As recently as a few years ago, the idea of a self-administered injection that would deliver proven weight-loss results might have sounded fantastical. Today, these medications are a reality and a global phenomenon; hailed in many quarters as “miracle drugs" for their success in treating obesity and diabetes. They do this by replicating a gut hormone called GLP‑1, which tells the brain you’ve eaten enough and nudges the pancreas to release insulin; and this hormone was discovered and decoded thanks to years of work by today's guest. Jens Juul Holst is a Professor of Medical Physiology and Biomedical Sciences at the University of Copenhagen. His efforts laid the groundwork for today’s weight loss jabs, earning him a slew of high-profile accolades and awards. Now it seems they might not only have positive impacts on obesity and diabetes, but also other health issues... But alongside the big success comes some big questions: including concerns over side effects, weight regain post-treatment, the black market in such drugs, and their cost and accessibility. In a frank conversation with Professor Jim Al-Khalili, Jens address these issues and shares his hopes for the future of GLP-1-focused research.

It's a rare thing to encounter a medical specialist who has experience of his field from the expert and the patient perspective - but not unheard of...

Jim Ashworth-Beaumont is an orthotist and prosthetist who spent years helping people adapt to life with artificial limbs and musculoskeletal supports, before a near-fatal accident left him relying on both.

This twist of fate might have derailed many - but Jim drew on reserves of resilience and determination forged long before his accident; initially in the army, then by returning to education to earn the qualifications he missed out on as a youngster. He put himself through night school before earning a place to study Prosthetics and Orthotics at the University of Strathclyde. Later, while working at London’s Royal National Orthopaedic Hospital, Jim completed a Master’s in Neurorehabilitation, and a PhD in Health Studies – driven by a fascination with how the human body adapts under pressure.

But in 2020, while training for a triathlon, Jim was involved in a catastrophic cycling accident that nearly killed him - and cost him an arm. He tells Jim Al-Khalili how the incident gave him a whole new insight into his patients’ experience and made him more determined than ever to achieve his goals.

Presented by Jim Al-Khalili Produced by Lucy Taylor

“I shall largely speak of mice,” the paper begins “but my thoughts are on man.”

So begins a truly extraordinary scientific paper, and an equally extraordinary story.

“Death Squared: The Explosive Growth and Demise of a Mouse Population.” was published in 1973 by John Calhoun, and it detailed his increasingly bizarre research into the psychological effects of overcrowding. Over two decades he built a series of ‘rodent utopias’, where he could keep a population of rats or mice, meet all their basic food and shelter needs, but mess around with population levels. He wanted to see how they responded to having to live, cheek-by-tiny-jowl, with far more other rats than they were used to. And it wasn’t pretty. Social orders melted into chaos, rodents fought indiscriminately, or shut themselves away at the top of the enclosure. Mating orders collapsed, population numbers tanked, and eventually, every single rat was dead.

His work came at a prescient time. In the 60s and 70s, the exponentially expanding human population was a hot-button topic, and ‘population panic’ was in full swing. Alongside the expansion of cities, creeping urban sprawl, rising city-centre crime rates and 'urban sinks', there grew a concern that human living conditions were about to take an interminable dive. How would we live, with so many of us on earth? Calhoun’s work was leapt on by the press and public as a dire prediction of our own coming collapse. His rodent utopias became a subject of great interest among architects and city planners, psychologists and sociologists, and anyone fascinated by the human condition. But has his work been misunderstood?

50 years on, what lessons can we take from the work of a ground-breaking but often misunderstood scientist, in the face of a human population now exceeding 8 billion. Emily Knight explores his extraordinary work, its implications for humanity, and the possibility of a human utopia, that might not look anything like you expect.

Presented and Produced by Emily Knight in Cardiff