CrowdScience

We’re all familiar with the sensation of sleepiness – heavy eye-lid, that warm, fuzzy feeling. But, one CrowdScience listener wants to know, what’s actually going on in our body and brain when tiredness takes over? Presenter Marnie Chesterton takes up the challenge and follows a trail that leads to circadian scientists working at the NASA Ames research centre in Silicon Valley. It turns out aviators and astronauts take sleepiness very seriously indeed. Marnie sends out roving reporter Anand Jagatia to investigate how our psycho-motor skills are affected by fatigue in a driving simulator. And we ask how does sleepiness change with age? Why, when tired, do adults crave a nap but children become ever more excitable? And what the hell’s going on with teenagers? We have some answers. (Photo: Tired woman taking a nap at work sitting at office desk. Credit: Getty Images)

Most of us take the ability to speak fluently for granted, but for listener Breeda it has been a lifelong struggle. She has asked CrowdScience to investigate whether there is a cure for stuttering and, if not, what the best way to live with it is. Breeda is not alone, as stammering is a neurological condition that affects 70 million people worldwide. The CrowdScience team head to Oslo in Norway to follow a group of young people who have signed up for a highly disciplined and potentially life-changing training course. The first milestone is to learn to say their name without a stutter. For many, this is a huge challenge that triggers years of distress and anxiety. With hundreds of muscles and many parts of the brain being involved, speaking is one of the most complex tasks that humans perform. Scientists have discovered subtle differences in the insulation surrounding nerve cells, so-called myelin, between people who stutter and those who don’t. This irregularity may be the source of a tiny time delay in signals between crucial regions of the brain that need to work closely together to produce speech. In the future, it may be possible to stimulate certain brain areas to boost growth and connectivity. Presenter: Gareth Barlow Produced by Louisa Field for the BBC World Service (Image: Illustration of humans speaking with quotation marks, credit: Getty Images)

Crowdscience listeners Michael and Ricky have been walking a tributary of the River Thames in London, UK. They’ve noticed that there are loads of fish, which have only returned in recent years thanks to clean water initiatives. But what about salmon, they wonder? Could they one day return too? If they popped some salmon eggs in the river, would they return to spawn later on in their lives? Marnie Chesterton heads to Norway to find out whether it’s possible. There, she follows the life cycle of salmon, from birth to death and travels to the salmon’s spawning grounds, before following their path out to sea and beyond. She explores the science behind ‘natal homing’ - returning to the place of your birth in order to reproduce. It isn’t just confined to salmon. But how does it work? Marnie also learns to fish as she joins an active research project that's evaluating if escaped farmed salmon are threatening their wild counterparts by interbreeding. Could this stop salmon swimming home? Back in the UK, Marnie finds out if all this Norwegian expertise could be transplanted to a river in London? Quite possibly, but it's not without its challenges, as the UK's Environmental Agency found out after attempting to re-introduce salmon into the River Thames. Presenter: Marnie Chesterton Produced by Graihagh Jackson for the BBC World Service (Photo: The mighty Wild Atlantic salmon travelling to spawning grounds in the Scottish highlands. Credit: Getty Images)

Faced with one cake and eight hungry people, it’s pretty obvious how maths underpins reality. But as mathematics gets further from common sense and into seemingly abstract territory, nature still seems to obey its rules - whether in the orbit of a planet, the number of petals on a flower, or the structure of an atom. But what exactly is the relationship between mathematics and reality? That’s the impossibly difficult question CrowdScience has been set this week by our listener Sergio in Peru. It’s one that’s been pondered by humans for millennia: the Greek philosopher Pythagoras believed “All is number”. Is maths a human construct to help us make sense of reality - a tool, a model, a language? Does maths create its own reality? Or is it reality itself? CrowdScience explores these questions with the help of experts from the fields of philosophy, mathematics and science: Dr Eleanor Knox, Dr Eugenia Cheng, Professor Lucie Green, Alex Bellos and Stefano Centineo. Presenter: Marnie Chesterton Produced by Cathy Edwards for the BBC World Service (Photo: A young woman with her eyes closed standing in front of chalkboard, working out maths formulas. Credit: Getty Images)

Human life expectancy has been increasing for decades. In many developed countries, we can now expect to live into our 80s, and it isn’t uncommon to live to 90 or even 100 years old. But eventually our bodies fail, old age is undoubtedly a clear indicator of approaching death. This fact annoyed 79 year old CrowdScience listener Bill, who emailed in to set presenter Geoff Marsh the task of seeking out the secrets to a longer, healthier life. Bill has a personal target to live to 200 years old, so can he do it? Well some people appear to age more slowly. In one part of Costa Rica, people commonly hit their hundredth birthday. CrowdScience’s Rafael Rojas visits these Central American centenarians to ask them their secrets to a longer life. Then, in interviews with the best age researchers around the world, including Professor Linda Partridge and Professor Janet Lord, Geoff reveals the science behind longer lifespans, and what people can do to live for longer, healthily. Presented by Geoff Marsh Produced by Rory Galloway (Image: A group of older men sitting together at an event, Costa Rica. Credit: Rafael Rojas)