CrowdScience

In most cultures, the soundtrack to our lives is one of optimism. We are told to aim for the stars, dream big and believe that tomorrow will definitely be a better day. But why do so many people subscribe to the cult of 'glass half full' when life’s hardships should make any reasonable person a bit more wary? Listener Hannah from Germany - a self-described pessimist - is intrigued as to whether the optimistic way of life is really the best way to be. Taking on the challenge is Marnie Chesterton, who finds out why 80% of the population have an optimism bias and how the ability to hope and take risks may have helped the human species get where it is today. She also meets a man who pushes the optimistic outlook to its very limits - Base jumping world champion, Espen Fadnes. Listener Hannah on the other hand looks into the psychology of pessimism to find out if there are any advantages to her less rose-tinted view on life - and whether the culture we grow up in shapes how realistically we see the world.Producer: Caroline Steel Presentet: Marnie ChestertonContributors: Espen Fadnes – Freefall professional Tali Sharot – Professor of neuroscience, UCL Julie Norem - Professor of psychology, Wellesley College Jeanne Tsai - Professor of psychology, Stanford(Image: Two arrows, one with a sad smiley and the other with happy smiley, pointing in opposite directions. Credit: Getty Images)

Cats started hanging out with humans thousands of years ago, and nowadays these fluffy, lovable pets are found in many of our homes. But there is no doubt lots of them still have keen hunting instincts - witness all the birds and small mammals they kill each year.CrowdScience listener Rachel started wondering whether her cat Eva could fend for herself while watching her uncoordinated swipes at a toy on a string, and seeing her fall off the sofa. Even though Eva was once a stray, she now lives entirely indoors, and it is hard to imagine her holding her own back on the mean streets. But could this pampered pet recover her survival instincts? Or would she go hungry, or fall foul of other cats or predators? Cat behaviour expert Roger Tabor is on hand with answers. His pioneering ‘cat-navs’ shine a light on what cats get up to inside and outside the home; we meet one of his subjects, a tiny cat with a fierce personality. Roger explains how a cat’s survival toolkit depends on their sex, breed, and above all their early life. Environment matters, too, so in Japan, where Rachel and her pet cat live, we visit a cat shelter to learn about the day-to-day challenges stray cats face.And just how ‘domestic’ are our cats, anyway? How different are they from their wildcat cousins, and how did they come to be our companions in the first place? It turns out beguiling humans might be even more of a survival trick than hunting.Presenter: Melanie Brown Producer: Cathy EdwardsContributors: Roger Tabor – Chartered Biologist and Cat Behaviourist Jamie Baker – Head Keeper, Battersea Park Children’s Zoo Dr Eva-Maria Geigl – Research Director, CNRS (French National Centre for Scientific Research) Susan Roberts and Cheryl Nodhturft-Mori – Japan Cat Network(Image: Cat in Lion costume. Credit: Getty Images)

Concrete is the most widely used substance on earth after water. It’s quite literally the foundation of the modern world, and no wonder - it’s strong, cheap, and mouldable into nearly any shape.But these benefits come at a cost: concrete production is responsible for around 8% of global CO2 emissions - that’s around three times more than the aviation industry. Concrete might not look pretty, but given its carbon footprint, should we be more careful about how we use it? And rather than throwing waste into landfill, could we recycle it instead? That’s what Crowdscience listener Catherine wants to know.To investigate, Marnie Chesterton and Anand Jagatia learn more about what makes concrete such a brilliant and versatile material. It’s down to the chemistry of how cement dries – which, it turns out, is anything but boring. They find out how the stuff is made, and why that produces so much carbon. And they hear about some ingenious projects to repurpose demolition waste – including creating underwater habitats for marine life, and using 3D printers to turn crushed concrete into street furniture. With Prof John Provis, Prof Becky Lunn, Chris LaPorta, Sheryl Lee, Dr Edward Randviir and David LacyPresented by Marnie Chesterton and Anand Jagatia. Produced by Anand Jagatia for BBC World Service[Image: Discarded Concrete, Credit: Getty Images]

The science is unequivocal: human-made climate change is leading the world into an environmental crisis, and time is running out to prevent permanent damage to ecosystems and make the planet uninhabitable for many of us humans. As communities around the world increasingly experience the devastating effects of global warming, world leaders, policy makers and scientists from all over the globe are attending COP26, the United Nation’s major climate summit in Glasgow, Scotland. Each nation will be frantically negotiating its commitments to tackling emissions - many agree it’s a pivotal moment for the future of humanity.Crowdscience hosts a panel of three experts taking part in the conference, to hear their thoughts on what progress has been made so far. They answer listener questions on rising sea levels, explaining that a temperature rise of more than 1.5 degrees won’t just affect small island nations but will have serious consequences for every country in the world. We hear about an interactive atlas developed by the Intergovernmental Panel on Climate Change (IPCC) that shows the impact of higher temperatures in different regions. And presenter Marnie Chesterton asks about the financial barriers that have prevented many people from traveling to COP26 and discovers why it’s vital that people from the global south have their voices heard. Featuring:Ko Barrett, Vice-chair of the Intergovernmental Panel on Climate Change (IPCC) Dr Saleemul Huq, Director of the International Centre for Climate Change and Development in Bangladesh(ICCCAD) Dr Tara Shine, Director of Change By DegreesProduced by Melanie Brown and Marijke Peters for BBC World Service.[Image: Delegates in the Action Zone at COP26 UN Climate Summit, Glasgow. Credit: Getty Images]

As the world slowly moves away from using fossil fuels for electricity, one tiny Scottish island has proved it’s possible to rely almost entirely on renewables.The inner Hebridean isle of Eigg used to get its power from diesel generators. But in 2008 its residents launched the world’s first electricity system powered by nature, and the Crowdscience team wants to know exactly how they did it, and whether such a model could work in other places with no national grid? Marnie discovers that the community is key to the success of this project, meeting the maintenance men who taught themselves to install equipment and solve any problems themselves, and hearing from residents who’ve changed their habits to use less juice. With the mainland more than an hour away by a once-daily ferry, this kind of resourcefulness is vital. Hydroelectric generators harness the power of running water and are complemented by wind turbines and solar panels on peoples roofs, meeting 95% of Eigg’s energy needs. Now others are learning from this unique experiment and we meet the Malawians who were inspired after visiting Eigg. A solar grid in the village of Sitolo has provided power to thousands of people, and the people who designed it are planning others.Thanks to Eigg residents: Sue Hollands, Maggie Fyfe, Eddie Scott, Bob Wallace, Greg CarrPresented by Marnie Chesterton Produced by Marijke Peters for BBC World Service.This episode of CrowdScience has been edited to correct a factual errorImage: Wind turbines on Eigg Credit: Getty Images

"To be or not to be” was never your decision. No one alive today is an “exister” by consent - your parents made that call for you. But who can blame them? Animals are hardwired with strong impulses towards their procreative goals, and we humans, by and large, are no different. But for some conscientious people alive today, this most fundamental of biological impulses is butting up against a rational pessimism about the future...With apocalyptic scenes of natural disasters, rising sea levels and global pandemics causing existential dread and actual suffering, it's understandable that CrowdScience listener Philine Hoven from Austria wrote to us asking for help her make sense of what she sees as the most difficult question she faces - should she have children?In this episode, presenter Geoff Marsh helps Philine to predict what kind of a world her hypothetical child might inhabit, and explores the impact their existence, or indeed non-existence might have on society and the planet. Plus, we'll explore what ‘antinatalism’- a philosophical stance which argues against procreation, can tell us about the moral landscape of the unborn. With Ms Caroline Hickman, Professor Mike Berners-Lee, Professor Noriko Tsuya and Professor David Benatar.Presented and produced by Geoff Marsh for BBC World Service

