CrowdScience

How do we know where a sound is coming from?

Another chance to hear this ear-opening episode, exploring a question from CrowdScience listener Chiletso. One day, he heard his son bounce a ball and instantly knew the direction it was travelling. How?

Anand Jagatia sets out to discover what makes left, right, up and down sound so different.

First, he gets blindfolded, so Alan Archer-Boyd, former auditory scientist and lead engineer at BBC R&D, can put his sound localisation skills to the test. It turns out that having two ears and pinnae, those flappy bits of cartilage on the side of your head, help a lot.

Professor Eric Knudsen shares how the barn owl’s asymmetrical ears allow it to hunt mice, even in complete darkness.

And Anand uncovers how far he can push his own spatial hearing. Blind activist and researcher Thomas Tajo teaches him how to echolocate like a bat, and Dr Lore Thaler explains what is going on in the brain of experienced echolocators.

This programme was originally broadcast in March 2023.

Presented by Anand Jagatia Produced by Florian Bohr for the BBC World Service

Image: Boy with hands at his ears Credit: Silke Woweries/Getty Images

For some it's a way to get closer to God, for others a tried and tested way to lose weight - but listener Amine wants to know if fasting has any other, unexpected health benefits? So presenter Marnie Chesterton cuts down on cookies and investigates the science behind low-calorie or time-restricted eating. She hears how some cells regenerate when we're deprived of food, which one researcher says could reduce breast cancer rates. And she finds out what happens in our brains when our bodies rely on our own fat reserves for fuel. Presenter: Marnie Chesterton Producer: Marijke Peters

(Image: Clock on an empty plate. Credit: Getty Images)

Why is it that computers are so much faster than brains at some tasks?

Or could human brains one day be used to better effect? Listener Praveen from India was wondering how it can be that supercomputers are so very powerful compared to the human minds that created them. So CrowdScience, with the help of a small voice-activated guest presenter, is off to discover how the first computers remembered what they were told, how a million processors are being connected together to mimic a small percentage of a human brain, and how the mind-boggling speeds of modern computing is enabling the current leaps in artificial intelligence.

Producer: Alex Mansfield Presenter: Marnie Chesterton

Speakers: Sarah Baines, David Lewis - Museum of Science and Industry, Manchester James Sumner, Steve Furber - University of Manchester Aldo Faisal - Imperial College, London.

(Photo: 3D transparent human head and brain image. Credit: Getty images)

Kenyan listener Docktor can’t help himself. When music is playing he must move to the beat and he wants to know why. What role does dance play in human evolution? And what does dance mean to us? To help answer the many twists and turns in Docktor’s questions, the CrowdScience team heads to one of the most vibrant and diverse dance scenes in the World, Havana in Cuba. For Cubans dancing is at the heart of their cultural identity. They tell stories, bond with others, practice religion and celebrate their African ancestry through dance ¬– which came to Cuba with the slave trade.

For all humans, dancing is intimately connected to our love of music and is likely to be one of our oldest cultural practices. But why would our ancestors have wasted energy on what superficially seems to serve no survival benefits? Evolutionary anthropologist Bronwyn Tarr tells us that one clue lies in the brain. When we dance with others our brains reward us with a cocktail of feel-good hormones and this likely leads to profound social effects.

Presenter Anand Jagatia gets challenged on the dance floor, discovers how deeply rooted dance is in Cuban society and why we should dance more.

Presenter: Anand Jagatia Producer: Louisa Field

(Image: Dancers in Cuba)

Humans have the potential to eat pretty much anything – but the reality is we don’t. Wherever we live in the world, we eat just a small fraction of the foodstuffs available and show strong preferences for certain foods over others. Those preferences can change dramatically from person to person, or as the saying goes – one man’s meat is another man’s poison. Then at the extreme end of the spectrum you get so-called ‘fussy eaters’ who reject so many foods that they are confined to beige diets of crisps, crackers and cereal.

So why do we show such different preferences for food? And why are some people fussier than others? That’s what CrowdScience listeners Orante Andrijauskaite in Germany and Anna Nicolaou in Belgium would like to know, and what Datshiane Navanayagam is off to find out.

She discovers how both biology and culture shape whether a food is disgusting or delicious and learns why we should stop giving children a hard time about finishing their dinner. She also learns how global cuisines evolved and what that can teach us about helping fussy eaters to overcome their food fears.

Presenter: Datshiane Navanayagam Producer: Anna Lacey

(Photo: Fried Bugs in Bangkok night market. Credit: Getty Images)

Carbon dioxide levels are far higher than at any other point in human history, thanks to our reliance on burning fossil fuels. But having pumped huge amounts of CO2 into the air, are there ways to get it back out again? If so, where would we put it all? And the big question: can that help solve our climate change problem, or is it a distraction from the urgent task of reducing our emissions?

When CrowdScience delved into ancient carbon dioxide levels last year, it sparked a flurry of emails from our listeners asking these questions and more, so this week we investigate our options for restoring equilibrium to our atmosphere. Since the CO2 came from deep underground - in the form of coal, oil and gas - can we put it back there? We travel to Iceland where they’re capturing carbon dioxide directly from the air - and turning it into rock. Presenter: Marnie Chesterton Producer: Cathy Edwards

(Photo: Nesjavellir geothermal power plant in Iceland. Credit: Getty Images)

Short-sightedness is reaching epidemic proportions around the world. The way things are progressing, one-third of the world’s population – 2.5 billion people - could need glasses by the end of the decade. And scientists are beginning to understand why: children spend too much time indoors, bent over screens and books. Marnie Chesterton travels to Singapore, where rates of myopia are one of the highest in the world and to see how the government is curbing the condition with an array of tools, from eye-drops to sunshine remedies.

She does so in the hope of better understanding whether screens are bad for children’s eyes, a question raised by a concerned Mexican father, Fernando, about his two-year old daughter.

Presenter: Marnie Chesterton Producer: Graihagh Jackson

(Photo: A little girl wearing headphones while using a digital tablet at home. Credit: Getty Images)

Will gravity on earth ever change? Why do insects fly towards the light? Is the plasma in a TV the same as plasma in a fusion reactor? Why are mosquito bites so itchy? What does the Higgs boson do for the Universe? In a Q+A special, Marnie Chesterton is joined by scientists Malcolm Fairbairn, Kate Lancaster and Erica McAlister to tackle a selection of questions from the CrowdScience inbox.

Presenter: Marnie Chesterton Producer: Alex Mansfield

(Photo: Alates insects light bulb and night. Credit: Getty Images)

Dementia affects nearly 50 million people worldwide – but doctors are still struggling to find a cure. CrowdScience investigates why this particular group of brain diseases are so hard to treat, from the difficulties around diagnosis to why the drugs just don’t currently work.

In the absence of a medical solution is it time to take a new approach? As geneticists develop tests to predict who might develop brain disease, there are others focusing on better care for those who already have it. Presenter Bobbie Lakhera visits a village in the Netherlands helping sufferers live longer independently, and hears how music projects improve non-verbal communication.

Presenter: Bobbie Lakhera Producer: Marijke Peters

(Photo: Neurology research examining the neurons of a human head to heal memory loss or cells due to dementia. Credit: Getty Images)

Since the end of the 19th century, scientists have been predicting we would be eating a meal in a pill, but is it a serious answer to the world’s food problems? That’s what Australian listener Bridget is wondering and whether it’s possible to produce an artificial food source that can provide all the nutrients for healthy human life.

With increasing urbanisation, diets are changing and estimates suggest food production will have to increase some 60 percent by 2050 to keep up with demand. But can we provide all that extra food with limited natural resources and traditional farming methods?

First, Marnie Chesterton finds out what artificial food is currently available and whether the existing products are healthy. And while a meal in a pill might sustain our bodies, will it sustain our minds? The experience of eating involves so much more than simply taking in the right nutrients, as Marnie discovers at the Gastrophysics Chef’s Table, a restaurant and multi-sensory dining experience. On the menu is jellyfish, a possible alternative source of food for the future. It’s in plentiful supply in our oceans, but like eating insects, the thought of it may be disgusting to some, so Marnie explores how sensory-driven strategies can be used to make these food sources more appealing.

CrowdScience also visits the future of farming: A hydroponic vertical farm called Growing Underground, which is built in World War Two air-raid shelters under London. Using LED lighting instead of sunlight, leafy vegetables grow very quickly and need very little space. With higher crop yields per square metre than traditional farming, vertical farms allow fresh produce to be grown in urban centres with less impact on the environment.

Hydroponic farming is something the European Space Agency is also experimenting with as part of Project Melissa, which is developing a closed loop ecological system - using rats instead of astronauts - aimed at one day helping us grow fruit and vegetables on Mars. Listen to the podcast version of the programme to hear this interview.

Producer: Helena Selby

(Photo: Pills on a plate. Credit: Getty Images)

Listener Nikolai sends CrowdScience hunting through space and time with his deceptively simple question. Can we find perfect stillness? You are probably reading this sentence whilst standing or sitting still. So is it a daft question? We discover that there are no simple answers as we unravel the science of motion, which tells us that we cannot always trust our senses to tell us ‘the truth’ about the natural world.

The ancient Greeks believed it was the sun that rises and sets each day and this idea remained until the 16th century astronomer Nicolaus Copernicus showed us that this an illusion – that we are the ones in motion, orbiting the Sun. Later, through the work of Isaac Newton and then Albert Einstein, scientists came to the conclusion that nothing in the universe can ever be truly still. Except perhaps, the fastest thing in the universe – light.

Confused? Don’t worry, so is Marnie Chesterton who sets out to explore not just the science of stillness but also the physics of stopping. To satisfy listener Nikolai’s curiosity about motion in space, CrowdScience also travels to ESA’s European Space Research and Technology Centre in the Netherlands. Here we find out how you stop a space craft and hear the story of when things got prickly for astronaut Tim Peake and his crew when docking at the International Space Station.

Presenter: Marnie Chesterton Producer: Louisa Field

(Photo: Astronaut wearing pressure suit against a space background. Credit: Getty Images)

Are you the master of your own decisions? Independent-minded? A free spirit? Like it or not, the answer is probably no - as we are profoundly influenced by the people around us. But why do humans follow the crowd? CrowdScience listener Cath Danes wants to know and this week we are going to be giving her answers at the BBC’s Free Thinking Festival in Gateshead.

