Listener Julie lives close to the coast in New Zealand and wants to know why the water that washes up on the beach isn't fresh. How exactly does all that salt get into the world's oceans? In India, a country where salt became symbolic of much more than well-seasoned food, host Chhavi Sachdev visits coastal salt farms and a research institute dedicated to studying all things saline, to better understand our relationship with salty seas. The team also ventures to a very briny lake on the...

CrowdScience listener Eleanor was lying in bed one rainy evening, listening to the radio. She lives in New Zealand, but happened to hear a weather forecast that told her it was raining in the UK too. She started wondering: could it be the same rain falling there and outside her window in New Zealand? Can a raindrop really travel all the way around the world? There are a number of routes the droplet could take, including traveling as moisture in the air. Presenter Caroline Steel meets...

It’s often said that fine wine gets better with time, and this week’s oenophile listener Jeremy has a cellar full of dust-covered bottles. He is curious whether chemistry can account for the range of flavours that develop as wine matures, but also wonders why some of it tastes like vinegar if you leave it too long? We head off to the Bordeaux region of France, where vines were planted almost 2,000 years ago. Here, winemakers are joining forces with scientists to better understand wine...

The Blue Ridge Parkway is 469 miles of beautiful vistas, a mountainous road that winds from Virginia to North Carolina in the USA. The route is peppered with elevation signs, telling you how many metres above sea level you are. Which has CrowdScience listener Beth wondering: as we are told that sea level is rising, will all the elevation signs need repainting? It’s a task she’s passed over to the CrowdScience team, who like a difficult challenge. The height of an enormous pile of rock like...

Prayer and meditation are key features of religious and spiritual practices around the world, suggesting they’re intimately linked to the human condition. But what is going on in the brain during prayer? And is praying beneficial for our mental health? CrowdScience listener Hilary is keen to find answers to such questions. She’s a counsellor with a strong Christian faith, and is curious to know whether science can illuminate religious and spiritual practices. Presenter Caroline Steel talks...

Mosquitoes are responsible for more human deaths than any other animal. These tiny creatures transmit many diseases, but the most devastating is malaria. It kills over half a million people every year, most of them children. So why are people still dying of malaria in such large numbers, when so much time and money has been invested in trying to eradicate it? What do we know about mosquitoes and malaria, and what do we still need to learn? CrowdScience visits Malawi, one of the African...

When CrowdScience listener Israel from Papua New Guinea received a bad grade on a maths test in third grade, he looked around the class and realised that almost all the other students had received a better result. Since then, he has always wondered: why are some people better at maths than others? And Israel isn’t the only one to think about this: our listeners from all over the world describe their relationships with numbers, which run the full gamut from love to hate. So are we all...

Coastlines around the world are changing, causing serious problems for the many communities living near the sea, as well as vital and fragile coastal ecosystems. In the second of a two-part special on coastal erosion, CrowdScience explores the best ways to tackle this problem. Presenter Caroline Steel visits the Caribbean island of Puerto Rico to see the various methods they use to protect their coasts. First up: ‘riprap’ – rocks strategically placed to keep the encroaching sea at bay. The...

Around the world, coastlines are constantly changing due to the power of waves, currents and tides. Coastal areas are also some of the most heavily populated and developed land areas in the world. So it’s not hard to see how the natural process of coastal erosion can cause serious problems for us. It’s an issue that’s been bothering CrowdScience listener Anne in Miami Beach, Florida. She can see the beach from her window and wonders why after every storm, several trucks arrive to dump more...

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...

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...

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...

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...

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...

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...

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...

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....

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...

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...

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...

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...

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...

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...

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:...

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...