Philosophers have long pondered the concept of a brain in a jar, hooked up to a simulated world. Though this has largely remained a thought experiment, CrowdScience listener JP wants to know if it might become reality in the not-too-distant future, with advances in stem cell research.In the two decades since stem cell research began, scientists have learned how to use these cells to create the myriad of cell types in our bodies, including those in our brains, offering researchers ways to study neurological injuries and neurodegenerative disorders. Some labs have actually started 3D printing stem cells into sections of brain tissue in order to study specific interactions in the brain. Human brain organoids offer another way to study brain development and diseases from autism to the Zika virus.So, might stem cell research one day lead to a fully-grown human brain, or is that resolutely in the realm of science fiction? If something resembling our brains is on the horizon, is there any chance that it could actually become conscious? And how would we even know if it was?Host Marnie Chesterton takes a peek inside the human brain and speaks with leading scientists in the field, including a philosopher and ethicist who talks about the benefits – and potential pitfalls – of growing human brain models. Along the way, we'll pull apart the science from what still remains (at least for now) fiction.Presented by Marnie Chesterton Produced by Sam Baker for BBC World Service Assistant Producer: Jonathan Blackwell

Snails are a major enemy of gardeners around the world, invading vegetable patches and gobbling prize plants. CrowdScience listener Alexandre reckons he’s removed thousands of them from his garden, which got him wondering: apart from eating his garden to the core, what’s their wider role in nature? Would anyone or anything miss them if they suddenly disappeared?And for that matter, what about other creatures? We all know how complex biodiversity is, but it seems that some animals are more important than others in maintaining the balance of life on earth. Is there anything that could go extinct without having knock-on effects?CrowdScience heads to the Hawaiian mountains, a snail diversity hotspot, to discover the deep value of snails to native ecosystems there. Researchers and conservationists are working together to protect these highly endangered snails, and their natural habitats, from multiple threats. We hear why all snails – even the ones munching Alexandre’s petunias – have their role to play in the natural world, and get to grips with cascading extinctions: how the loss of a single species can trigger unpredictable effects on a whole ecosystem.With contributions from Imogen Cavadino, Dr Norine Yeung, Dr Kenneth Hayes, Dr David Sischo, Jan Kealoha, and Professor Ian Donohue.Presented by Marnie Chesterton Produced by Cathy Edwards for the BBC World Service[Image credit: Getty Images]

In the past 18 months we have heard lots about the human immune system, as we all learn about how our bodies fight off Covid-19 and how the vaccine helps protect us. But this got listener John, in Alberta, Canada, thinking about how trees and plants respond to diseases and threats. Do they have immune systems and if so, how do they work? Do they have memories that mean they can remember diseases or stressful events 5 months, or 5 years down the line, to be better prepared if they encounter the same threats again?Presenter Marnie Chesterton sets out to investigate the inner workings of plants and trees, discovering that plants not only have a sophisticated immune system, but that they can use that immune system to warn their neighbours of an attack. Some researchers are also investigating how we can help plants, especially crops, have better immune systems – whether that’s by vaccination or by editing their genes to make their immune systems more efficient. But some plants, like trees, live for a really long time. How long can they remember any attacks for? Can they pass any of those memories on to their offspring? Crowdscience visits one experimental forest where they are simulating the future CO2 levels of 2050 to understand how trees will react to climate change. Featuring: Professor Jurriaan Ton, University of Sheffield Professor Xinnian Dong, Duke University Dr Estrella Luna-Diez, University of Birmingham Peter Miles, F.A.C.E. Facility Technician, University of BirminghamPresented by Marnie Chesterton and Produced by Hannah Fisher for the BBC World Service.Photo credit: Getty Images

This year has been a weird one for UK gardeners – unpredictable spring temperatures meant flowers failed to bloom and throughout the rainy summer, slugs have been savaging salad crops. But why and when plants blossom is about more than just early cold spells and wet weather, and a listener in California has asked Crowdscience to investigate. Flowering is vital to both plants and us. Without it, they wouldn’t be able to evolve and survive (and we wouldn’t have anything to eat). Anand Jagatia hears that different species have developed different strategies for doing this based on all sorts of things, from where they’re located to how big they are to what kind of insects are around to pollinate them. The famously stinky Titan Arum, or corpse flower, for example, blooms for a single day once every decade or so before collapsing on itself and becoming dormant again. This gives it the best chance of attracting carrion beetles in the steamy Sumatran jungle. But other plants open their petals much more regularly, which is a process regulated by a clever internal clock that can sense daylight and night. It’s even possible to trick some of them into producing flowers out of season. Cold is also a vital step for some brassicas and trees, and scientists are starting to understand the genes involved. But as climate change makes winters in parts of the world warmer and shorter, there are worrying knock on effects for our food supply.Produced by Marijke Peters for BBC World Service.Featuring: Guy Barter, RHS Professor Judy Jernstedt, UC Davis Professor Dame Caroline Dean, John Innes Centre Professor Ove Nilsson, Umea Plant Science Centre(Photo credit: Getty Images)

Look into my eyes. What do you see? Pupil, lens, retina… an intricate set of special tissues and mechanisms all working seamlessly together, so that I can see the world around me. Charles Darwin called the eye an ‘organ of extreme perfection’ and he’s not wrong!But if the eye is so complex and intricate, how did it evolve? One listener, Aloyce from Tanzania, got in touch to pose this difficult question. It’s a question that taxed Darwin himself, but CrowdScience is always up for a challenge!The problem is that eyes weren’t ever designed - they were cobbled together over millions and millions of years, formed gradually by the tweaks and adaptations of evolution. How do you get from the basic detection of light to the wonderful complexity - and diversity – of visual systems we find throughout the animal kingdom?CrowdScience sent Marnie Chesterton on an 800 million year journey to trace how the different elements that make up the human eye gradually came into being; from the emergence of the first light-sensitive proteins to crude eye-cups, from deep sea creatures with simple pinhole eyes to the first light-focusing lenses, all the way to the technicolour detail of the present day.Produced by Ilan Goodman for the BBC World Service.With contributions from: Dr Adam Rutherford, Dr Megan Porter, Professor Dan Nilsson, Dr Samantha Strong(Photo Credit: Getty Images)