Marnie Chesterton is joined by a crack team of neuroscientists and psychologists, who reveal the secrets behind our inner sheep. We also run an experiment to find out whether you should trust the wisdom of the crowds with life’s big decisions.

Presenter: Marnie Chesterton Producer: Anna Lacey

(Photo: A flock of sheep being herded in a pasture. Credit: Getty Images)

Unlike nuclear fission power stations, which leave harmful radioactive waste to be stored or disposed of for thousands of years, a nuclear fusion power plant would create precious little burden on future generations. The fuel source would be seawater, and the energy created limitless.

Back in the 1950s, the technology to “tame the hydrogen bomb” seemed just a few decades away from practical deployment, and governments across the divide of the cold war shared the challenges, costs and laboratories.

But to the outsider, it might look like progress has been slow. In 1997 the Joint European Torus at Culham in the UK set the world record for energy released from a controlled fusion reaction, but even that was less than the energy was put in.

Keeping the plasma – the super-hot atoms of exotic types of hydrogen – at temperatures many times the temperature of the sun safely in place inside a magnetic field is not a trivial task.

Last year construction of the International Experimental Thermonuclear Reactor, ITER, reached its halfway point at its huge home in France, and if all goes to plan it should produce its first plasma by 2025. The hope is that operational fusion reactions will take place within a decade after that, paving the way for its successor DEMO - which would actually generate electricity - to be built sometime before 2050.

But in parallel with the big intergovernmental roadmap, in recent years a number of small commercial startups have joined the race to achieve commercial fusion energy. With their various different approaches and more ambitious timelines, will the private sector beat the publicly funded science to the goal?

Presenter: Bobbie Lakhera Producer: Alex Mansfield

(Photo of ITER Organization, with permission)

Humans have used dogs' excellent sniffing talents ever since our ancestors figured out that canine companions could help them track down their next meal.

But what about other animals? Can they take us beyond the limits of our own senses? That's what CrowdScience listener Beth wants to know, so we obligingly try to sniff out some answers.

After immersing ourselves in the world of insect senses at our local zoo, we visit an insect lab in Germany to find out whether sniffer bees could take over from sniffer dogs. And could ants help us fly the drones of the future? We meet the scientists trying to turn ant vision into computer code, to send robots into places GPS can't reach.

Presenter: Nastaran Tavakoli-Far Producer: Cathy Edwards

(Photo: A bee on a human finger. Credit: Getty Images)

A cacophony of singing and screaming creatures’ accents are explored to answer: Can animals of the same species from different places communicate with each other? Presenter Geoff Marsh tries to identify how different these calls really sound for CrowdScience.

From wolves to birds to whales and chimpanzees, most animals use sound to communicate, but if groups in different places vocalise in different ways, they may not be able to communicate with others.

CrowdScience questioner, Kitty, sets us on an exploration of the vast and varied world of animal communication with inspiration from her dog Monty.

Presenter: Geoff Marsh Producer: Rory Galloway

(Photo: Three wolves howling on a cold day. Credit: Getty Images)

From worms who time their mating ritual with an inner lunar calendar, to how full moons could cause cows to give birth early. Listener Andreas sends CrowdScience on a mission to separate fact from fiction.

Presenter: Marnie Chesterton Producer: Marijke Peters

Picture: The moon rises over Kadam mountain in Uganda, on January 31, 2018, during the lunar phenomenon referred to as the 'super blue blood moon'. Credit: Yasuyoshi Chiba / AFP / Getty Images

Scientists have been searching for dark matter for 80 years, so CrowdScience wondered whether they could find it faster. Armed with a boiler suit, hard hat and ear defenders, Marnie Chesterton travels over a kilometre underground into a hot and sweaty mine to see how we could catch dark matter in action. She investigates various theories as to what it might be with popping candy and gazes at galaxies to determine how we know it exists in the first place. But most importantly, she questions whether it really matters. And, as our Singaporean listener Koon-Hou askes, what impact would finding it have on our everyday lives?

Presenter: Marnie Chesterton Producer: Graihagh Jackson

(Photo: Finding dark matter could have galactic implications. Credit: Getty Images)

Carbon is special, but is it necessarily the unique building block of life in the universe? Science fiction has long speculated on non-carbon biochemistries existing in the universe – notably in the work of authors such as Isaac Asimov as well as in the popular American TV series Star Trek, which once featured a rock-munching, silicon-based life form called ‘Horta’.

Marnie Chesterton explores the real science behind this intriguing idea and wonders whether in the current search for Earth-like planets elsewhere in the galaxy, we should be looking at completely different possible sets of rules when it comes to the hunt for life?

Producer Alex Mansfield Presenter Marnie Chesterton

(Photo: Saturn viewed from Titan moon. Credit: Getty Images)

How far can you see? A few kilometres down the road? Or do you struggle to see past the end of your own nose? Well one listener thinks he might be able to see 15 quintillion miles away... but can he really? Marnie Chesterton and Bobbie Lakhera are on the case for this week’s multi-question human body special. As well as delving into the power of vision, they also discover why male mammals have nipples despite not needing to breastfeed, and Marnie puts herself in a giant refrigerator in the name of finding out why some people feel the cold more than others.

Presenter: Marnie Chesterton Producer: Anna Lacey

Meet the entrepreneurs turning bugs into food and get top tips on how to cook them. In this week’s episode we return to the topic of edible insects and the story of Kahitouo Hein’s caterpillar factory in Burkina Faso, West Africa. Kahitouo is trying to turn a traditional food like the shea caterpillar, available for just a few weeks a year, into a year-long sustainable staple for the whole population.

We also put your questions about edible insects directly to the researchers in Burkino Faso. Discover the best way to cook a bug, explore the curious effects of hornet venom and find out whether eating insects is better for the environment then eating red meat.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Louisa Field

(Photo: Worker at Kahit’s factory cooking caterpillars)

Most of us instinctively know when someone’s singing and when they’re talking. But since music and speech are both just sounds, how do our brains tell them apart? This week’s question comes from Eugene, a music teacher in Northern Ireland, who often hears music in people’s speech, and wonders why.

Step forward, the ‘speech-to-song illusion’. This curious phenomenon means that when certain spoken phrases are repeated, they turn into music as if by magic. We talk to the Diana Deutsch, the scientist who discovered this illusion, and find out what it reveals about how the brain is adapted to understand both music and speech.

But are some languages more musical than others? Many people around the world speak tone languages, where the pitch of a word affects its meaning. One such language is Dinka, spoken in South Sudan; we meet a Dinka speaker and hear how respecting the melody of the language is essential when writing songs.

Presenter: Datshiane Navanayagam Producer: Cathy Edwards

Dinka recordings courtesy of Elizabeth Achol and Anyang Malual

(Photo:Young woman listening to music on yellow headphones. Credit Getty Images)

Dogs have been living and working with humans for thousands of years. But they’re much more than just pets. As any dog owner will tell you, the bond we have with our canine friends is often so strong that they feel more like family.

So how is it that dogs have come to fit so seamlessly into human life?

That’s what CrowdScience listener Peter Jagger in the UK wants to know, and Marnie Chesterton is off to sniff out some answers. She starts by revisiting a previous episode of CrowdScience based in Sweden, where she saw the dog-human bond come alive during a moose hunt. She then heads to the Dog Cognition Centre in Portsmouth to discover how a unique and often unconscious communication system helps our dogs to understand us. Finally, Marnie finds out about the fate of dogs that are no longer wanted by their humans. After thousands of years of domestication, can they ever live without us?

Presenter: Marnie Chesterton Producer: Anna Lacey

(Photo: Image of young girl with her dog, alaskan malamute. Credit: Getty Images)

Crowdscience revisits the evidence on the best forms of biometric identification. Earlier in the year we explored digital fingerprints, gait (walking style) recognition and iris scanners. Today presenter Anand Jagatia looks at systems which use your face and your voice to identify you. One airline is currently testing facial recognition in airports as a means of replacing your passport. Meanwhile, Anand tries to fool a speech recognition system that measures over a thousand characteristics of your voice in order to protect your identity. But will it be able to cope if you have a cold?

Presented by Anand Jagatia Produced by Marijke Peters.

Picture: Facial Recognition Credit: Getty Images

Reindeer castration, plants get chatty and more quirky science revealed in this Christmas special of CrowdScience where we will also be hearing from the people that make this series possible. That’s you – our listeners.

CrowdScience has been on air for just over a year which means we’ve had over 60 adventures. Every time we put a show together there’s a heart-breaking process where amazing facts we wanted to share end up on the cutting-room floor. To celebrate the holidays we’ve gone scavenging for the best untold stories, edgy science facts and incidents from behind the scene. Presenter: Marnie Chesterton Producer: Louisa Field

Picture: Reindeer in Snow Credit: Getty Images

It lurks behind sofas and collects in corners, apparently appearing from nowhere. But what is household dust? And should we bother sweeping it away? That’s what Australian listener Moshe wants to know and what Marnie Chesterton is off to find out for this week’s CrowdScience. She embarks on a mission to discover not only what dust is made of, but whether it poses any health risks. Although most people sweep it away without a thought, dust contains all sorts of secrets about our habits and everyday lives. Marnie finds out how dust can reveal the pets you keep, the chemicals in your surroundings, the location of your house and how fecal bacteria can uncover whether more men or women live in your home.

Presenter: Marnie Chesterton Producer: Anna Lacey

(Image: Woman Vacuuming Up Dust. Credit: Getty Images)

Trees are old – they transcend human generations – but are they the oldest living things on Earth? This story began in June 2017 when we explored a question sent in from CrowdScience listener William. Many of you got in touch after the programme with questions of your own. So we’re revisiting our trees programme but also exploring another question from listener James, who wants to know what, pound for pound or gram for gram, is the strongest animal alive on Earth today? Marnie Chesterton wrestles with one of them and – spoiler alert – it’s not a gorilla.

Presenter: Marnie Chesterton Producers: Jen Whyntie

(Photo: Kumbuka, a 15-year-old western lowland gorilla. Credit: Oli Scarff/Getty Images)

Dodos are dead, but are they gone forever? Reviving extinct species is a trope of science fiction, but real-life scientists are working on every stage of the problem today. Meeting scientists focused on uncovering ancient animal genomes, or reviving individual cells to conserve species still around, Marnie Chesterton seeks out whether new technologies might, just possibly, bring back the iconic dodo. But what would it take to bring back that most iconic of extinct species? Following listener Rachel’s question, CrowdScience gets to grips with the dodo’s past, and finds out what’s left of this iconic bird, meeting the scientists inadvertently piecing it back together.

