Maintaining friendships is one of the most cognitively demanding things we do, according to Professor of Evolutionary Psychology Robin Dunbar. So why do we bother?  Robin has spent his life trying to answer this deceptively simple question. For most of his twenties, he lived with a herd of five hundred gelada monkeys in the Ethiopian highlands. He studied their social behaviour and concluded that an ability to get on with each other was just as important as finding food, for the survival of the species. Animals that live in large groups are less likely to get eaten by predators. When funding for animal studies dried up in the 1980s, he turned his attention to humans.   and discovered there’s an upper limit to the number of real friends we can have, both in the real world and on social media.   
Producer: Anna Buckley

Robin Dunbar on why we have friends

Professor Jim Al-Khalili talks to leading scientists about their life and work, finding out what inspires and motivates them and asking what their discoveries might do for us in the future

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With 86 billion nerve cells joined together in a network of 100 trillion connections, the human brain is the most complex system in the known universe.  Dr. Hannah Critchlow is an internationally acclaimed neuroscientist who has spent her career demystifying and explaining the brain to audiences around the world. Through her writing, broadcasting and lectures to audiences – whether in schools, festivals or online – she has become one of the public faces of neuroscience. She tells Professor Jim Al-Khalili that her desire to understand the  brain began when she spent a year after school as a nursing assistant in a psychiatric hospital. The experience of working with young patients - many the same age as her - made her ask what it is within each individual brain which determines people’s very different life trajectories.  In her books she’s explored the idea that much of our character and behaviour is hard-wired into us before we’re even born. And most recently she’s considered collective intelligence, asking how we can bring all our individual brains together and harness their power in one ‘super brain’. And we get to hear Jim’s own mind at work as Hannah attaches electrodes to his head and turns his brain waves into sound. Producer: Jeremy Grange

Hannah Critchlow on the connected brain

The reputation of the nuclear industry has had highs and lows during the career of Dr Fiona Rayment, the President of the Nuclear Institute. But nowadays the role of nuclear science and engineering has become more widely accepted in the quest for carbon net zero. Growing up in Hamilton, Scotland during a time of energy insecurity, Fiona was determined to understand more about why her school lacked the energy to heat up all of the classrooms or why there were power cuts causing her to have to do her homework by candlelight - and in nuclear she knew there was a possible solution.  But it’s not just in clean energy that Fiona has spent her career, she’s also been involved in investigating how nuclear science can be used in treating cancer and space travel, as well as promoting gender diversity in the nuclear industry.  Speaking to Professor Jim Al-Khalili, Fiona discusses how she’s always tried to keep close to the science during her career in order to keep her ‘spark’! Produced by Jonathan Blackwell

Fiona Rayment on the applications of nuclear for net zero and beyond

We are fascinated by dinosaurs. From blockbuster hits to bestselling video games, skeleton exhibitions to cuddly plushies, the creatures that once roamed the planet have fully captured our imagination, giving us a portal to a completely alternative Earth. And it’s likely new species are still out there, waiting to be found...   Dr Nick Longrich is a palaeontologist and senior lecturer at the University of Bath, and he studies the dinosaur bones that many have overlooked. By rummaging through the back rooms of museums, he finds traces of never-before-described dinosaurs and goes on the hunt for other specimens to confirm or deny his hunch. Through these adventures, he’s discovered over a dozen new species, painting a more detailed picture of our prehistoric world.  Nick is also fascinated by rare ‘one in a million year’ events – like asteroid collisions or mega volcanic eruptions – and investigates how the event that wiped out the dinosaurs created the world we live in today. From an Island off the coast of Alaska, Jim Al-Khalili discovers how Nicks early immersion in nature has trained his brain to spot the subtle differences in the world around us that many would overlook.  Produced by Julia Ravey.

Nick Longrich on discovering new dinosaurs from overlooked bones

Dr Sheila Willis is a forensic scientist who was Director General of Forensic Science Ireland for many years.  She has spent her life using science to help solve cases, working on crime scenes and then analysing material in the lab, and presenting scientific evidence in court. It’s a complicated business. Forensic science relies on powerful technology, such as DNA analysis, but it cannot be that alone - it’s also about human judgement, logical reasoning and asking the right questions.  It is these fundamentals of forensic science that Sheila has fought for through her long career and what she fears may be becoming lost from the field now. We find out what happens when the two very different worlds of science and the law clash in the courtroom. How to walk the line of presenting scientific evidence where there is pressure to be definitive where often science cannot be - and what this part of the job has in common with food packaging. And what makes a good forensic scientist?  We’ll turn the studio at London’s Broadcasting House into a live crime scene to see if host Professor Jim Al-Khalili would be any good as a forensic investigator… Produced by Gerry Holt

Sheila Willis on using science to help solve crime

Professor Charles Godfray, Director of the the Oxford Martin School tells Jim Al-Kahlili about the intricate world of population dynamics, and how a healthy obsession with parasitic wasps might help us solve some of humanity's biggest problems, from the fight against Malaria to sustainably feeding a global community of 9 billion people.

Robin Dunbar on why we have friends

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