Pioneering physicist and inventor Nikolas Tesla dreamt of connecting the world up through wireless communication and power. Despite demonstrating he could transfer power short distances his longer distance experiments were considerably less successful. But CrowdScience listener, George from Ghana, wants to know if now - more than one hundred years after Tesla’s demonstrations - his dream of wireless power is closer to becoming a reality.In countries where rugged landscapes make laying traditional power lines difficult and costly, could wireless electricity help connect those communities who are without mains power?CrowdScience presenter Melanie Brown beams to reporters around the world who visit scientists now using state of the art technology to reimagine Tesla’s dream. Alex Lathbridge is in Ghana and after meeting listener George he gently doorsteps a local electrical engineering lecturer to find out how electricity can ‘jump’ between two coils.Reporter Stacy Knott visits start-up company EMROD in New Zealand who are developing ‘beamable’ electricity. She hears an electric guitar being powered from 36 metres away with no wires and finds out how they are using lasers to make sure they don’t harm any wildlife that might wander into the beam. We then hear how wireless electricity could help fulfil the power demands of a growing electric vehicle market. Reporter John Ryan visits the town of Wenatchee where it has been electrifying its’ bus fleet and putting wireless chargers into the tarmac at bus-stops so that the busses can trickle charge as passengers get on and off. Finally, we ask whether one day, the tangled knot of wires spilling out of our electronic devices will be but a thing of the past. Presented and Produced by Melanie Brown with additional reporting from; Alex Lathbridge, John Ryan and Stacey KnottWith contributions from; Prof. Bernard Carlson, Dr Samuel Afoakwa, Ray Simkin, Greg Kushnier, Andy Daga and Richard DeRock(Photo credit: Getty Images)

Our connection to the night sky spans cultures and millennia: observing the stars and planets helped our ancestors navigate the world, tell stories about the constellations, and understand our place in the universe. But these days, for the vast majority of us, seeing the stars is getting harder. 80% of people live under light polluted skies, and in many cities you’re lucky to see a handful of stars at night.This state of affairs is bothering CrowdScience listener and keen stargazer Mo from Salt Lake City in the USA, who wonders if there’s anything we can do about light pollution. Of course, we could simply turn out all the lights, but that’s unrealistic. So what are smarter ways of lighting our communities to preserve our view of the cosmos?Increasingly worried by the effect of artificial lighting on the ability to observe stars, astronomer Dr Jason Pun set up a series of monitoring stations to continuously measure ‘sky glow’. By comparing sky glow across the world, he wants to figure out which approaches work best.One community taking an active approach is the South Downs National Park in South East England, one of a number of Dark Sky Reserves around the word. We visit the park and speak to the Dark Skies Officer there, to find out how people are coming together to turn down their lights and keep the night dark.And it’s not just stargazing that’s threatened by light pollution. Artificial light at night disrupts the circadian rhythms of wildlife. We visit a project in rural Germany looking into the benefits of dark-sky-friendly lighting on insect populations there.With contributions from Dr Jason Pun, Paulina Villalobos, Dan Oakley, Doug Jones, Dr Sibylle Schroer and Sophia Dehn.Presented by Anand Jagatia with additional reporting by Felix FranzProduced by Cathy Edwards[Image credit: Getty Images]

How we sleep is a topic of endless fascination and for some can, ironically be quite exhausting. Modern life has allowed us to invade the night, and those pesky late night work emails, social media and TV all conspire to limit our sleep or simply prevent us from a truly restful night. But if we travel back in time, did our ancestors master sleep any better? No air-con or electric fan for them on hot humid nights, and only smoky fires to keep them warm on cold, snowy nights. What if we go way back into our pre-history, to our ancient human ancestors? No interruption for them from an unwanted work email, however perhaps a ravenous lion gave them more reason for those night time worries. CrowdScience listener Tom asks our sleep deprived presenter Datshiane Navanayagam to investigate how our sleep has changed over history and pre-history. She talks to Professor Russell Foster, Head of the Sleep and Circadian Neuroscience Institute at the University of Oxford and Neanderthal expert Dr Rebecca Wragg Sykes about slumber habits in days of yore, and in doing so, she uncovers some top tips from our ancestors that may give us all a better nights rest.Presented by Datshiane Navanayagam and Produced by Alexandra Feachem(Woman sitting in bed and yawning. Credit: JGI/Jamie Grill/Getty Images)

If you’ve ever fallen over and grazed your skin, maybe you wished it were made of stronger stuff. The tough hide of a rhinoceros or the protective armour of a stag beetle would do a better job. It’s a thought that’s been bothering CrowdScience listener Paul, who points out that our skin also suffers from acne, eczema and hives; it dries out; it bruises. In fact, human hide is so vulnerable that we cover our feet in other animals’ skin and our bodies in clothes just to make life more comfortable. Is this really the pinnacle of evolution? Marnie Chesterton makes the case for the largest, fastest-growing organ, hiding in plain site on our body. Tissue Engineer Professor Sheila MacNeil from Sheffield University explains how skin manages to be breathable yet waterproof; flexible yet stronger than steel; sensitive to touch but protective against pollution and damaging UV. Skin biologist Dr Christina Philippeos from King’s College London explains how our bodies make a scar. Professor Muzlifah Haniffa has developed an atlas of the human skin – a tool to help researchers unravel the mysteries of how different skin cells interact. This atlas should help treat skin diseases in the future. Over in Tanzania’s Regional Dermatology Training Centre in Moshi, Dr Daudi Mavura talks us through a rare but devastating skin disorder called Xeroderma Pigmentosum, or XP. For children with XP, sunlight is dangerous because a mutation in the skin’s DNA repair mechanism means that UV rays can cause lesions and tumours.Our epidermis is already multifunctional but over at Ben May Department of Cancer Research at the University of Chicago, Professor Xaioyang Wu and colleagues are looking at how much more skin could do. Personalised skin grafts may provide living drug patches to help people manage their disease, addiction or even weight. With thanks to Dr Lynne MacTavish from Mankwe Wildlife Reserve in South Africa for describing a rhino’s skin.Produced and presented by Marnie Chesterton.[Image: Young and Old, dry skin Credit: Eric A. Nelson/Getty Images]

Humans are responsible for emitting over 40 billion tonnes of carbon dioxide into the atmosphere every year – and we all know that we need to reduce that figure to prevent devastating climate change. Listener Saugat wonders whether smart technology and artificial intelligence can help us do this more quickly?Green energy will go a long way to tackling the problem, but integrating wind and solar into our current electricity grid is complicated. CrowdScience hears how AI is being used at a wind farm on the island of Orkney to predict periods of high winds, so that excess energy can be turned into hydrogen and stored, then converted back to electricity when there’s greater demand.Digital mirrors are also playing a major role in optimising performance, and scientists say cloud-based “twins” of physical assets like turbines can improve yield by up to 20%, allowing engineers to identify problems via computer without ever having to be on site.Marnie visits an intelligent building in London’s financial district where sensors control everything from air-conditioning to lighting, and machine learning means the building knows which staff will be on which floor at any given time, switching off lifts that are not in use and adjusting ventilation to save on power. Its designer says incorporating this kind of digital technology will help companies achieve net zero more quickly. And in India, more than half the population are involved in agriculture, but the sector is plagued by inefficiency and waste. Tech start-ups have realised there’s potential for growth, and are using drones to monitor crop production and spraying, giving farmers apps which help them decide when and where to fertilise their fields. Produced by Marijke Peters for BBC World Service.Featuring:Professor Srinivasan Keshav, University of CambridgeMatthew Marson, Arcadis Group [Image Credit: Getty Images]