Presenter: Marnie Chesterton Producer: Rory Galloway

Picture: An accurate reconstruction of nesting Dodos Photo Credit: Dr Julian Hume

How does technology affect how we fall in love? Crowdscience travels to India to answer listener Erin’s questions about the impact of the internet on our search for soulmates. We meet the traditional matchmaker who says her service provides security in an era of digital fraud. And ask whether computer algorithms are the best way to help people make permanent romantic connections?

Presenter: Chhavi Sachdev Producer: Marijke Peters

(Photo: A couple kiss while taking a selfie. Credit: Getty Images)

Some of us want to be up with the larks, while others are more like night owls. But is our preference down to our genes, or more to do with habits and surroundings? We set out to find the answers, inspired by a question from Kira, a night owl CrowdScience listener in Philadelphia, USA.

Our daily, or circadian, body clocks are a hot topic of discussion at the moment - this year’s Nobel Prize for Medicine went to three scientists who discovered the gene that makes these clocks tick. To answer our listener’s question, we need to know why different clocks tick at different rates, so we visit a specialist sleep centre to see how having a slow-ticking clock makes it hard for you to leap out of bed in the morning.

And the morning sun helps all of us regulate our daily rhythm, so what happens when it doesn’t rise at all? We travel to Tromsø, in the far north of Norway, to see how morning and evening types fare during the long polar nights - and meet the reindeer who seem to be able to switch off their daily clocks altogether. Meanwhile down near the equator, we hear about the hunter-gatherer community in Tanzania where there’s nearly always someone awake.

Sami song, the joik of Ráikku-Ánte, is performed by Ken Even Berg

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Cathy Edwards

(Image: L - Women smiling on a run R - Women DJ. Credit: Getty Images)

Sometimes our memory fails us and we wish facts would just stick better. Listener Mothibi is a student and has spent three years trying to remember as much as possible for his exams. He wants to know how he can train his brain to better to remember things – and does the brain have a limit on how much stuff we can cram into it?

To find the answers presenter Marnie Chesterton seeks help from memory magician, Simon, at the European Memory Championship. Using the loci technique she accomplishes a memory feat she didn’t think possible. Thought to have been developed by the Greeks, the loci method is a technique that enables the brain to remember extraordinary amounts of information. It turns out, we all have the right wiring to remember more and better, but we need to train our brains.

Also, CrowdScience heads to Cambridge University where Marnie Chesterton lands herself in a study. The scientists scan her brain while she exercises her memory muscles and we discover why sometimes memories get muddled up.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Louisa Field

(Image: Woman scratching head, thinking brain melting into lines. Credit: Getty Images)

People often talk about being descended from apes. But go back a bit further and we have a more unlikely ancestor – fish. Improbable as it may sound, the creature that gave rise to every bird, reptile and mammal on Earth today lived a fully aquatic life.

So how did it switch to life on land? And how hard was it to swap swimming for walking and breathing fresh air? That’s what CrowdScience listener Pierre in France wants to know, and what Marnie Chesterton is in Scotland to find out. She goes fossil hunting with members of the TW:eed Project team, as they try to uncover remains of creatures that are crucial in helping solve the puzzle of terrestrial life. She also discovers the landscape these early ancestors walked into – an alien and relatively empty world completely different to what we see today - where grass and flowers were yet to evolve.

But not everything in this story is preserved in rock. Marnie goes to see a living relic of this period of evolution, and finds out what it can tell us about possibly the most important event in the history of our species.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Anna Lacey

(Image: Artists impression of underwater environment of Carboniferous swamp depicting a rhizodont; a large predatory fish. Credit: Mark Witton)

Unpleasant man-made noise is something that disturbs many of us and even damages our health. But as millions more people move into crowded cities around the world, it's a cacophony that we almost unavoidably create ourselves. CrowdScience listener Diana from New York City in the USA got in touch to ask how we can temper the din and live a more peaceful life. Presenter Anand Jagatia heads to an acoustics lab at the University of Salford in Manchester, UK, to meet the researchers and engineers investigating the best ways to make cities more pleasant for our ears whilst still maintaining the ‘buzz’ of city life. And reporter Chhavi Sachdev takes us to Mumbai in India, where we discover how sound mapping is being deployed on the city’s streets as the first step to improve the life and health of its citizens.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Jen Whyntie

(Image: Children cover their ears as the truck convoy front passes. Credit: Getty Images)

Is there any scientific proof of an afterlife? Six months ago, CrowdScience tackled a question from a listener who wanted to know whether there was life after death. But following more listener emails, presenter Marnie Chesterton returns to the subject to investigate the world of ghosts, souls and parapsychology. She meets Professor Susan Blackmore, who studies out-of-body experiences and has spent decades hunting for scientific proof of life after death. And she visits the woman who, despite dying in the 1950s, is alive and thriving on a cellular level and helping scientists find cures for cancer, Parkinson’s and other diseases, in laboratories across the world …

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Produced and Presented by Marnie Chesterton

(Image: Four people sitting around a table having a Seance. Credit: Getty Images)

We test the science behind parasitic therapy to answer listener Michael’s question about whether intestinal worms can help us stay healthy, and visit a deworming programme in a rural Ugandan village.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Marijke Peters

(Picture: Tapeworm in human intestine, Credit: selvanegra/Getty Images)

Carbon dioxide levels in our atmosphere today are higher than at any point in human existence. But going back further into Earth’s history, when do we find concentrations as high as they are now - and what was the planet like back then?

CrowdScience sets out to answer our listener Thomas’s question, travelling back through time with the help of Antarctic ice cores, ancient plant fossils, and microscopic popcorn-shaped organisms called foraminifera, all of which hold clues to past climates.

Enlisting the help of chemists, botanists and palaeontologists, we find out about the huge swings in atmospheric carbon dioxide from prehistoric times to the present day, and ask the all-important question: can this help us understand what's happening to our climate now?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Cathy Edwards

(Image: Polar bear on an ice floe. Credit: Getty Images)

Human Organs are in short supply. But what if you could grow new ones in the lab? And if you donate your body parts to help others, where might they end up? That's what Sarah Gray wanted to know after making the difficult decision to donate the body of her son, Thomas, to medical science after he died from an incurable disease shortly after being born. Sarah then contacted the scientists whose research has been made possible by Thomas’ donation and discovered just how he is contributing to research which, may one day mean that organ donation is no longer necessary.

Presenter Bobbie Lakhera talks to Sarah about her decision and meets some of the scientists working to create biological artificial lab-grown organs, tissues and even bones.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Bobbie Lakhera Producer: Louisa Field

(Image: A doctor taking or delivering a bag containing a human organ for transplant. Credit: Getty Images)

Is it fair to kill invasive species which humans have introduced? When people move around the world, many of their favourite – and not so favourite - animals tag along for the ride. From cane toads through to rats, cats and crayfish, so-called ‘invasive species’ can destroy ecosystems and kill off native wildlife. CrowdScience listener Jude Kirkham wants to know if eradicating these invaders is justified.

One country determined to do something about invasive species is New Zealand, where rats, stoats and possums are causing irreparable damage to the country’s unique bird life. If nothing is done, the iconic Kiwi could be extinct within 50 years. The government and volunteer groups across the country have responded with a plan to eradicate predatory mammals from New Zealand by 2050. But is all the time, energy and money needed to do this really justified? And is it morally right to kill off an animal species that humans introduced in the first place?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Anna Lacey

(Image: Headshot of a Possum Credit: Getty Images)

Just one per cent of vehicles are powered by electricity, but CrowdScience listener Randall from Lac du Bonnet in Canada wants to know how quickly that might change, and whether one day all cars could be electric. Marnie Chesterton begins her journey in an electric car, stuck in traffic on a Los Angeles freeway.

It was in California where the modern electric car revival began in the late 1990s with the EV1 – popular with Hollywood celebrities like Mel Gibson and Danny DeVito. More than two decades on, several countries have pledged to go all-electric in future. The latest is China, who currently lead the world in the number of electric vehicles on the road. But is the planet’s power infrastructure even capable of supporting this global electric dream?

Marnie talks to experts about the practicalities of power supply and charging, takes a ride in an electric prototype with enough acceleration to impress even the most cynical petrol head and discovers an extraordinary vision for the future of personalised urban transport.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Jennifer Whyntie

(Image: Electric power cord plugged in and recharging the electric vehicle Credit: Getty Images)

Nuclear weapons and mega asteroids: what would the aftermath look like? CrowdScience explores past extinction events and future dystopias.

In a past episode, CrowdScience headed to Denmark to find out whether humans could go the way of the dinosaurs – mass extinction triggered by a large asteroid impact 66 million years ago. Although no killer rocks are on route to Earth any time soon, we do not have to look far for other dystopias.

“Do we have enough nuclear weapons to destroy the world?”, listener Ronald from Uganda asks CrowdScience. It turns out there is a web app which can help answer this question. Together with its maker nuclear historian Alex Wellerstein, presenter Anand Jagatia tests hypothetical nuclear disaster scenarios and uncovers the nature of nuclear destruction in interviewees with climate scientist Alan Robock.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Louisa Field

(Image: Explosion of a nuclear bomb Credit: Getty Images)

CrowdScience is uncovering the super-powers of spiders, flies and the most irritating mosquitos.

Anand Jagatia meets spider specialist Jamie Mitchells at London Zoo to find out how spiders create such vast webs and speaks to researchers in Sweden about how they are trying and succeeding in recreating spider’s silk.

Rory Galloway heads to Cambridge University’s Fly Lab to find out how their tiny brains process the world up to four times faster than humans.

