Producer: Harrison Lewis Editor: Cathy Edwards Production co-ordinator: Ishmael Soriano Studio Manager: Sarah Hockley(Photo: CrowdScience listeners David and Tatiana standing in front of a window in their house)

Fungi are a mysterious and understudied life form. And to add to the intrigue, some of them actually glow in the dark. This phenomenon has sparked CrowdScience listener Derek's curiosity, and he's asked us to investigate.Presenter Caroline Steel gets on the case. This is just one example of the natural wonder that is bioluminescence – living organisms that glow. How do they produce their light, and is there any reason for it? Caroline visits a bioluminescent bay in Puerto Rico, and Dr Brenda Soler-Figueroa explains what makes it sparkle.But it turns out there are many different explanations for why living things glow. Fungi, which listener Derek is particularly interested in, are neither plants nor animals, but an entirely different kingdom of life that we know much less about. Professor Katie Field takes on the task of trying to grow us some bioluminescent mushrooms, while Prof Cassius Stevani explains how – and importantly, why – they glow.And finally – could we ever harness the power of bioluminescence to our advantage in the future?Presenter: Caroline Steel Producer: Hannah Fisher Editor: Cathy Edwards Production co-ordinator: Ishmael Soriano Studio Manager: Neva Missirian(Photo: Omphalotus nidiformis, or ghost fungus, Penrose, NSW, Australia Credit: Louise Docker Sydney Australia via Getty Images)

Can learning new languages make us forget our mother tongue? CrowdScience listener Nakombe in Cameroon is concerned that his first language, Balue, is slipping from his grasp. He has learned multiple languages through his life, but Balue is the language of his family and home. It’s central to his identity and sense of belonging. So why does it seem to be fading from him, and what can he do to get it back?We search for answers, investigating what happens in our brains when we struggle to recall languages, as well as the social and economic factors that lead to language loss. Presenter Anand Jagatia asks Michael Anderson from the University of Cambridge, an expert on memory and forgetting, whether forgotten languages disappear from our brain, or just become difficult to access. Linguist Monika Schmid from the University of York takes us through the phenomenon of first language attrition, and has words of reassurance and advice for Nakombe and others in his situation.And we meet Larry Kimura from the University of Hawai’i at Hilo, a pioneer of Hawaiian language revitalization, and Gabriela Pérez Báez, an expert in indigenous languages and language revitalization at the University of Oregon. They explain why languages around the world become threatened, and how to keep them alive.Presenter: Anand Jagatia Producer: Margaret Sessa Hawkins Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Managers: Sarah Hockley and Omera Ahamed(Photo: Diccionario, Argentina Credit: PonyWang via Getty Images)

While there is a myriad of deodorants, shower gels and perfumes helping us stay fresh and fragrant today, that hasn’t always been the case. How did humans stay clean in the past, or did they not care so much? And is there an evolutionary reason for human body odour in the first place? These are questions that CrowdScience listener Sarah has pondered on trips in her camper van, when she wants to keep clean, but washing isn’t always convenient. In search of answers, presenter Anand Jagatia delves into the sweaty details: where body odour comes from, why some people's armpits don't smell, and whether this heady stink serves any purpose. Could our natural odour really help to attract a partner, or is it just a smelly bacterial by-product? Anand explores the intriguing mystery of human pheromones, and hears how for hundreds of years, Europeans were terrified of washing. Contributors: Dr Madalyn Nguyen, Dermatologist Dr Kara Hoover, Biological Anthropologist, University of Alaska Fairbanks Katherine Ashenburg, author, The Dirt on Clean: An Unsanitized History Dr Tristram Wyatt, Department of Biology, University of Oxford Presenter: Anand Jagatia Producer: Sophie Eastaugh Production co-ordinator: Ishmael Soriano Editor: Cathy Edwards Sound engineer: Emma Harth(Photo: Girl sweating smelly armpit, Taiwan Credit: PonyWang via Getty Images)