Today, up to 3 billion people around the world play video games, from candy based mobile puzzles to virtual battlegrounds filled with weapons. Many people have turned to gaming during the pandemic as a way of staying connected – but what does science really say about the impact of gaming? Does playing violent video games lead to violence in the real world? Do brain training apps really work? How much gaming is too much – can videogames really be addictive? And how can videogames help us to explore difficult issues like death, grief and loss?Alex Lathbridge and Anand Jagatia look at the evidence and play some games along the way, speaking to psychologists, doctors and game designers about the power of video games to change us - for better or worse.With Adrian Hon, Professor Andrew Przybylski, Professor Pete Etchells, Professor Henrietta Bowden-Jones and Dr Sabine Harrer

Reduce, Reuse, Recycle. It’s a well-known phrase that we all try and follow in our day to day lives. But are our current recycling habits the best they can be? It’s a hot topic at Crowdscience - multiple listeners have contacted Crowdscience with questions about the ins and outs of recycling. We follow one listener’s food waste to a processing plant to investigate whether or not it could be processed in our own homes. But aside from the food waste, what about the containers it comes in? We investigate if food containers really need to be cleaned before we put them in recycling bins, or if that just wastes water.Recycling processes differ all over the world, so we hear from reporter Chhavi Sachdev in Mumbai, India, who follows her plastic waste to find out how plastic sorting and recycling is a whole economy of its own.But new technologies have meant that biodegradable and bioderived plastics are starting to appear in our packaging, and one Crowdscience listener wants to know which is better for the environment – traditional plastic that has been recycled, or bioplastic and compostable alternatives? And looking to the future, could we ever recycle our plastic waste at home and use 3D printers to make useful things out of our own waste?Marnie Chesterton delves into these questions with Circular Economy Project Manager Dr Rhiannon Hunt of Manchester Metropolitan University, to discover the details of recycling and unearth how we can make our own recycling as efficient as possible. With Dave Atkins, reporter Chhavi Sachdev and Dr Rhiannon Hunt. Presented by Marnie Chesterton and Produced by Hannah Fisher for the BBC World Service.[Image credit; Getty Images]

One CrowdScience listener finds herself unconcerned about much of the world’s problems, it leaves her wondering: am I a psychopath?Inspired by a previous episode on empathy, this listener asked is it true that psychopaths don’t empathise and what are the character traits of psychopathy? Marnie Chesterton talks with a diagnosed pro-social psychopath to find out. She also pays a visit to the Netherlands Institute for Neuroscience and gets into an MRI scanner to discover what is happening in her brain when she empathises.Studies suggest around 1 percent of the general population exhibit traits associated with psychopathy and that rises to 3-4 percent in the world of business. But is this really the case?Why is there so much stigma associated with psychopathy and do psychopaths even exist or is it just a convenient term to label those whose emotional range sits outside of the “norm”? Presented by Marnie Chesterton and produced by Caroline Steel for the BBC World Service.Guests: Julia Shaw Jim Fallon Valeria Gazzola Kalliopi Ioumpa[Image credit: Getty Images]

Anyone who has ever taken the Christmas lights out of the cupboard, only to discover they’re hopelessly tangled, will sympathise with this week’s listener Eric. He has a 45m garden hose that always seems to snarl up and snag when he waters his garden, and he wonders what he’s doing wrong? Marnie starts by discovering the important difference between tangles and knots, as she scales a cliff with an experienced climber who explains the way you tie rope is a matter of life and death. Physicists are also fascinated in how string becomes jumbled up and one man has even won an IgNobel award for his work in this field. Doug E Smith discovered that if you put a piece of string in a box then spin it around, its length, thickness and how long you shake the box for, all determine whether it will tie itself up. Not only that, the more the string becomes twisted, the more likely it is to cross over itself and become impossible to untangle.While tangles might be annoying in hair or cables, they’re also a fundamental part of human life. Our DNA is constantly folding itself to fit inside tiny spaces – there are two metres of the stuff inside every cell, where it’s packed down tightly, before it must untangle and duplicate for those cells to divide. It does this with the help of specific enzymes, and when the process goes wrong it leads to cell death. But scientists are also studying molecular tangles that might benefit us humans, and creating nano-sized knots that can be turned into nets or meshes with incredible properties. Producer: Ilan Goodman Presenter: Marnie Chesterton

Standing takes less energy than walking, so why does it feel more tiring? At least, it does for CrowdScience listener Nina. She can march for hours without getting tired, but her legs and feet get achy after just a short time standing still.It’s one of three walking-themed questions CrowdScience is tackling this week. Taking inspiration from our active listeners, Marnie Chesterton walks up a hill with Caroline Williams, author of a new book about why humans are designed to move. We find out how our whole system – body and brain – works better when we’re walking, compared to standing still. We’re probably set up this way because of our evolutionary history: hunting and gathering needed us to be ‘cognitively engaged endurance athletes’.We stop for a break.. but is it true that we shouldn’t sit down to rest during a walk? Our listener Sarah is a keen hillwalker but likes to take the weight off her feet every now and again. Her hillwalking friends disapprove, saying she should rest on her feet. Is this a myth CrowdScience can bust?And finally a question from listener Matteo: is walking or running better for your health? Numerous studies show significant benefits to both forms of exercise, but in the end, the best kind of exercise is the one you’re motivated to do.With Caroline Williams, Dr François-Xavier Li, Professor Dick Greene and Professor Duck-Chul Lee.

Food. For all of us it is a basic necessity and for those lucky enough, it is something we spend a lot of time planning and enjoying. CrowdScience listeners certainly have a lot of food related questions; in this buffet of an episode Marnie Chesterton opens the fridge door to pick the tastiest. Starting with the seemingly simple question of what makes us feel hungry, and ending in outer-space, Marnie investigates flavour, nutrition and digestion. After a year when watching TV has become a core activity for many people stuck in their homes, one listener wants us to find out if eating food whilst watching the TV affects our perception of taste. We then journey to the skies and ask if it is true that food tastes blander on aeroplanes, what does that mean for astronauts’ mealtimes? Back on earth, Marnie explores whether humans are the only animals that season their food.Tuck in your napkins and prepare to feast on a smorgasbord of scientific snacks. Presented by Marnie Chesterton and Produced by Melanie Brown and Hannah Fisher for the BBC World Service. Guests: Professor Charles Spence Dr Kristine Beaulieu Mr. Takashi Funahashi Ruben Meerman Chef Jozef Youseff

It took a while before it was officially recognised as a major symptom of Covid-19, but loss of smell has affected up to 60 percent of people who have had the virus. And for a significant portion, smell continues to be an issue for weeks or months after their recovery. So what’s going on and how can you get your sense of smell back? We tend to think of our sense of smell as something universal – if it smells bad to me, it probably does to you but that is not the case for CrowdScience listener Annabel, who wonders why things other people love to sniff, she finds disgusting. Anand Jagatia investigates the science of smell, gets up close to the world’s smelliest plant and finds out if smell training can help those with long-term issues after Covid. Contributors Ellie Byondin, supervisor of the Princess of Wales Conservatory at London’s Kew Gardens Thomas Hummel, University of Dresden Carl Philpott, from the UK’s Norwich Medical School Sissel Tolaas, artist and smell historian based in Berlin Noam Sobel, Weizmann institute of sciencePresented by Anand Jagatia and Produced by Marijke Peters for the BBC World Service