And Bobbie Lakhera is at the London School of Hygiene and Tropical Medicine to find out how attractive she is to mosquitos and how they use their super-senses to home-in on our blood.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Laura Hyde

(Image: Close-up of a Jumping Spider. Credit: Getty Images

CrowdScience dives back into a debate about trees and their ability to tackle air pollution. Growing trees take in carbon dioxide and emit oxygen, but their leaves also attract tiny particles, which can get into our lungs and brains. So how good are they at cleaning our clogged up skies? Following on from our original programme, CrowdScience was contacted by a team of researchers in the UK who claim tress may be as much as 50 times better than previously thought at mopping up particles, and learn that hedges may help us stay healthy on roads. Also in the programme, we discover what pollutants are doing to our brains and reveal research which shows that keeping house plants can significantly reduce pollution inside the home.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Marijke Peters

CrowdScience heads to the Sydney Science Festival in Australia where, from a special event at The Powerhouse Museum, we reveal answers to questions listeners have been sending in such as: What living thing has the most toxic venom? What is déjà vu? And why do our fingers wrinkle in the bath? To tackle our listeners’ questions about life, Earth and the universe, presenter Marnie Chesterton is joined by four special guests who will bring the good, weird and bemusing from the world of science to the stage.

Prof Shari Forbes, Professor in Forensic Science at the University of Technology Sydney,aims to help police and forensic teams establish a more precise time of death in missing person and homicide cases.

Dr Katie Mack is an astrophysicist at the University of Melbourne. Her work focuses on finding new ways to learn about the early universe and fundamental physics using astronomical observations.

Dr Jonathan Webb runs the science unit at ABC RN. He is also a former neuroscientist and a former science reporter for BBC News in London.

Dr Alice Williamson is a chemistry lecturer and researcher at The University of Sydney. She hosts a weekly science segment, Up and Atom on FBi Radio in Sydney, co-hosts RN’s Dear Science, and is a regular guest on Dr Karl's Shirtloads of Science podcast.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Marijke Peter and Jen Whyntie

(Image: Koala in tree Credit: Getty Images)

Is it possible to get power from lightning? This was the first CrowdScience question posed by listener John Emochu in Kampala, Uganda, in November 2016. We revisit John’s story as presenter Marnie Chesterton goes hunting for answers at a lightning lab in Cardiff, Wales, where she discovers just what lightning lab is, and how to make a tiny – but very loud – lightning bolt. And we tackle the best of the many questions that came into our inbox about thunderstorms after the original broadcast – from how many types of lightning exist to whether antennae in the clouds could gather electricity. Finally, we head to Kampala to meet listener John to hear just what he thought of the programme and what life is really like in one of the lightning capitals of the world.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Jen Whyntie

(Image: Artist impression of lightning inside a conical flask. Credit: Getty Images)

** Contains some upsetting scenes **

As a species, we humans can be uniquely horrible to our own kind. But are we the only animal to commit murder? Listener Michelle’s question sends CrowdScience trekking – and getting lost - in the Budongo rainforest in Uganda in search of one of Man’s closest relatives, the chimpanzee.

We hear from the scientists, who only days before the team’s arrival at the camp, witnessed a gang of chimps brutally killing another adult. But does chimpanzee lethal aggression pass muster as murder? We head to the capital Kampala for some legal advice and take a look at the grim history of putting animals on trial.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Geoff Marsh Producer: Louisa Field

(Image: Closeup of angry chimpanzee Credit: Getty Images)

How do we end up speaking the way we do? What's happening in our brains and mouths to make us sound so different from each other - even when we’re speaking the same language? This week on CrowdScience we return to our listener Amanda’s question of why there are so many accents, and discover more about what our accents say about us.

We visit Glasgow in Scotland, home to one of the most distinctive dialects of English, to see how social status and age affect the way we speak; and investigate another of our listeners’ questions: is there really such a thing as a ‘political accent’?

But how do babies pick up accents in the first place – and is it impossible to learn new sounds later in life? Presenter Nastaran Tavakoli-Far discovers something unexpected about her own accent, visits a voice coach to try and sound Texan, and uses ultrasound to try and get her tongue round new sounds.

And you can find out how much of an accent expert you are, by taking part in our online quiz.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenter: Nastaran Tavakoli-Far Producer: Cathy Edwards

(Image: Woman holds hand near ear and listens carefully alphabet letters flying in. Credit: Getty Images)

People said they’d never catch on. Mobile phones, the internet and even robot assembly lines all once seemed like niche technologies. But today they are at the heart of the modern world.

But just how far can technology go? Could machines start to compete with humans in making complex and life-changing decisions, like those made by lawyers and judges? That’s what CrowdScience listener Zackery Snaidman from Orlando in the US wants to know and presenter Marnie Chesterton has set out to find answers.

She starts at a hackathon in London, where she witnesses the birth and design of the UK’s new online court. And in Uganda, she hears how technology and social media is filling a crucial gap left by a shortage of human lawyers. Marnie is also surprised to discover a simple algorithm that regularly out-performs human judges in making bail decisions.

But could technology bring as many problems as it solves? Could seemingly ‘unbiased’ computers hide the prejudices of their makers? And more fundamentally: With our future liberty at stake, is the world ready to leave their fate in the hands of machines?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Anna Lacey

(Image: Digitized Lady Justice. Credit: Getty Images)

A billion people across the world smoke cigarettes, and many would agree it’s the hardest habit to quit. One such smoker, listener Sharif, emailed CrowdScience from Uzbekistan to ask if we could find out why giving up is so difficult. Marnie Chesterton travels to San Francisco to meet addiction experts and discovers how nicotine tricks smokers into thinking tobacco’s good for them. And we meet ex-smokers at a weekly therapy session aimed at retraining the brain.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Marijke Peters

(Image: Lit cigarette. Credit: Getty Images)

Earlier this year Crowdscience explored the question of time. Back then we were on a mission to uncover what the real time is and how we're able to measure time to ever greater degrees of accuracy. But as ever, the programme uncovered more questions than answers so presenter Anand Jagatia is back to try and find out where time comes from, why it runs forwards and not backwards, what happens to time in a black hole and does time even exist beyond our experience of it? We speak to Claudia Hammond, author of a book that reveals the mysteries of time perception and the man who defined time for the online Encyclopaedia Britannica, tells us if time really exists or not.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Rami Tzabar

(Image: Abstract clock image. Credit: Getty Images)

We're always up for a challenge on CrowdScience but this week’s question, which comes from an artist, tests our limits as we investigate the nature of thought itself – something that has puzzled scientists and philosophers since ancient times. Undeterred, presenter Nastaran Tavakoli-Far heads off to the Spanish island of Ibiza to visit listener Romanie in her painting studio and attempt to peer into the workings of her mind. As we explore the relationship between thought and language, why not join in with our experiments to discover if you’re thinking visually or verbally? We find out how language can affect thinking in surprising ways – why German speakers might see a bridge differently from Spanish speakers, how being bilingual can make you a better driver and even why some languages give their speakers a remarkable sense of direction.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenter: Nastaran Tavakoli-Far Producer: Cathy Edwards

(Image: The Thinker a bronze sculpture by Auguste Rodin. Credit: Getty Images)

David in Bogota might have raised a few eyebrows in the CrowdScience office with his questions – can plants talk? And can they hear us talking to them? But actually scientists now know that plants do have the ability to communicate with the world around them to a much greater extent than previously thought. Some scientists even talk about plants being able to “hear” a hungry caterpillar or the sound of running water, while others argue that we should not anthropomorphise plants.

One underground communication network, affectionately dubbed the Wood Wide Web by scientists, is made of fungi that grow off the roots of plants. The network lets plants forge alliances, friendships and business partners.

But as we learn nothing is free in nature. In return for their haulage services, the fungi which make up the network siphons off some of the sugar produced during photosynthesis by the plants. Presenter Anand Jagatia goes foraging for answers in the woods together with fungal ecologists.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Louisa Field

(Image: Misty path running through woodland. Credit: Getty Images)

Back when Charles Darwin presented his theory of evolution by natural selection, French biologist Jean-Baptiste Lamarck suggested something different - that the changes you are exposed to during your lifetime can be passed on to future generations. By this theory, giraffes have long necks because, over generations, they have stretched them, reaching for leaves.

This theory became laughable when genes were discovered as the means of heredity. Lifestyle choices cannot be passed down in your DNA, or so we thought….But recently this idea has returned and a new field of biology has emerged called epigenetics – which looks at how the genes we inherit from our parents are controlled and modified by their life experience and the choices they made.

Marnie Chesterton meets the survivors of the Dutch Famine of World War Two, whose grandchildren show health effects from that event despite being born three generations after the starvation of 1944.

As the new field of epigenetics develops, does this mean Lamarck was right all along? Can your lifestyle be passed on to future generations and does this mean we need to rethink our traditional view of evolution?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presented and Produced by Marnie Chesterton

(Image: Grandmother, Mother and Daughter in a kitchen. Credit: Getty Images)

Listener Ros Allen wondered why it always seems to rain on her village but not the one a mile away. It’s all down to microclimates. CrowdScience explores the impact of microclimates on our lives, discovers how more rain can help an English tea plantation and reveals the deadly effect of the urban heat island. Marnie Chesterton also talks to a local project in New York City, the Cool Roofs Program, that aims to reduce the urban heat effect, helping to mitigate the impacts of climate change. But just how much of a difference can measures like this really make?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Marijke Peters

(Image: Women standing on the edge of a forest with an umbrella. Credit: Getty Images)

Trees transcend human generations – but are they the oldest living things on Earth? CrowdScience listener William from London, UK, got in touch to ask what the oldest tree or other organism on our planet is. Presenter Marnie Chesterton heads out to meet one of our older arboreal cousins to see how we can work out its age - without cutting it down to count the rings. But whilst certain individual trees can live for thousands of years, some that live in colonies can survive for much longer – perhaps up to 80,000 years old. Along the way, Marnie asks what other organisms contend for this title, what the word ‘oldest’ really means, and even ponders whether some creatures could actually be immortal.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Jen Whyntie

(Image: Ancient Bristlecone Pine Forest. Credit: Getty Images)

You don’t have to be a “super-recogniser” to know that human facial features are extremely varied. Just look around you. Yet look at a most other animals and you’d find it hard to tell individuals apart. So why are human faces so diverse?

We’ll also be finding out why salt tastes salty (warning: lots of spitting and gargling ahead) and one listener wants to know what would happen if one of the key ocean current systems, the North Atlantic Conveyer, slowed down or stopped altogether. Presenter Marnie Chesterton heads to the beaches on the West Coast of Scotland in search of answer. Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk Presenters: Marnie Chesterton and Geoff Marsh Producers: Laura Hyde and Jennifer Whyntie

Childbirth is different for everyone. Depending on who you ask, it’s one of life’s greatest and worst experiences - and can be anything from traumatic and excruciating to life-affirming and spiritual. But what pretty much every mother will agree on is that it hurts. But why is such a fundamental aspect of life so painful? And why do some women find it worse than others?