2024 is the biggest election year in history. From Taiwan to India, the USA to Ghana, by the end of the year almost half of the world’s population will have had the chance to choose who governs them. But there are a huge number of possible voting systems – and listener James wants CrowdScience to find out which is the fairest. To do so, we create a fictional country called CrowdLand to try out different electoral systems. Presenter Caroline Steel consults mathematician David McCune and political scientists Eric Linhart and Simon Hix, and we hear from listeners around the world about how they vote in their respective countries. Can we find the perfect voting system for CrowdLand? Contributors: Prof David McCune, William Jewell College, USA Prof Eric Linhart, University of Technology Chemnitz, Germany Prof Simon Hix, European University Institute, Italy Actors: Charlotte Bloomsbury Ross Virgo Presenter: Caroline Steel Producer: Florian Bohr Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Donald MacDonald(Image: Hand of a person casting a vote into the ballot box during elections, Thailand Credit: boonchai wedmakawand via Getty Images)

With huge heads on top of spindly stalks, how do sunflowers defy gravity to stay standing? That was a question sent to CrowdScience by listener Frank, whose curiosity was piqued by the towering sunflowers on his neighbour’s deck. They stay up not only when the weather is fine, but, even more impressively, during strong winds. Could this feat of strength, flexibility and balance inspire the construction of tall buildings? It's a question that takes presenter Anand Jagatia to a sunflower festival in England, to see how the sunflower’s long evolutionary lineage has honed its structure. And from tall flowers to tall buildings, we turn to structural engineers, asking how these concepts factor into the design of the world’s tallest skyscrapers. Can ideas drawn from sunflowers or other natural structures help buildings withstand wind, or even storm surges?Contributors: Stuart Beare, partner and grower at Tulley’s Farm Roland Ennos, Visiting Professor in Biological Studies, University of Hull Sigrid Adriaenssen, Professor of Civil and Environmental Engineering, Princeton University Koichi Takada, founder of Koichi Takada Architects Presenter: Anand Jagatia Producer: Tom Bonnett Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Bob Nettles(Image: Tall Sunflower blooming in a field, Melbourne, Victoria, Australia Credit: Naomi Rahim via Getty Images)

The Moon and Earth are drifting gradually further apart. Every year the gap between them increases by a few centimetres. We know that the Moon’s gravity has an important effect on Earth - from controlling the tides to affecting the planet’s rotation - but slowly, imperceptibly, over billions of years, that influence will diminish as the Moon moves away. For CrowdScience listener Tony in the UK that idea poses another question. What if we were to look back in time? What effects did the Moon have when it was closer to Earth? Would it counteract the planet’s gravity more so that, at the time of the dinosaurs, a Brontosaurus would weigh a little less that it would if it existed now? It’s an intriguing question. And, given that it involves both the Moon AND dinosaurs, it’s one that’s got presenter Anand Jagatia really excited! Anand begins his journey on Brighton beach on the South coast of the UK. He’s there to watch the full Moon rise - and get a few insights on Tony’s question - from astronomer Darren Baskill and astrophotographer (and cellist) Ivana Perenic. Anand talks to Darren about the influence of the Moon’s gravity on Earth today. As they stand on the beach, with the sea lapping at their feet, they can certainly see its effect on the ocean tides. But did you know that the Moon also causes tides on the land as well? Every time it’s overhead the ground you’re standing on is higher by a few centimetres. Professor Neil Comins, author of the book What If the Moon Didn’t Exist, explains why the tides are the reason the Moon is moving away from Earth – and it has been ever since it was first formed. And how was it formed anyhow? We turn back time with Prof. Sara Russell from the Natural History Museum in London to discover one of the most dramatic events in the early history of our solar system... when two worlds collided. And, of course, it helps to know what a dinosaur weighed in the first place. Anand turns to paleontologist Nicolas Campione, who’s been puzzling over the most accurate way to calculate the bulk of a Brontosaurus. Contributors: Dr. Darren Baskill, Astronomer, University of Sussex, UK Ivana Perenic, Astrophotographer Dr. Nicolas Campione, Paleontologist, University of New England, Australia Prof. Sara Russell, Cosmic Mineralogist, Natural History Museum, UK Prof. Neil Comins, Astronomer, University of Maine, USAPresenter: Anand Jagatia Producer: Jeremy Grange Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Jackie Margerum(Image: Tyrannosaurus Rex and Spinosaurus in front of the moon - stock photo Credit: MR1805via Getty Images)