Scales don’t come planet-sized, so answering a question from David in Ghana may require some ingenuity, after all, calculating the weight of the Earth is a huge task. Using a set of weighing scales and a 400 year-old equation, Marnie Chesterton attempts to find out just how much the Earth weighs and is it getting heavier or lighter over time? But how would a planet gain or lose mass? Which tips the scales: meteorites falling from space or gases constantly escaping from our atmosphere? And does the answer have any implications for the future of Earth? Could the atmosphere eventually run out? Contributors: Anuradha TK, former project director at ISRO Matt Genge, geologist at Imperial College London Jon Larsen, researcher at the University of Oslo Anjali Tripathi, astrophysicist Ethan Seigel, journalist and astrophysicistPresented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service.[Image: Earth on scales. Credit: Getty Images]

They say life is sweet. Well that’s certainly the case for CrowdScience listener Trevor in Poland who wonders why he can’t stop reaching for the cookie jar. He grew up drinking fruit juice with added sugar but wonders whether his genes could be as important as his environment when it comes to his sweet tooth, especially since his wife seem to be satisfied with mainly savoury snacks. The World Health Organisation says added sugar should constitute a maximum of 5% of our daily energy intake because it can contribute to diabetes, heart disease and obesity. But that’s tricky when you consider it’s now in everything from salad dressings, to savoury sauces.Manufacturers have been promoting sugar alternatives for decades but recreating the unique taste and feel of it in the mouth are a challenge. Marnie Chesterton gets to try a brand new innovation – a so-called ‘rare’ sugar that has 70 percent of the sweetness but almost none of the calories. In nature, allulose is found in figs, but one producer has discovered a way to make it in the lab. Does it taste as good as it claims? Whilst switching to alternative sugars and sweeteners may reduce the calories, some researchers claim that tasting sweetness, wherever it comes from, can disrupt the body’s mechanism for regulating blood-sugar levels, increasing the risk for conditions like diabetes.Presented by Marnie Chesterton and produced by Marijke Peters for the BBC World Service

It's a topic that's taboo in many cultures, yet it's also something nearly every woman experiences – on average upwards of 400 times throughout her life: menstruation. Responding to a flood of questions from our CrowdScience listeners, Marnie Chesterton seeks to unpack how periods affect women physically, mentally and societally. Why did humans evolve to have periods when fewer than two percent of mammals share our experience of menstrual cycles? Is it really a good use of our limited energy reserves? What can the little Egyptian spiny mouse teach us about PMS symptoms? We hear why periods may reduce the number of faulty embryos that implant and how more menstrual cycles may even increase our chances of developing certain types of cancer. Finally, as the number of periods a woman has over the course of her life has more than quadrupled since the pre-industrial era, Marnie asks: Do we really still need to have them? Contributors: Dr Nadia Bellofiore, Hudson Institute of Medical Research at Monash University Dr Deena Emera, Buck Institute Lameck Kiula, Jambo for Development Sally King, Menstrual Matters & King's College London Dr Diana Mansour, New Croft Centre & Newcastle UniversityPresented by Marnie Chesterton Produced by Sam Baker and Melanie Brown for the BBC World Service

As millions more of us move to live in densely populated cities, we almost inevitably face living in closer proximity to our neighbours. Neighbour noise can certainly be a source of annoyance – but could it even be damaging to our health? Increasing evidence suggests that unwanted noise can cause sleep deprivation, distraction and annoyance, as presenter Anand Jagatia finds out. He discovers that noise annoyance has a small but significant impact on our wider health – including our cardiovascular system – but that annoyance is not necessarily down to sound alone. Factors such as perception of the neighbourhood and relationships with our neighbours also play a part. CrowdScience has examined living with unwanted noises before, and we revisit our trip to the acoustics lab at the University of Salford in Manchester, UK. Here, we meet the researchers and engineers investigating the best ways to make our homes more pleasant for our ears whilst still maintaining the ‘buzz’ of city life. Contributors:Contributors: Professor Charlotte Clark, St George’s University of London Professor Trevor Cox, University of Salford Manchester Professor Bill Davies, University of Salford Manchester Dr Mags Adams, University of Central Lancashire (formerly University of Salford Manchester, at time of recording)Produced by Jen Whyntie and presented by Anand Jagatia for the BBC World Service.

You are a star. Literally. You are a carbon-based life form and those atoms of carbon in the molecules that make up your cells were formed by a nuclear fusion reaction at the heart of long dead stars. That goes for the oxygen in your lungs too. And the red blood cells that carry that oxygen to your tissues? They contain haemoglobin, and nestled at the heart of each molecule is an element (iron) formed by a supernova - the fiery explosion at the death of a star. Your body is a walking, thinking museum of some of the most violent events in the universe. This, as CrowdScience host Marnie Chesterton discovers, isn’t as special as it sounds. All of the stuff on the earth - the elements that make clouds and mountains and mobile phones – they all have an origin story. CrowdScience tells that story, starting with the big bang and ending with physicists, creating new elements in the lab. Find out the age of the elements and the distance they have travelled to make their current home on earth. Interviewees: Dr Dorota Grabowska, Professor Andrea Sella, Dr Chris Pearson, Dr Jacklyn Gates (Photo: Neutron star. Credit: Getty Images)

There are over 400,000 species of plant on earth, they’re on every continent including Antarctica. But humans only regularly eat about 200 species globally, with the vast majority of our nutrition coming from just three species. Many of the fruits, leaves and tubers that other plants grow are packed full of toxins that are poisonous to us, and would make us very ill if we ate them. But could we take out the poisons and create new, edible crops? That’s what CrowdScience listener Marija wants to know.Crowdscience dives into this topic, and uncovers the that many crops are poisonous, and why so few plants are eaten globally. Host Anand Jagatia finds that even the modern scientific processes of crop breeding are very slow. But science can now engineer plants at the genetic level by adding, silencing or removing specific genes. This ‘genetic modification’ is hugely controversial but can be highly effective. Anand finds a man who has spent decades making cotton seeds edible by removing the poisons they naturally produce in their seeds. This GM crop could help fend-off starvation. But sometimes introducing poisons can be as important as removing them, as we find in the genetically modified ‘BT eggplants’ in Bangladesh. The new gene makes the vegetable toxic to a major insect pest, so they are much easier to grow. But GM crops are not the perfect solution. They have problems of gene escape, can increase the use of environmentally damaging herbicide, and can be open to monopolisation. In some countries, particularly in Europe, GM crops are hugely controversial. Anand finds out whether these concerns stand up to science and looks at the counterpoint in developing countries in Africa, South Asia and elsewhere, where local farmers like Patience Koku in Nigeria have little time for some of the concerns around GM, particularly as they see poor harvests, poverty and starvation as the more pressing problems. Contributors: Professor Sandra Knapp, The Natural History Museum in London Professor Julie King, Nottingham University Professor Keerti Rathore, Texas A&M University Dr Yousuf Akhond, Bangladesh Agricultural Research Institute Professor Matthew Cobb, University of Manchester Patience Koku, Nigerian Farmer and member of the Global Farmer’s Network Alliance for Science Produced by Rory Galloway and presented by Anand Jagatia for the BBC World Service.Image: Farmer with Fruits. Credit: Arif Hossain, Farming Future Bangladesh.