Presenter Gareth Barlow – who doesn’t expect to be giving birth ever – goes on a quest to understand the experience of female labour pain and why evolution hasn’t given women an easier ride. He discovers the latest research into the nature and experience of pain and whether the idea of male/female pain thresholds, is a real thing. We also hear from CrowdScience listeners about their own experiences, and find out if having a supportive birth partner can help bringing new life into the world that little bit easier.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Gareth Barlow Producer: Anna Lacey

(Image: New born baby with mother. Credit: Getty Images)

Even if you spent your entire life on a plane, the chances are you’d never crash – commercial air travel is remarkably safe. But after hearing about a recent air tragedy, two brothers in Kampala wondered if commercial airplanes could ever have ejector seats – like fighter jets do - to give passengers a last option for escape.

We meet 98-year-old John Oliver “Jo” Lancaster, one of the first people ever to eject out of a plane, and discover the seemingly insurmountable barriers to fitting ejector seats into passenger jets. And we find out that an awful lot of work goes into making flying as safe as it is, as we visit an air accident investigation lab, practise an emergency exit from a passenger cabin and deal with a multiple engine failure …in a plane simulator.

But are any safety ideas as radical as ejector seats on the horizon? We assess a controversial design that would parachute the entire passenger cabin down to earth should the worst happen.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Cathy Edwards

(Image: Person blasting out of a plane cockpit on an ejection seat Credit: Martin-Baker Aircraft Company Ltd)

Sex is responsible for the large variety of life on earth. Without the two sexes there is no sexual reproduction which means no shuffling of the genetic make-up – and no survival in a changing environment. But why do we have two sexes in the first place and does nature determine your sex? It’s with these questions and more that listener Du from Singapore persuaded the CrowdScience team to investigate the weird and wonderful world of sex. You might think that Nature would have standardised something as important as ensuring the continuation of the species. Far from it – species do sex in many different ways – some stranger than others.

Presenter Marnie Chesterton unpicks the zoological oddities of sex and along the way learns about her own sex chromosomes. We also meet an unlikely bird keeper, who is the proud owner of a female duck that is morphing into a male. Will her boyfriend, a male mandarin duck, mind the change?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Louisa Field

(Image: Male and female mandarin ducks. Credit: Getty Images)

Biometrics are being used everywhere to recognise us. On this edition of CrowdScience we try out the tech that tells us apart. We find out just how unique our irises are and meet a man who can pick people out from a crowd of thousands just by analysing the way they walk.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Marijke Peters

(Image: Fingerprints being looked at under a magnifying glass. Credit: Getty Images)

Our planet is getting rather cosy. In just over 200 years, the global population has grown from 1 billion to almost 7.5 billion – and the best estimates suggest it’s going to keep on increasing. But just how far can it go? When will we reach ‘peak human’? That’s what CrowdScience listeners Alan Donaldson and Francoise Brindle want to know: what’s the latest estimate for how many people the Earth can support?

It’s a question that’s been bothering some of the world’s greatest thinkers for hundreds of years, and now presenter Marnie Chesterton goes on her own quest for answers. Her journey takes her through the technology and innovation that keeps our growing population alive, and she looks to Dhaka, Bangladesh, to find out what a more densely populated world might feel like. But are there signs that things are already levelling off? And could improving photosynthesis allow populations to grow without destroying the environment?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Anna Lacey

(Image: People on busy street. Credit: Getty Images)

Mining asteroids, moons or even other planets has remained firmly within the realm of science fiction. But as certain elements become increasingly scarce on Earth, private companies and even nation states are looking to make extra-terrestrial mining a reality. Presenter Marnie Chesterton heads to an Earth-based mine in Scotland to see just how tricky space mining could be, and what possibilities it holds. On the way she discovers what laws govern this new far frontier, and hears from a space prospector who already has designs on key sites for exploration. Could our solar system's asteroids really become self-fuelling gas stations for spaceships?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Jen Whyntie

(Image: Double the Rubble Artist Concept. Credit: NASA)

For most people the idea of chewing on a caterpillar or tucking into a tarantula is pretty unpalatable. Yet according to the United Nations, some two billion people around the world consume insects regularly. This prompted World Service listener Saman from Pakistan to ask the BBC CrowdScience team “are insects a serious food source?”

To tackle this question, we head to Burkina Faso in West Africa where shea caterpillars are an important part of the local diet in a place where food security is low and malnutrition is high.

Here we follow scientist Charlotte Payne as she tries to crack the tricky science behind the caterpillar’s life cycle and see how local entrepreneur Kahitouo Hien is trying to change lives and reduce malnutrition with edible caterpillars.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Anand Jagatia Producer: Louisa Field

(Image: Bowl of cooked Caterpillars. Credit: BBC/Anand Jagatia)

Why do we have so many accents - even when we’re speaking the same language? What's happening in our brains and mouths to make us sound so different from each other? This week’s question from listener Amanda takes CrowdScience to Glasgow in Scotland: home to one of the most studied - and distinctive - accents of English.

Along the way we visit a voice coach to try and learn a Texan accent, use ultrasound to see what different sounds look like inside our mouths and find out how a brand new dialect was formed when many accents collided in New Zealand.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Nastaran Tavakoli-Far Producer: Cathy Edwards

New Zealand Mobile Unit recordings courtesy of Ngā Taonga Sound & Vision

(Image: A mouth screaming white letters. Credit: Thinkstock)

Do your joints ache when it's raining? Are you blighted with headaches when the wind picks up? If the answer’s yes then you're definitely not alone. People have been linking their heath to the weather since the time of the Ancient Greeks - but is the effect real?

CrowdScience heads for the hills and gets closer to the clouds to have a go at answering this 2,500 year old question.

People who believe they’re sensitive to the weather aren’t always taken seriously. But presenter Datshiane Navanayagam hears about the latest ground-breaking experiments that show there's a lot more to it than folklore. And if you've ever wondered why you're particularly prone to aches and pains in the winter, the answer could all be in your genes.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Datshiane Navanayagam Producer: Anna Lacey

(Image: Man looking up to grey clouds. Credit: Thinkstock)

Can we really live on Mars? Or exist in a virtual world? And why does movie science sometimes have us shouting at the screen? Our panel of scientists and sci-fi experts reveal all in this special edition of CrowdScience recorded live at the South by Southwest Conference & Festivals in Austin, Texas, USA. To tackle all of our listeners’ questions about science in film, presenter Marnie Chesterton is joined by a team of specialists.

Prof Polina Anikeeva is an MIT materials scientist and engineer whose research focuses on developing devices that work directly with the human nervous system. A sci-fi fan, Prof Anikeeva knows just how realistic brain-computer interface movies such as Avatar and The Matrix are.

Former NASA astronaut Dr Mae Jemison is a medical doctor, engineer, educator and entrepreneur, and the first African-American woman to go into space aboard the shuttle Endeavour in 1992. She is leading the 100 Year Starship Project, which aims to take humans beyond our solar system by 2112.

Prof Clifford Johnson is a theoretical physicist at USC whose work leads him to think about space-time, black holes, and extra dimensions, making him a regular contributor to documentaries about science and sci-fi films.

Rick Loverd is Program Director of The Science & Entertainment Exchange at the National Academy of Sciences, which inspires better science in Hollywood by introducing entertainment professionals to scientists and engineers. The Exchange has consulted on movies including Star Trek: Into Darkness, Iron Man 2 and Thor.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Jen Whyntie

Audio clip from Gravity Warner Bros. Pictures Director: Alfonso Cuarón

Audio clip from Interstellar Warner Bros. Pictures and Paramount Pictures Director: Christopher Nolan

(Image: Matt Damon in The Martian. Credit: Getty Images) (Image: Zoe Saldana in Avatar. Credit: Getty Images) (Image: Matthew McConaughey in Gravity. Getty Images)

The human race is getting fatter. But is it our fault? There are a whole host of factors influencing our weight - how many of them can we control?

CrowdScience discovers how factors like our environment and our genes can tip the scales in the wrong direction.

We visit an apartment complex originally designed for Olympic athletes, to see if people can get fitter just by living there. And from a brand new menu plan for overweight Mumbai police, to hormone injections that stop you getting hungry, CrowdScience asks the experts what we can do if we’ve been dealt a bad hand when it comes to our weight.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Cathy Edwards

(Image: Women and a Man standing next to each other holding hands. Credit: ThinkStock.)

Trees take in carbon dioxide but they also convert some of the toxic gases in our air. How much help can trees give us in fighting air pollution and could where we plant them make an even bigger difference? Crowdscience reports from the side of some busy roads on how canopy coverage may be part of the answer. At a lab in Louisiana one scientist is putting oak leaves through their paces to find out how effective they are at cleaning our air.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Marijke Peters

(Image: Trees in a forest Credit: Julian Stratenschulte/Getty Images)

Our listener Joseph’s question might sound more sci-fi than science show. But as Marnie Chesterton discovers, robots have already entered the realm of medicine and are likely to become more important in the future. A visit to the operating theatre at the University College Hospital in London together with surgeon Caroline Moore reveals that robots take the scalpels out of surgery by letting surgeons treat patients with prostate cancer without having to make a single cut. And chatting to Molly the robot alongside Dr. Praminda Caleb-Sully at Bristol Robotics Laboratory, Marnie discovers that robots could be the helping hand we need to look after a growing elderly population.

Machines win when it comes to data-processing. But what about empathy and intuition? Such characteristics would require machines to reach a level of artificial intelligence (AI) which critics say is decades away. The sceptics insist humans will always play a key role in healthcare. But others suggest that not only will AI change everything – but technology will one day eliminate the need for us to go to the doctor ever again.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

(Image: Three Robots on Display at the Science Museum in London. Credit: Carl Court/Getty Images)

Presenter: Marnie Chesterton Producer: Louisa Field

A few weeks ago, CrowdScience asked if it pays to be nice. We found that the answer is yes – if you’re a human. But if being social is so great, why aren’t all animals doing it?

That’s what our US listener Tony wants to know. After listening to ‘Does it Pay to be Nice?’ he rightly pointed out that cats lead mostly solitary lives - but don’t seem any worse off for it. So why have they taken this path? And are they any less advanced than a social species as a result?

