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 to neuroscientists researching how our brains respond to prayer and meditation; and practices mindfulness herself to explore its similarities to prayer. She discovers that having a relationship with God may depend on more than religious practice. And is there a ‘spiritual part’ to our brains? Or is prayer just one activity among many - like going for a walk or playing music - that can have similar effects on our state of mind? Featuring: Professor Andrew Newberg, Director of Research Marcus Institute of Integrative Health, Thomas Jefferson University and Hospital, USA Tessa Watt, mindfulness teacher Ven. Hin Hung Sik, Centre of Buddhist Studies, University of Hong Kong Dr Junling Gao, Centre of Buddhist Studies, University of Hong Kong Dr Blake Victor Kent, Westmont College, USA Presenter: Caroline Steel Producer: Jo Glanville Editor: Cathy Edwards Studio Manager: Tim Heffer Production Co-ordinator: Liz Tuohy(Photo: A crowd of people praying. Credit: Digital Vision/Getty Images)

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 countries leading the way against malaria, with the rollout of the world’s first malaria vaccine programme. Presenter Caroline Steel is joined by a live audience and a panel of experts: Wongani Nygulu, Eggrey Aisha Kambewa and Steve Gowelo. Together they explore questions from our listeners in Malawi and around the world, like why female mosquitoes feed on blood while males drink nectar; why some people are more likely to be bitten by mosquitoes than others; and how we might modify the insects’ DNA to stop them spreading diseases. About half a million children across Malawi have been vaccinated since 2019. We visit a clinic in nearby Chikwawa to meet the staff involved in the vaccination programme there, and the mothers embracing the opportunity to protect their babies against this deadly disease. Recorded at Malawi Liverpool Wellcome Trust (MLW), Blantyre, Malawi. Contributors: Dr. Wongani Nygulu, Epidemiologist, Malaria Alert Centre Eggrey Aisha Kambewa, MLW entomologist, MLW Dr. Steve Gowelo, University of California San Francisco Malaria Elimination Initiative Presenter: Caroline Steel Producer: Jeremy Grange Researcher: Imaan Moin Additional Recording: Margaret Sessa Hawkins & Sophie Ormiston Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy(Photo: A mosquito, that is silhouetted against the moon, bites a human arm. Credit: LWA/Getty Images)

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 in control of our own mathematical fate, or are some people just naturally bad at it? Presenter Anand Jagatia hears about studies of identical and non-identical twins showing how genetics and environment interact to shape our mathematical abilities. Our numerical abilities are not set in stone. It’s always possible to improve, and getting rid of negative feelings and anxiety around maths could be the key, says psychologist Iro Xenidou-Dervou. Some countries seem to support children’s maths skills better than others. China and Finland both rank highly in international league tables; education experts in both countries discuss whether there are any keys to a successful mathematics education. And there is something underlying our ability to do maths in the first place: our number sense. We hear what happens when this number sense does not work as intended – and what can be done about it. Contributors: Professor Yulia Kovas – Goldsmiths University of London, UK Professor Pekka Räsänen – University of Turku, Finland Assistant Professor Zhenzhen Miao – Jiangxi Normal University, China Dr Iro Xenidou-Dervou – Loughborough University, UK Professor Brian Butterworth – University College London, UK Presented by Anand Jagatia Produced by Florian Bohr Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy Studio Manager: Jackie Margerum (Photo: Boy scratching head in front of blackboard. Credit: Jose Luis Pelaez Inc/Getty Images)

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 problem is, while it protects the area immediately behind the rocks, riprap can exacerbate erosion nearby. But there are other, more nature-friendly solutions, including sand dune restoration. Caroline picks up her shovel and helps to re-plant dunes, destroyed in the past by erosion as well as sand extraction for the construction trade. The roots of these plants stabilise the dunes, while building boardwalks prevents further damage from humans. Nature also offers the perfect offshore protection against coastal erosion: coral reefs. These are the first line of defence in absorbing the power of the ocean’s waves. Down on the beach, we see for ourselves just how effective they are. The reefs face threats, but restoration plans are afoot. We visit a nursery that grows corals to plant out on the reefs – and find out about corals’ surprising cannibalistic tendencies in the process. Featuring: Professor Robert Mayer - Director of Vida Marina, Center for Conservation and Ecological Restoration, University of Puerto Rico Nada Nigaglioni - Biology student, University of Puerto Rico Ernesto Diaz - Caribbean Regional Manager at TetraTech Dr Stacey Williams - Executive Director, ISER Caribe Presenter: Caroline Steel Producer: Hannah Fisher Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy Studio Manager: Emma Harth(Photo: Coast restoration measures at Ultimo Trolley Beach, Puerto Rico. Credit: BBC)

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 sand on it. In this first of two programmes, CrowdScience visits Anne’s home in south Florida and finds out how erosion threatens Florida’s famous beaches. Caroline Steel speaks to geoscientist Dr Tiffany Roberts Briggs and hears why it’s such a problem for this tourist-reliant state. Tiffany explains the delicate balance between natural processes and human infrastructure. Meanwhile, the Caribbean island of Puerto Rico declared a state of emergency in April 2023 due to coastal erosion. Caroline witnesses the impacts of erosion first-hand, as Ruperto Chaparro shows her abandoned houses crumbling into the sea. But how can we quantify the rate of erosion? Dr Kevian Perez in the Graduate School of Planning at University of Puerto Rico explains the methods they use to monitor Puerto Rico’s coastlines, and how they are evaluating the effectiveness of different mitigation methods. However, some of the methods used to protect coastal communities from the encroaching sea have done more harm than good. So what are the best ways to tackle this problem? That’s what we’ll be exploring in next week’s programme. Presenter: Caroline Steel Producer: Hannah Fisher Editor: Cathy Edwards Production Co-ordinator: Liz Tuohy Studio Manager: Steve Greenwood and Bob Nettles Featuring: Dr Tiffany Roberts Briggs, Associate Professor at Florida Atlantic University Ruperto Chaparro, Director of Sea Grant Programme, University of Puerto Rico Anabela Fuentes Garcia, Villa Cristiana community leader Dr Kevian Perez, researcher at the Coastal Research and Planning Institute of Puerto Rico at the Graduate School of Planning(Photo: Puerto Rico after Hurricane Maria. Credit: Orlando Sentinel/Getty Images)

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

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 ZooJaak 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 CentresPresenter: 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, UKPresented 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 UniversityPresenter: 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 HarrisFeaturing: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