Have you taken classes to learn a new sport or musical instrument or a language? It’s hard work! Why is it that as children we effortlessly absorb new skills and we don’t as adults? That’s what 50-something listener Gary Grief wondered about playing guitar. Do you need to play more frequently as an adult to attain the same level of expertise? Does the 10,000-hours theory still apply? Presenter and budding tabla-player Anand Jagatia embarks on a musical journey to discover what neuroscience can tell us about muscle memory and learning. Do musicians and sportsmen share the same challenges? By understanding what’s happening in the brain, can we learn how to learn better? With tabla-teacher Satvinder Sehmbey, neuroscientist Dr Jessica Grahn, viola-player Dr Molly Gebrian and sports scientist Prof Yannis Pitsiladis. Presented by Anand Jagatia Produced by Dom Byrne for the BBC World Service[Image: Adult and Child learning Piano. Credit: Getty Images]

When eating a blackberry one day, CrowdScience listener Charles got a tiny seed stuck in his teeth. That got him wondering: why are seeds the size they are? Why does a blackberry have dozens of tiny pips, while a peach has one huge stone right in the middle?Plant seeds have been around for hundreds of millions of years, so they’ve had plenty of time to shapeshift into wildly different forms: from dust-like orchid seeds to giant coconuts. This evolution has been a long and intricate dance with wind, water and animals; we ask how different kinds of seeds might respond to today’s environmental threats and rapidly changing ecosystems.And we go in search of the world’s biggest seed, the coco de mer: native to just two remote islands in the Indian Ocean and weighing up to 18kg, how did this seed evolve to be so much bigger than any other? With Professor Angela Moles, Dr Si-Chong Chen, Marc Jean-Baptiste, Dr Frauke Fleischer-Dogley and Dr Wolfgang Stuppy.Presented by Marnie Chesterton Produced by Cathy Edwards for the BBC World Service[Photo: Different sized fruit seeds. Credit: Getty Images]

Most of us don’t like to dwell on our toilet habits, but this week Crowdscience has gone down the drain to discover what wastewater can tell us about our health.It’s been more than a year since scientists across the globe started to track the spread of Covid-19, with help from home test results and hospital data. Marnie Chesterton investigates the latest tool in their arsenal: sewage. Listener Kevin has heard how human waste can be monitored to check for virus levels, and wants to know if it can also be used to stop the disease in its tracks? Although the coronavirus has been discovered in people’s poo, so far there’s little indication it’s actually being spread through the water system. But by taking regular samples from different parts of cities, authorities are now able to accurately predict a local peak weeks before the population shows signs of sickness, then take immediate measures to alert them. In Detroit we hear how environmental engineer Professor Irene Xagoraraki used this method to detect a rare strain of Herpes which doctors didn’t even know was a potential problem. Marnie also talks to Professor Nick Thomson from the Wellcome Sanger Institute, who sequenced the genome of the bacteria that causes cholera, to understand how it has crisscrossed the globe. He discovered that the pandemic currently devastating Yemen actually originated in Asia. It’s a discovery that has changed how the WHO is thinking about this killer disease and could have important implications for vaccination programmes. But our effluent can also pose environmental problems, and Professor Andrew Johnson from the UK’s Centre for Ecology and Hydrology explains there are now as many as 300,000 chemicals that could threaten natural habitats. While authorities try to test each one individually, he’s concerned they may have different effects when they mix in wastewater, and current monitoring systems don’t take this into account. Not only that, but some of these substances contain silver nanoparticles, which Professor Juliane Filser tells us stick around in soil for ever, threatening organisms and bacteria at the base of the food chain. Presented by Marnie Chesterton and Produced by Marijke Peters for the BBC World Service.[Image: Sewage outlets. Credit: Getty Images]

Grief is universal. It is something almost all of us will go through at some point. And it is something that the people we love will experience when we die.Grief can be all consuming, it can make everyday tasks like getting out of bed, feel impossible. Which makes listener Oliver from Australia wonder - what is the point? It doesn’t bring what we lost, back.Why have we evolved to be so affected by loss? Be it the death of a loved one, the end of a relationship or the loss of a job. Does it serve any purpose? Or perhaps it is just the price we pay for being a social species with such strong connections.Image: Families Mourn Victims of The Tamaulipas Massacre in Tuilelén, Guatemala Photo by Josue Decavele/Getty ImagesProduced by Caroline Steel and presented by Marnie Chesterton for BBC World Service.

Gossip often has negative connotations, but does it get a bad rap? Might it serve a useful function and should we think of gossiping as an advanced social skill rather than a personality defect? CrowdScience listener Jayogi thinks it might be useful, and has asked CrowdScience to dig into the reasons why we find it so hard to resist salacious stories.Presenter Datshiane Navanayagam meets a scientist who views gossip as a key evolutionary adaption - as humans started to live in bigger cooperative groups, gossiping was a way of bonding and establishing acceptable group behaviour as well as cementing reputations of trustworthiness.Datshiane heads to the local park to catch some real gossiping in action and finds out that whilst people like to gossip they don’t consider themselves gossipers. Datshi asks a team of scientists what information we are most keen to share and glean in these interactions and if there is such a thing as ‘good’ and ‘bad’ gossip. She hears that in some group settings – like in the workplace - gossip can enhance cooperation and limit free-riders, but that it can also have a more self-serving dark side. Datshiane finds out if our stone-age gossipy minds are fit to operate in the world of mass communication and social media – is our fixation on celebrities related to our being hard wired to gossip?Presenter: Datshiane Navanayagam Producer: Melanie Brown[Image: Gossiping people. Credit: Getty Images]

If a tree falls in a forest, and no-one is there to hear it, does it make a sound? This is an age-old debate that listener Richard and his family have been arguing about for years. Can CrowdScience settle it once and for all? Caroline Steel speaks to experts in hearing, biology, philosophy, physics and sound design, which takes her to some unexpected places.Professor Stefan Bleek is an expert in psychoacoustics who says that sounds only exist in our heads. Dr Eleanor Knox and Dr Bryan Roberts are philosophers that make her question if anything exists outside our own perception. Professor Lilach Hadany wonders if it’s limited to humans and animals - could other plants hear the falling tree too? And Mat Eric Hart is a sound designer who says that sound is subjective – it’s always tangled up with our own interpretations.Things get truly weird as we delve into the strange implications of quantum physics. If there is such a thing as reality, doesn’t it change when we’re there to observe it? Does the tree even fall if we aren’t there?Presenter: Caroline Steel Producer: Anand Jagatia(Image: Fallen Tree. Credit: Getty Images)

Animals experience all the colds, stomach pains, headaches, parasites, and general illnesses that humans do. But unlike us, animals can’t just grab a painkiller off the shelf at the supermarket to cure it. They don’t have a pharmacy to browse… or at least, not the sort that we’d recognise. Listener Andrew Chen got in touch to ask whether animals use any kind of medicine themselves. After all, our own drugs largely come from the plants and minerals found in wild habitats. So perhaps animals themselves are using medicines they find in nature. Presenter Anand Jagatia speaks with the primate researcher who stumbled across a chimp chewing on a bitter leaf 35 years ago, Professor Mike Huffman, whose observations opened up a whole new field of research. We discover why plants contain the medicinal compounds they do, and how butterflies with brains no bigger than a pin-head are still able to select and use medicine to protect their young. We think of medicine as a human invention - but it turns out that we’ve learnt a lot of what we know from copying the birds, bugs and beasts.Presented by Anand Jagatia Produced by Rory Galloway Image: Chimp eating. Credit: Getty Images