Presenter and naturalist Tim Cockerill heads to the rainforests of Madagascar in search of answers. After lots of trekking through the undergrowth, he finds out why so many animals choose group living and what’s different about cats to make them go it alone.

But does it matter which way of life an animal takes? Tim discovers that for humans at least, being social has given us much more than we imagine.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Tim Cockerill Producer: Anna Lacey

(Photo: Cat lying on floor. Credit: Getty Images)

Death is one of life’s few certainties – or is it? To answer listener Pratibha’s question from New Delhi, India, presenter Marnie Chesterton asks medical and scientific experts if there is any evidence that humans could somehow come back into existence after their demise. We start at the end, by asking just what death is – and it turns out to be perhaps surprisingly complicated, especially if cold temperatures are involved. As another listener, Camilla, from Washington DC, USA points out, there are some animals that can become totally frozen over winter and return to life in spring. How does this happen, and could it have implications for the idea of deep-freezing humans – known as cryogenic preservation? Alternatively, if entire bodies might prove difficult to save, could we download our brains’ contents for later reboot instead? It sounds like science fiction, but a global network of scientists are pursuing the goal of cybernetic immortality: uploading our minds to an artificial brain in a robot avatar. Marnie heads to a brain-computer interface lab where she gets wired up to control a computer game by thinking, and discovers just how difficult it is to export thought, and how much we still have to learn about our brains. Could the way to cheat death ever be digital?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Jen Whyntie

Earth’s surface may be 70 percent water but many places are struggling to access it. We look at a range of water supply options including delivering it by tanker. In Malta we meet a man trying to solve its water problems, with a clever contraption to recycle sewage.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Produders: Cathy Edwards and Marijke Peters

(Image: Tanker ship. Credit: Getty)

It sounds like a simple question – what is the time? But look closer and you realise time is a slippery concept that scientists still do not fully understand. Even though we now have atomic clocks that can keep time to one second in 15 billion years, this astonishing level of accuracy may not be enough. The complexity of computer-controlled systems, such as high-frequency financial trading or self-driving cars which rely on the pinpoint accuracy of GPS, could in future require clocks that are even more accurate to ensure everything runs ‘on time’.

But what does that even mean? As Anand Jagatia discovers, time is a very strange thing. He visits the origins of modern time-keeping at the Royal Observatory in Greenwich and meets scientists at the National Physical Laboratory who have been counting and labelling every second since the 1950s. He meets Demetrios Matsakis, the man who defined time and visits the real-life ‘Time Lords’, at the International Bureau of Weights and Measures (BIPM) in Paris to find out how they co-ordinate the world’s time and why the leap second is ‘dangerous’.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

From Chihuahuas to Great Danes, Mexican Hairless to Afghan Hounds, dogs are the most diverse mammal on the planet. There are currently over 500 recognised breeds worldwide with almost every conceivable combination of size, shape, coat, colour and behaviour.

But why are there so many different kinds of dog?

That's what listener Simon St-Onge in Quebec, Canada wants to know – and CrowdScience has taken up the challenge.

Presenter Marnie Chesterton heads to Sweden, a world-class centre of canine research, to sniff around for answers. She finds out how the grey wolf morphed into the vast variety of dogs we have today, and heads out on a moose hunt with one of Scandinavia's most ancient breeds.

But are dogs really as different as they seem on the surface? The dog genome is revealing more about man's best friend than ever before – and could now be the answer to understanding both dog and human health.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

(Image: Tika, the Russian-European Laika)

Modern Martian hunting involves looking for the tiniest evidence of life. But when presenter Marnie Chesterton found out that a scientist she was meant to be chatting to about cleanliness had previously worked for NASA, the topic of space bugs turned out to be too intriguing to ignore, especially when a CrowdScience listener asked us a question on a similar theme. Could Earth's microbes hitch a ride on our missions to Mars and colonise the Martian soil? As the European Space Agency's ExoMars venture gears up to launch a rover in 2020 that aims to find out whether there is, or has ever been, life on Mars, we head to the programme's clean rooms and Mars Yard - a giant planet-simulating sandpit - to find out. Marnie meets space engineers whose job is to prevent microbial contamination of Mars whilst creating robots that can find signs of life on the Red Planet. And she discovers that planetary protection is not all about remote aliens: Could tiny Martians have already arrived here on Earth via a meteoric hitch hike?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Jen Whyntie

(Picture: Mars from the Hubble Space Telescope. Credit: NASA)

To be healthy you need to be clean – or so we’ve thought throughout human history.

The dazzling array of antibacterial products that exploded onto the scene in the 20th century took things to the next level, with their promises of eliminating 99.9% of germs.

But could an obsession with cleanliness actually be bad for us? There’s a whole world of microbes out there: some make us sick, but others are essential for our health.

How do we tell the difference? Listener Younes’s question gives CrowdScience the chance to sift the good dirt from the bad, with the help of hygiene expert Professor Sally Bloomfield. Along the way we soap up our hands with schoolchildren in Mumbai, get knee deep in mud on an English farm, and find out why snuggling up to a cow might be a good idea.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Presenter: Marnie Chesterton Producer: Cathy Edwards and Marijke Peters

Is there a killer asteroid with Earth’s name on it? The dinosaurs ruled for many millions of years before coming to their violent end. Will humanity prevail or are we doomed to succumb like the dinosaurs? It’s a question that will keep you up at night. No wonder our listeners Zarin and Pablo wanted to know more.

To find out, Anand Jaggtia heads to Denmark to see first-hand the evidence for a giant asteroid impact, written into the rocks at Stevns Klint. And we will hear from scientists at Nasa who are keeping a careful eye out for asteroids on collision course with Earth. Also, we discover that asteroids have a lot to answer for, maybe even our own existence.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Why can't we use energy from the waves of the sea to create all the electricity that we need? Listener Michael in Kingston, Jamaica wants to know. Living on a Caribbean island means he’s never far from the might of the ocean – so could it power his house?

Presenter Greg Foot heads to one of the world’s leading wave energy test locations, the coast of Cornwall in the UK, to find out. There, he witnesses the challenges of the marine environment, from metre high waves in a giant indoor test tank to being buffeted on a beach where a 25km cable runs beneath his feet to a grid-connected offshore test site. And find out if Greg’s plan to feel the power of the waves first-hand on a research boat works out – in the middle of winter, in the northern hemisphere.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

Picture: Waves, Credit: Oli Scarff/Getty Images

Most of us want to be nice. But is it all it's cracked up to be? It's a question that's been nagging at listener Tony in Illinois, USA, for over 25 years. While studying at university, the lecturer asked him whether competing or co-operating was the best strategy for success – essentially, does it pay to work together or should we sharpen our elbows and look after number one?

Nastaran Tavakoli-Far goes in search of answers. She talks to a local hero about why he puts his life on the line for others, and visits a neuroscientist to find out what happens in the brain when we help others. Her quest also leads her to question whether women really are the more co-operative sex and how an animal called a kudu might reveal how human co-operation evolved in the first place.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

(Image: John Cook from Hertfordshire Fire and Rescue Service. Credit: Anna Lacey / BBC)

How would a fourth dimensional being appear to humans?

"It would look just weird" is one way to answer the question 'How would a fourth dimensional being appear to humans?' But it's more complicated than that - theoretical cosmologist Andrew Pontzen describes how objects are viewed from one dimension to another, and how it might affect parking spaces.

Also on the programme: our panel of experts discuss bubble experiments, a theory that the Black Death was a virus, space elevators, algae as a biomass fuel, what affects the speed of digestion in our gut, a short definition of dark energy and the question is it true our DNA has alien properties?

With Helen Czerski, department of mechanical engineering, University College London; virologist Jonathan Ball, University of Nottingham; and cosmologist Andrew Pontzen, University College London.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk.

(Image: Stripes and points of light, one guess what a 4th dimension might look like, Credit: Thinkstock)

What effect does air travel have on the climate? That is the question listener Neil sent CrowdScience from New Zealand. If you have ever looked up at the sky and seen the wispy white streaks that airplanes leave behind, then you are looking at one of the major environmental impacts of air transport – contrails.

To find out more, Anand Jagatia goes on a journey through the rugged, lava-ridden Icelandic landscape with earth scientist Thor and discovers how both natural events like volcanic eruptions as well as man-made acts of terror can shed light on the environmental impact of aircraft. Plus, we meet a man who tailgates 737 airliners to measure their emissions.

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk.

Where did the first viruses come from? They have the potential to wipe out life on Earth. But could life on Earth itself have evolved from the first viruses? Like the chicken and the egg, there are fierce arguments about which came first and rival scientists get quite cross about it all.

We take a dip into the primordial soup of creation and try to answer listener Ian's excellent question. Along the way, we revisit medieval plagues, travel to Texas to the largest urban bat colony in the world and take a walk through the dense mosquito-infested Ugandan forest that gave its name to the Zika virus.

Plus, we reveal how a virus is responsible for the placenta. No virus, no placenta; no placenta, no humans?

Do you have a question we can turn into a programme? Email us at crowdscience@bbc.co.uk

This programme has been edited since broadcast to remove a brief reference to ‘bubonic plague’ being included in a list of viral diseases.

(Photo: HIV viruses attacking a Cell. Credit: ThinkStock)

How much electric energy storage would it take to run the average home for 24 hours? Also: When will it be economical to locally store several days of electric energy for our home? Listener Gus in Texas, USA, wants to know – especially because he’s one of many people around the world who sometimes face lengthy power cuts.

Presenter Marnie Chesterton takes Gus’s question to energy experts. She heads to two national research facilities: The National Grid Scale Energy Storage Lab at University College London, and the Joint Center for Energy Storage Research at Argonne National Laboratory near Chicago – which originated from the early stages of the Manhattan Project. On the way, Marnie finds out where the word ‘battery’ came from, discovers why our mobile phone batteries gradually die with age, and hears how the next generation of power storage could change the world.

Presenter: Marnie Chesterton Producer: Jen Whyntie

(Picture: Isolated cabin at night Credit: Ed Jones/AFP/GettyImages)

What do scientists think is outside our universe? Asks Rebecca Standridge from San Francisco in the US.

It’s a question which goes right to the limits of human understanding.

We look for the answer using balloons, bubbles and the world’s oldest radio telescope.

If you have a question about science that you'd like us to investigate email crowdscience@bbc.co.uk.