18 is the age of majority, or maturity, in most countries around the world. Depending where you live, it might be when you can vote, buy alcohol, or get married. But what's so special about 18 that makes it the beginning of adulthood? CrowdScience listener Lynda didn't feel very mature back then. She recalls a difficult decision that made her wonder what science has to say about when we’re truly grown up. How developed are we, physically, mentally and emotionally, by the age of 18? And how much does this differ between people, or from culture to culture? Presenter Caroline Steel digs around for answers with the aid of neuroscientist Sarah-Jayne Blakemore, biological anthropologist Barry Bogin, and cultural anthropologist Bonnie Hewlett. And even some teenagers. Contributors: Barry Bogin, Emeritus Professor of Biological Anthropology, Loughborough University Sarah-Jayne Blakemore - Professor of Psychology and Cognitive Neuroscience at the University of Cambridge Professor Bonnie Hewlett - Associate Professor, Cultural Anthropology, WSU VancouverPresenter: Caroline Steel Producer: Richard Walker Editor: Cathy Edwards Production Co-Ordinator: Ishmael Soriano Studio Manager: Neva Missirian

An apex predator is a killer. Usually large and terrifying, they enjoy the privilege of life at the top of a food chain. Nothing will eat them, leaving them free to wreak carnage on more vulnerable creatures. In biology, it’s a term normally reserved for animals like polar bears, tigers and wolves. But CrowdScience listener Eoin wonders whether there’s a non-animal candidate for apex predator: the car. After all, worldwide, more than 1.5 million humans die on the roads each year, while pollution from traffic kills millions more. And that’s just the impact on us. What are cars doing to all the other species on this planet? Host Anand Jagatia hits the road to investigate. En route, we’ll be picking up some scientists to help answer the question. It turns out to be so much more than a question of roadkill: cars, and the infrastructure built to support them, are destroying animals in ways science is only now revealing. How did the wildlife cross the road? We go verge-side to test four different approaches. And we hear how cars manage to kill, not just on the roadside, but, in the case of some salmon species, from many miles away. Gathering as much evidence as possible, we pass judgement on whether the car truly is an apex predator. Contributors: Samantha Helle - Conservation Biologist and PhD student, University of Wisconsin–Madison Paul Donald – Senior Scientist, BirdLife International and Honorary Research Fellow, University of Cambridge Zhenyu Tian – Environmental Chemist and Assistant Professor, Northeastern University Presenter: Anand Jagatia Producer: Marnie Chesterton Reporter: Camilla Mota Editor: Cathy Edwards Studio manager: Donald MacDonald and Giles Aspen Production co-ordinator: Ishmael Soriano(Image: Illustration of a deer in front of a car - stock illustration Credit: JSCIEPRO/SCIENCE PHOTO LIBRARY via Getty Images)

Many of us experience an inner voice: we silently talk to ourselves as we go about our daily lives. CrowdScience listener Fredrick has been wondering about the science behind this interior dialogue. We hear from psychologists researching our inner voice and discover that it’s something that begins in early childhood. Presenter Caroline Steel meets Russell Hurlburt, a pioneering scientist who devised a method of researching this - and volunteers to monitor her own inner speech to figure out what’s going on in her mind. She discovers that speech is just part of what’s going on in our heads, much of our inner world in fact doesn’t involve language at all but includes images, sensations and feelings. Caroline talks to psychologist Charles Fernyhough, who explains one theory for how we develop an interior dialogue as young children: first speaking out loud to ourselves and then learning to keep that conversation going silently. No one really knows how this evolved, but keeping our thoughts quiet may have been a way of staying safe from predators and enemies. Using MRI scanning, Charles and Russell have peered inside people’s brains to understand this interior voice and found something surprising: inner dialogue appears to have more in common with listening than with speaking. Caroline also has an encounter with a robot that has been programmed to dialogue with itself. Which leads us to some deep questions: is our inner voice part of what makes us human, and if so, what are the consequences of robots developing this ability? Scientist Arianna Pipitone describes it as a step towards artificial consciousness.Featuring: Professor Charles Fernyhough, University of Durham, UK Professor Russell Hurlburt, University of Nevada, Las Vegas, USA Dr Arianna Pipitone, University of Palermo, Italy Presenter: Caroline Steel Producer: Jo Glanville Editor: Cathy Edwards Sound design: Julian Wharton Studio manager: Donald MacDonald Production co-ordinator: Ishmael Soriano(Image: Mixed Race boy looking up Credit: Jose Luis Pelaez Inc via Getty Images)