The space industry, with its fuel-burning rockets, requirements for mined metals and inevitable production of space junk, is not currently renowned for its environmental credentials. Can space exploration ever be truly environmentally friendly? Presenter Marnie Chesterton answers a selection of listeners’ questions on the topic of space environmentalism. She starts by examining the carbon footprint of spaceship manufacturing here on Earth, and asking whether reusable rocket ships such as Space X or Virgin Galactic offer a green route for commuting or tourism in low Earth orbit. Just beyond our atmosphere, space junk and space debris are multiplying at an exponential rate, jeopardising our communications and mapping satellites, and even putting our access to the wider solar system at risk. As more probes and landers head to the Moon and Mars, what plans are in place to deal with space debris far beyond Earth? Presented by Marnie Chesterton Produced by Jen Whyntie for the BBC World Service[Image: Space Junk. Credit: Getty Images]

This week CrowdScience investigates the information superhighway connecting mind with body. The Vagus nerve is part of our parasympathetic nervous system, delivering information from all our major organs to the brain stem, and stimulating it can help us switch off our fight or flight response and calm us down. But listener Mags wants to know what science says about its impact on our general wellbeing? Marnie Chesterton learns some deep breathing techniques and discovers how the length of our exhale is closely linked to our heart rate, all of which is important for developing something called vagal tone. Cold water immersion also said to stimulate the Vagus, so Marnie braves a freezing shower, only to discover she needs to get her face wet but keep the rest of her body dry, to avoid what scientists called autonomic conflict, which is when your stress response and calming response are both switched on by the same event. Activating both arms of the nervous system in this way can lead to serious heart problems in some people. New research into the gut-brain axis has shown that the Vagus nerve may be responsible for transporting the so-called happy hormone serotonin, which could have important implications for the treatment of depression. And innovations in electrical stimulation of this nerve means implanted devices may soon be used to treat inflammatory conditions like arthritis. Presented by Marnie Chesterton and produced by Marijke Peters for the BBC World Service Contributors: Dr Lucy Kaufmann, Adjunct Professor of Neurology, NYUMike Tipton, Professor of Human and Applied Physiology, University of Porstmouth Mark Genovese, Emeritus Professor of Medicine, Stanford University Dr Karen-Anne McVey Neufeld, Brain Body Institute, McMaster University[Image credit: Getty Images)

The sudden agony of stubbing a toe or burning a finger can make even the most polite among us swear our heads off. It’s like a reflex, a quick-release valve for the shock. But why do expletives give us such a sense of relief? Why does it sometimes feel so good to swear?We set out to explore the science of swearing, prompted by a question from our listener Gadi. Psychological studies have shown bad language can relieve pain, or even make us stronger; we test out these theories for ourselves, and try to figure out why certain words are charged with such physical power.We don’t just use strong words in shock or anger, either. They can help us to bond with others, to express joy, solidarity, or creativity. And although people curse all over the world, it’s not quite the same everywhere. We hear what people like to swear about in different countries, and whether swearing in a second language can ever be quite so satisfying.Presented by Anand Jagatia Produced by Cathy Edwards for the BBC World Service(Photo: Woman swearing. Credit: Getty Images)

Listener Paula from Kenya is a computer scientist, she can’t help but notice the inequality in her workplace. With only 1 in 10 countries having female heads of state, there is no doubt that men are in charge. Paula wants to know if there is any scientific underpinning to this inequality? Perhaps it can be explained by our brains and bodies? Or does evolution weigh in? Or maybe it is all down to society and the way we raise our boys and girls. The toys and ideals we give our children must surely have an impact. And most importantly, if we want a world run by men and women equally, how can we get there? We hear how Iceland became the most gender equal country in the world. Presented by Marnie Chesterton. Produced by Caroline Steel for the BBC World Service[Image: Men in board room. Credit: Getty Images]

It’s the stuff of fairy tales – a beautiful cottage, with windows, chimney and floorboards … and supported by a living growing tree. CrowdScience listener Jack wants to know why living houses aren’t a common sight when they could contribute to leafier cities with cleaner air. The UK has an impressive collection of treehouses, but they remain in the realm of novelty, for good reasons. Architects are used to materials like concrete and steel changing over time, but a house built around a living tree needs another level of flexibility in its design. That doesn’t mean it’s impossible and CrowdScience hears about a project in the Ethiopian capital Addis Ababa, where architect Ahadu Abaineh made a three-storey, supported by 4 living Eucalyptus trees as a natural foundation.Host Marnie Chesterton meets some of the global treehouse building fraternity, including builder of over 200 structures, Takashi Kobayashi, who adapts his houses to the Japanese weather. In Oregon, USA, Michael Garnier has built an entire village of treehouses for his “Treesort”. He’s developed better ways of building , including the Tree Attachment Bolt, which holds the weight of the house while minimising damage to the tree.Professor Mitchell Joachim from Terreform One explains the wild potential of living architecture, a movement which looks at organic ways of building. He’s currently building a prototype living house, by shaping willow saplings onto a scaffold that will become a home, built of live trees.Photo Credit: Ahadu Abaineh

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’s around a building or a city - is an important everyday capability, one that has been integral to human survival. This week CrowdScience listeners want 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?Marnie also hears that the country you live in might be a good predictor of your navigation skills and how growing up in the countryside may give you an wayfaring advantage. 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 what implications an over-reliance on GPS technology might have for our brain health.Presenter: Marnie Chesterton Producer: Melanie Brown(Photo:Lost man with map. Credit: Getty Images)

Could being happier help us fight infectious disease?As the world embarks on a mass vaccination programme to protect populations from Covid-19, Crowdscience asks whether our mood has any impact on our immune systems. In other words, could being happier help us fight infectious diseases? Marnie Chesterton explores how our mental wellbeing can impact our physical health and hears that stress and anxiety make it harder for our natural defence systems to kick in – a field known as psychoneuroimmunology. Professor Kavita Vedhara from the University of Nottingham explains flu jabs are less successful in patients with chronic stress. So scientists are coming up with non-pharmacological ways to improve vaccine efficiency. We investigate the idea that watching a short feel-good video before receiving the inoculation could lead to increased production of antibodies to a virus. And talk to Professor Richard Davidson who says mindfulness reduces stress and makes vaccines more effective.[Image: Happy couple wearing masks. Credit: Getty Images]

When planning to have a baby, women are expected to give up everything from smoking to alcohol, even soft cheese. But the other half of fertility comes from the sperm, usually provided by a man. So should men also give up their vices to improve the quality of their sperm, and their chances of conception? That’s what Listener Stuart in Australia wants to know. He emailed CrowdScience after he and his wife had been trying to have a second child for two years. He gave up alcohol, and coffee, but wants to know if there is any hard science to back up the idea that this would improve his fertility. To find out, presenter Anand Jagatia speaks with Professor Allan Pacey, a scientist who specialises in the study of male fertility and sperm. He discovers that male subfertility accounts for 50% the problems with getting pregnant. And we’re far from alone. Sperm is a remarkably diverse, but also fragile cell. Across the animal kingdom, different species have problems with male fertility, but have adapted novel ways to improve their chances of reaching the egg. Men often struggle to speak about their fertility, and reporter Chhavi Sachdev tells Anand the impact this has on couples in India who struggle to conceive, or don’t want to. She speaks with fertility specialist Professor Nirmal Kumar Lohiya about how this reticence to speak about fertility is changing. Viruses from Mumps to HIV have long been known to target the delicate sperm production cells in the testicles. Dr Krutika Kuppalli tells Anand why, and what we know about the possible impact of SARS CoV-2 on male fertility.Professor Allan Pacey gives Anand and Stuart some advice for what to do while trying to conceive - don’t wear tight underwear - and get used to talking about your swimmers or even getting them checked out. Contributors: Professor Allan Pacey - Andrologist at the University of Sheffield in the UK. Dr Nicolla Hemmings, expert on bird sperm, Royal Society Dorothy Hodgkin Research Fellow at the University of Sheffield, UK. Professor Nirmal Kumar Lohiya, Fertility specialist and co-developer of RISUG male contraceptive, University of Rajasthan, India Dr Krutika Kuppalli, Assistant Professor at the Medical University of South Carolina, USA Chhavi Sachdev, Reporter and presenter for CrowdSciencePresented by Anand Jagatia, Produced by Rory Galloway(Image: Sperm cells Credit: Getty images)