Photo: Lovell telescope Jodrell Bank

Is it possible to get power from lightning? This was the first CrowdScience question posed by listener John Emochu in Kampala, Uganda.

Presenter Marnie Chesterton goes hunting for the answer at a lightning lab in Cardiff, Wales. What is a lightning lab? And how was she able to make a tiny – but very loud – lightning bolt? Marnie also discovers humanity's early history with lightning, how aeroplanes are protected from lightning strikes, and where the greatest number of thunderstorms occur in the world.

With contributions from John Emochu, Rhys Phillips, Chris Stone, Rachel Albrecht, Shaaron Jimenez and Manu Haddad.

Picture: Photograph of lightning from the US Environmental Protection Agency. Credit: Eric Vance, EPA

Today there are over eight billion people on Earth. That’s an awe-inspiring figure… but how does it compare to the vast numbers who came before us? Listener Alpha wants to know how many people have ever existed, so CrowdScience sets out to do a historical headcount.

The Population Reference Bureau in the USA estimated this number back in the 90s, and have been updating their calculations ever since. Demographer Toshiko Kaneda explains how their model works, the assumptions it makes – and the huge uncertainties around the number it comes out with.

We first need a date for when ‘humans’ first began, so Caroline travels to the Natural History Museum in London to meet human evolution expert Chris Stringer, and marvel at his collection of replica fossil skulls. Chris demonstrates how to distinguish our species, Homo sapiens, from other species like Neanderthals. When did these species first appear - and which of them count as human?

And once you know where to start the clock, how do you estimate the numbers of people alive at different points in history? For a population demographer like Walter Scheidel, it helps that some ancient civilisations kept detailed censuses, a few of which have survived to the present day. Caroline and Walter pour over one of these census fragments, and learn how to combine them with other archaeological clues to get some very rough numbers.

And finally: what does the future of our population look like? Poonam Muttreja from the Population Foundation of India discusses developments in the world’s most populous country, as well as the big demographic trends ahead for humanity.

Presenter: Caroline Steel Producer: Phil Sansom Additional Recording: Umaru Fofana Editor: Cathy Edwards Production Co-ordinator: Connor Morgans Studio Manager: Sue Maillot

Featuring: Toshiko Kaneda, Technical Director of Demographic Research, Population Reference Bureau Chris Stringer, Research Leader in Human Evolution, Natural History Museum London Walter Scheidel, Professor of Classics and History, Stanford University Poonam Muttreja, Executive Director, Population Foundation of India

We spend a lot of our time thinking about climate change, but listener Paul has a question that isn’t usually part of the conversation. He wants to know whether a hotter atmosphere will affect how often volcanoes erupt, or make them more explosive when they do.

CrowdScience travels to New Zealand to search for answers, exploring volcanic craters and discovering traditional Maori knowledge about volcanoes.

Contributors: Geoff Kilgour, Volcanologist, Geological and Nuclear Sciences Taupo, New Zealand Heather Handley, Volcanologist, University of Twente, The Netherlands Pouroto Ngaropo, Historian and Matauranga Māori expert, Rotorua, New Zealand

Presenter: Caroline Steel Producer: Emily Bird Editor: Cathy Edwards Production Co-Ordinator: Connor Morgans Sound Engineer: Steve Greenwood

(Photo: Icelandic volcano. Credit: KRISTINN MAGNUSSON/Getty Images)

Many of us have habits that calm us down in times of stress. Things we find deeply comforting, like sucking our thumb or biting our nails. We might not even be aware we’re doing them, but they play a fundamental role in helping us regulate our emotions.

Our question this week comes from CrowdScience listener and nail-biter, Ash. He wants to know where these habits come from. And since his pet dog is also a nail-biter: do we share these traits with other animals?

Recently, a video of a mouse cleaning up a man’s shed took the internet by storm. Was this a house-proud mouse, or was it the animal's way of making sense of a frenetic environment? An emerging field of scientists focusing on animal behaviour and emotions help us shed some light on such questions.

Along the way we meet a dog training specialist, learn what a sniffari is, go for playtime with a thumb-sucking otter, and visit an OCD clinic. We’ll also be getting tips on how to give your pets the best home environment, and meet an animal enrichment officer in South Africa, who knows how to spot the signs of an unhelpful habit developing.

Contributors: Karolina Westlund, Ethologist, Stockholm University and ILLIS Ben Terry, CBT Therapist, Priory Hospital North London Karin Pienaar, Animal Behaviourist, COAPE International Candice Ward, Animal Behaviourist, Johannesburg Zoo

Jaak Panksepp clip: The science of emotions: Jaak Panksepp at TEDxRainier

Producer: Robbie Wojciechowski Presenter: Alex Lathbridge Editor: Cathy Edwards Production co-ordinator: Connor Morgans Additional recording by Elna Schutz

(Photo: Portrait of border collie puppy biting a curtain. Credit: Rawlstock/Getty Images)

Crowd Science listener Maik wants to know what the BMI is and what his BMI score says about his body. He trains dogs for a living and wonders if, like different breeds of dog, we simply have different body types? Marnie Chesterton comes up with some answers, talking to doctors about how the BMI is used and misused in clinical practice, and looks at some alternative methods for measuring our body composition. She also sits down with philosopher Kate Manne to discuss the realities of living in a fat-phobic world. We hear from Tonga in the South Pacific, where high BMI scores have labelled the country highly obese. But this is not necessarily how Tongans see themselves. And Marnie finds out if the BMI will continue to be used across the world as an important health marker or whether it is destined for the scrap heap of medical history. Contributors: Professor Kate Manne Dr Francesco Rubino Dr Naveed Sattar Professor Brendon Noble Technician Leah Siegel Fononga Pulu Sela Latailakepa Presenter: Marnie Chesterton Producer: Richard Walker Editor: Cathy Edwards Production co-ordinator: Connor Morgans Studio manager: Emma Harth

CrowdScience listener Gregory wants to know what affects the way we see the colours of the world. He was looking at a blue summer sky with a friend and they got to wondering whether they both see the same colour blue. So what does influence our vision of the colours that surround us? Could eye colour have anything to do with it? And can we ever really know if your blue sky is the same as mine?

Caroline Steel comes up with some answers, talking to colour scientists about their research into the multiple factors that enable us to see in multi colours, from the intricate biology of our eye to the changing environment around us.

She also investigates her own colour vision and solves a personal mystery, discovering why the world has always looked a slightly different colour from each eye.

Contributors: Professor Jay Neitz, Department of Opthalmology, University of Washington, US Professor Hannah Smithson, Department of Experimental Psychology, University of Oxford Dr Juan Perea García, researcher, Department of Cognitive Psychology, University of Leiden Dr Lauren Welbourne, researcher, Department of Psychology, University of York Dr Adam Bibbey, lecturer in sport, Department of Sport, Oxford Brookes University

Presenter: Caroline Steel Producer: Jo Glanville Editor: Cathy Edwards Production co-ordinator: Connor Morgans Studio manager: Jackie Margerum

(Photo: LWA)

Storing your data in ‘the cloud’ might sound like an ethereal, intangible place, but it’s actually a physical location - a data centre. CrowdScience listener Art is worried about how much energy and water data centres are consuming. He’s from Ireland, where data centres are gobbling up almost 20% of the national electricity supply and that’s growing, fast.

So how much energy and water are data centres using globally? And how can they become more sustainable? To answer Art’s question CrowdScience heads to chilly western Norway to visit a data centre hidden deep within a mountain, that’s said to be one of the most efficient in the world. And we hear how a data centre in South Africa is saving water and dealing with crippling power cuts by generating its own renewable energy.

Do we just need to stream less TV and reduce our email inbox? With the help of carbon footprint expert Mike Berners-Lee, we crunch the numbers to find out.

Featuring: Svein Atle Hagaseth, CEO of Green Mountain data centres in Norway Mike Berners-Lee, Professor at Lancaster University’s Environment Centre and consultant at Small World Consulting Thulani Ncube, Group Energy Lead at Africa Data Centres

Presenter: Anand Jagatia Producer: Sophie Eastaugh Editor: Cathy Edwards Studio Manager: Donald MacDonald Production: Jonathan Harris & Connor Morgans Additional Recording by: Kobus van Niekerk

Why do humans have wisdom teeth if so many of them get removed soon after they appear?

Wisdom teeth, the third molars in the back of our mouths, are so called because they normally appear in late teenage, early adulthood – the time in life we supposedly have learned some wisdom. But around 25% of people don’t develop all four. Of those that do emerge, it is not uncommon for them to appear at nasty angles, jutting into the tooth next door causing potentially dangerous infections and pain. Because of this, for decades many people have them surgically removed.

Listener Khaleel was preparing to have his remaining wisdom teeth removed when he wrote to CrowdScience to ask about them. Given that they can seem to cause more harm than good, why has evolution resulted in these troublesome teeth? But many people have perfectly uneventful relationships with their wisdom teeth, so have we perhaps removed more than we needed to over the years?

Anand Jagatia chews it over with the help of surgeons and dentists to try to extract the truth – why DO we have wisdom teeth?

Featuring: Tanya M Smith, Professor in the Australian Research Centre for Human Evolution at Griffith University, Australia Patrick Magennis, Consultant Oral & Maxillofacial Surgeon at University Hospitals Aintree, Liverpool UK Verena Toedtling, Dentist and Specialist Oral Surgeon, UK

Presented by Anand Jagatia Produced by Alex Mansfield

When the first person set the very first clock, how did they know what time to set it to? This question, from listener Chris in the UK, sends CrowdScience off on a quest into the history of timekeeping.

From sundials to water clocks, from uneven hours to precision seconds determined by the vibration of an atom, we examine how we came to measure time. We visit possibly the oldest working mechanical clock in the world to discover how its time was originally set; and hear how the time we go by today is not quite the same as it was in the past.

Will all this be enough to solve Chris' question, or has he stumped the team?

Featuring:

Ian Westworth, Clock Mechanic Dr. Chad Orzel, Associate Professor of Physics and Astronomy at Union College Anna Rolls, Curator of Clocks, Clockmakers’ Museum Peter, Guide, Salisbury Cathedral Dr. Jun Ye, Physicist at NIST (National Institutes of Standards and Technology) and The University of Colorado, Boulder.