Covid-19 has prompted a cleaning frenzy. CrowdScience listener William works as a personal trainer in a gym, and while cleaning’s always been part of his job, it’s now taken over much of his working day. He’s constantly wiping down equipment and doing regular deep cleans, and he reckons he can sanitize his hands 40 times in one shift.This kind of routine might strike a chord with many of us, and it’s certainly vital to take hygiene seriously during times of pandemic.But could there be any downsides to all this extra cleaning? There’s a whole world of microbes out there: some, like SARS-CoV-2, make us sick, but others are essential for our health. A rich microbiome is linked to a healthy immune system, while ‘good’ microbes help keep ‘bad’ ones at bay. And what about the chemicals in cleaning products – do they have any unintended consequences for our health?CrowdScience turns to the experts to ask whether our supercharged hygiene routines could damage our immune systems, or promote the spread of superbugs. And we hear why, as long as we have a good diet, plenty of fresh air, and ideally a furry pet, we don’t need to worry too much about being too clean. Presented by Marnie Chesterton Produced by Cathy Edwards for the BBC World Service(Photo credit: Getty Images)

When it comes to speed, humans have got nothing on cheetahs - or greyhounds, kangaroos or zebras for that matter. It’s over long distances we really come into our own: when running for hours or even days, our body structure and excellent sweating skills make us able to outpace much faster mammals.But what are the limits of human endurance? Can we run ever further and faster, and what’s the best diet to fuel such ambitions?This week’s questions come from two CrowdScience listeners in Japan who already know a fair bit about stamina, having run several marathons and long-distance triathlons between them. We head to Greece, legendary birthplace of the marathon, to witness an even more arduous challenge: hundreds of athletes following in the footsteps of the ancient Greek messenger Pheidippides, to run an astonishing 246km across the country. The ever-so-slightly less fit CrowdScience team do our best to keep up, and try to discover the secrets of these runners’ incredible endurance.Presenter: Marnie Chesterton Producer: Cathy Edwards(Photo: a runner in the Spartathlon ultramarathon, with kind permission from the International Spartathlon Association)

One of the more surprising consequences of the pandemic has been the trend for people wanting to move out of cities and back to the countryside. Not everyone has that privilege of course, but undoubtedly for some living in urban areas during lockdown, the lack of access to green spaces took its toll on their mental health and physical well-being. Now, with renewed hope of a global vaccine roll-out, ensuring more people have better access to nature is more important than ever, especially in cities of glass, steel and concrete. Italian CrowdScience listener Enrica loves nothing better than walking along the verdant riverbank near her home after a hard week at work. But is this activity doing more than making her feel good? Is it having an actual effect on her health? Presenter Anand Jagatia meets Enrica and visits a radical scheme in the city of Milan, where officials have been working hard to increase urban green features and have committed to planting 3 million trees and building twenty new parks by 2030.One such idea is the innovative Bosco Verticale - or vertical forest, planted up the side of two high rises apartment blocks. Amongst other benefits It’s hoped it could provide cooling microclimates to reduce the dangers of summer heat, and improve resident’s mental health.Produced by Jennifer Whyntie. First broadcast October 2019.(Photo: Tree lined "tunnel" in the English countryside of West Sussex. Credit: Getty Images)

As regular listeners may recall, CrowdScience has delved into the strange world of fungi before, as we dug down into the forest floor to reveal how plants and trees are connected to the vast mycelial network known as the “wood wide web”. But what makes this network possible and how might it have evolved? Fungi are incredibly clever, or at least , it appears that they’re capable of displaying complex behaviour that gives them the appearance of intelligence. In this episode, we speak to fungal ecologist and author of a new book, Merlin Sheldrake, about fungal “brains”, the evolution of magic mushrooms and zombie insects – the astonishing way certain fungi can take over the bodies of ants and wasps in order to sow their spores above ground.Presented by Anand Jagatia Produced by Rami Tzabar for the BBC World Service.Image: Getty Images

At Christmas, is there a better gift than knowledge? CrowdScience has cooked up its own version of 'secret Santa', with members of the team setting one another the challenge of answering surprising questions from all over the world. Are humans the only animals to exercise? Can you get colder than absolute zero? Why are sounds louder at night? When it comes to food dropped on the floor, is there such thing as the "three second rule"? And, does honey really have healing properties? Producers and presenters from the CrowdScience team speak to all manner of experts, from zoologists through to material scientists, to find the answers. Presenter: Marnie Chesterton Producer: Caroline Steel

CrowdScience listener Simon has a problem. He’s always bumping into things, dropping tools and knocking stuff over. And he’s sick of it. He wants to know what is going on. Was he born like this? Or is it contagious? And most importantly, can he do anything about it, or is he going to be the proverbial ‘bull in a china shop’ for the rest of his life?Host Anand Jagatia gets on the case, investigating the complex coordination needed for the simplest movements, like throwing a ball and catching it. With help from Dr Andrew Green, an exercise physiologist from Johannesburg University, he delves into our secret “sixth sense”, proprioception, which helps us locate our limbs without looking. Anand discovers that an easy task, like kicking a football, needs multiple parts of the brain to coordinate in order to work smoothly. Assistant Professor Jessica Bernard from Texas AMU studies the brain, particularly the cerebellum, a part that controls smooth movements. Dr Bernard explains how tiny glitches and larger lesions in different parts of the brain can make us clumsy in different ways. And how we use our thinking powers to stay balanced; a reason why, as your memory goes with old age, you’re more prone to falling over.Our listener is not alone. Around the world, there is an under- diagnosed condition that affects millions of us. Developmental Coordination Disorder (DCD), also known as dyspraxia is a motor coordination condition that affects 5% of the global population. As Professor Amanda Kirby from the University of South Wales and CEO of Do-It solutions explains, if you can’t tie shoelaces, catch a ball and your handwriting is awful, there’s a chance that you have DCD. There’s a large genetic component, so you are likely to come from a clumsy family.There’s no cure for DCD/Dyspraxia but all of us are capable of becoming better at a chosen task, and there’s a common pathway to mastery, whether that’s bike mechanics or open heart surgery. Professor Roger Kneebone is the author of Becoming Expert, and he talks to Simon about possible solutions to clumsiness, including accepting and living with it. [Image: Man slipping on banana. Credit: Getty Images]