Presenter: Caroline Steel Producer: Margaret Sessa-Hawkins Editor: Cathy Edwards Production Co-ordinator: Jonathan Harris Studio Manager: Jackie Margerum

(Photo:Stopwatch on red background. Credit: Martin Poole / Getty Images).

In 2011, CrowdScience listener Amanda survived the devastating earthquake in Christchurch, New Zealand.

It arrived unannounced - as all earthquakes do - leaving her with no time to prepare a response. So Amanda wants to know whether science will ever be able to give us advance warning of quakes.

To explore her question CrowdScience heads to New Zealand to meet listener Amanda, as well as the brains behind the country’s earthquake forecasting models. We dig in a field for thousand-year-old tectonic clues that could help us understand when the next earthquake might strike. But even if we could get a head start against a quake, would we respond in the right way?

Please note: earthquake response advice varies by location. Please check local guidance and individual building procedures.

Featuring:

Nicola Litchfield, Principal Scientist in Paleoseismology at GNS, Wellington, New Zealand Matt Gerstenberger, Seismologist and leader of the National Seismic Hazard Model, GNS, Wellington, New Zealand Andy Howell, University of Canterbury, New Zealand Lauren Vinnell, Lecturer in Emergency Management at the Joint Centre for Disaster Research at Massey University

Presenter: Caroline Steel Producer: Emily Bird Editor: Cathy Edwards Production: Jonathan Harris, Jana Holesworth Sound Engineer: Steve Greenwood

(Photo: Earthquake damage in Christchurch. Credit: John Crux Photography)

Have you ever been through a romantic break up, unable to shift the ex from your thoughts? You are, obviously, not alone…

Listener Elkin, experienced just that. But rather than wallowing in self-pity, he sought out an explanation. Where better to get it, than from CrowdScience. Now, Alex Lathbridge is putting on his thinking cap to find out why we daydream?

Presenter: Alex Lathbridge Producer: Harrison Lewis Editor: Martin Smith Production: Jonathan Harris

Featuring:

Giulia Poerio, Lecturer in Psychology, University of Sussex. Kalina Christoff, Professor of Psychology, University of British Columbia. Eli Sommer, Israeli Professor of Clinical Psychology, University of Haifa. Sophie Forster, Reader in Psychology, University of Sussex

(Photo: Man daydreaming surrounded by clouds. Credit: jacquesdurocher / Getty Images)

Presenter Marnie Chesterton and the team pit their wits against a multitude of mind-bending puzzles from an old TV gameshow - all in the name of answering a question from Antonia in Cyprus: how do we work out how clever someone is? Is IQ the best measure of cleverness? Why do we put such weight on academic performance? And where does emotional intelligence fit into it all?

In the search for answers Marnie and the team are locked in rooms to battle mental, physical, mystery and skill-based challenges, all against the clock.

Unpicking their efforts in the studio are a global team of cleverness researchers: Dr Stuart Ritchie from Kings College London, Prof Sophie von Stumm from York University and Dr Alex Burgoyne from Georgia Institute of Technology in the US.

They are challenged to face the toughest questions in their field: Why do men and women tend to perform differently in these tests? Is our smartness in our genes? And what about the Flynn Effect – where IQs appear to have risen, decade after decade, around the world.

Producer/presenter: Marnie Chesterton Editor: Richard Collings Production co-ordinator: Jonathan Harris

(Photo Man doing puzzle. Credit: Getty Images)

What evidence is there for a semi-aquatic period in human evolutionary history? That’s the question that’s been bothering listener Dave in Thailand. He thinks our lack of hair and love of water might indicate that, at some point, we were more water-based than we are now. But what does science have to say on the matter?

The theory that our ape ancestors returned to the water for a phase in our evolutionary history is a controversial idea that most scientists disagree with.

Anand Jagatia chats to Dr Melissa Ilardo, assistant professor at the University of Utah, about our dive reflex - a physiological response we display when submerged underwater, which helps direct oxygen towards vital organs. But this is not a response that is unique to humans - it is found in all mammals. Experts say it developed long before all apes split off in the evolutionary tree.

To find out more about the theory itself Anand hears from John Langdon, emeritus professor at the University of Indianapolis. He explains why the aquatic ape theory is not generally accepted by anthropologists, what the fossil record can tell us about our evolutionary path and why evolution is much more complex than the aquatic ape hypothesis suggests.

While there may be little evidence of a semi-aquatic period in our evolutionary past, there are some communities around the world that have adapted to utilising their watery environments in more recent evolutionary history.

Anand speaks to Dr Nicole Smith-Guzman at the Smithsonian Tropical Research Institute who has found evidence that ancient populations in Panama were habitually diving in the sea for shells and seafood. She explains how she can piece together evidence from different sources to detect the activity of ancient populations. And Dr Melissa Ilardo explains how evolutionary pressure can cause physical changes in isolated communities, as our bodies ultimately adapt to help us thrive in more watery environments.

Producer: Hannah Fisher Presenter: Anand Jagatia Editor: Richard Collings Production co-ordinator: Jonathan Harris Sound engineer: Jackie Margerum

(Photo: Woman swimming underwater. Credit: Petrelos/Getty Images)

Our question this week comes from a father and his two young boys. They want to know whether it’s possible to plant enough trees to soak up all the extra carbon we are putting into the atmosphere? The quest to find answers takes us to a remote reforestation project in the Carpathian Mountains in Romania which could be a model for other projects looking to tackle the climate crisis through reforestation. We speak to experts to find out how much tree planting and reforestation can do in helping combat the climate crisis. Presenter: Caroline Steel Producer: Margaret Sessa-Hawkins Editor: Richard Collings

Noise pollution from vehicles in the public space has a huge impact on human health. But as the world switches to quieter electric-powered means of transport there’s a debate about whether we will actually see any noticeable improvement to our quality of life.

Discovering more than just engineering solutions to the problem, CrowdScience visits one of the world’s loudest cities, Mumbai in India. It is a place where noise has become a way of life. But is that all about to change?

Presenter: Alex Lathbridge Producer: Richard Walker Editor: Richard Collings

Welcome to Part 2 of our year-end extravaganza and the final episode of 2023!

We’ve had a brilliant year hunting down the answers to your science questions - on everything from food and phobias to friction and flying - and in this episode presenter Anand Jagatia is revisiting some of the best stories we covered. We’re bringing you some extra juicy bonus content that we couldn’t fit in to those shows first time round.

Hannah Fisher joins Anand to revisit an episode she produced about the microbiome, the community of tiny organisms living both on and inside us. During that show Hannah took presenter Caroline Steel to a microbiome museum in the Netherlands called Micropia. And one thing from Micropia that never got aired was the kiss-o-meter, a device that measures how many microbes you exchange when you kiss! Micropia curator Jasper Buikx explains the science behind the kiss-o-meter, and then Caroline Steel tries it for herself!

Microbes aren’t just living on and in humans and animals - they’re pretty much everywhere in our environment. And to illustrate this CrowdScience producer Marijke Peters brings Anand a bonus interview with a professional surfer who’s also a bioscientist.

Cliff Kapono undertook a scientific project travelling around the world to take microbiome samples from surfers in different countries. He discovered a fascinating global connection. Surfers are linked together by microbes on their skin that they get from the water around them. Intriguingly, he describes how this might affect our perception of who we are as humans.

Caroline Steel updates us on an interview she did with indigenous Australian astronomer Peter Swanton. Peter appeared on CrowdScience telling an ancient Australian folktale about a man who sacrificed himself to save his brother. The story, which has been handed down through several generations, provides possible evidence for an early observation of a supernova. You can hear that story in the episode “Why is the sun at the centre?”

Today we hear two extra stories that originally got cut from the broadcast due to time constraints. They are beautiful and poignant tales that reveal the depth of indigenous scientific achievement and the extraordinary significance of the night sky.

Presenter: Anand Jagatia Producer: Phil Sansom Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Managers: Tim Heffer and Cath McGee

Featuring:

Jasper Buikx, scientific curator & spokesperson, ARTIS-Micropia Prof. Cliff Kapono, surfer & molecular bioscientist, School of Ocean Futures at Arizona State University Peter Swanton, indigenous research associate, Australian National University

Welcome to Part 1 of CrowdScience’s year-end extravaganza! It’s an extra-festive episode this week. For those who celebrate it, Christmas is the perfect time to pause and look back at the year just gone. Here on CrowdScience we’ve had a great 2023: we answered dozens of listener questions, ranging from climbing plants and ostriches to panic attacks and the weight of the internet.

This week presenter Anand Jagatia magically appears with a Santa’s sack full of special features. We’re catching up with some of our favourite guests from the past year and answering some of the extra questions that we never got the chance to cover.

First up we hear from presenter Tim Clare who we first heard in the episode “Why do some people have panic attacks?” He takes Anand through his new book – it's about board games: why we play them, how they’ve existed throughout history and what he’s learned about himself in the process of writing it.

Then it’s time for a bonus question. The CrowdScience team often get questions about noise pollution. One listener got in touch to ask whether the transition to electric vehicles will reduce this noise. Acoustic scientist Kurt Fristrup and epidemiologist Erica Walker give their perspectives on this question, and how sound and noise can sometimes be very different things. CrowdScience listener Marie - who originally starred in an episode about why she doesn’t have any sense of time - returns. Since the programme she has been speaking to psychologists about her problem and tells Anand what more she’s learnt.

We received another bonus question after a show in 2023 about AI: why can’t artificial intelligence be designed to explain it’s decisions? Producer Phil returns to data scientist Briana Brownell from the original episode to ask her why AI decision making is so very complex.

Finally, as it’s the season for holiday music, we’re asking what makes the genre so distinctive? Composer Jane Watkins - who originally created the sound of a panic attack for a CrowdScience episode - brings in her musical keyboard to demonstrate what makes a Christmas song so specifically ‘a Christmas song’.

It’s all topped-off with the premiere of a happy and heart-warming song performed by the CrowdScience Christmas Choir – a little gift for our loyal listeners.

Presenter: Anand Jagatia Producer: Phil Sansom Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Managers: Tim Heffer and Cath McGhee

Featuring:

Tim Clare, author/poet/podcaster Dr. Kurt Fristrup, acoustic scientist, Colorado State University Prof. Erica Walker, RGSS Assistant Professor of Epidemiology, Brown University School of Public Health Marie Bergholtz Briana Brownell, data scientist Jane Watkins, composer