What’s behind the injectable peptide craze?

Grey-market injectable peptides – a category of substances with obscure, alphanumeric names such as BPC-157, GHK-Cu, or TB-500 – have developed a devoted following among biohackers and health optimisers. To understand how these unregulated substances have become mainstream and what they could be doing in our bodies, Madeleine Finlay hears from journalist Adrienne Matei and from Dr Anna Barnard, an associate professor at Imperial College London who researches peptides. Help support our independent journalism at theguardian.com/sciencepod

The Guardian’s science editor, Ian Sample, talks to Madeleine Finlay about three eye-catching science stories from the week, including a study that explores the link between exercise and brain health. Also on the agenda: the discovery that hedgehogs can hear high-frequency ultrasound and what this could mean for their conservation, and new research examining how biased AI autocomplete tools can influence the beliefs of users.. Help support our independent journalism at theguardian.com/sciencepod

Among the many justifications Donald Trump has presented for the US and Israel attacking Iran has been the supposedly imminent threat posed by its nuclear weapons programme. But how close was the country really to developing an atomic weapon? Ian Sample hears from Kelsey Davenport, the director of non-proliferation policy at the Arms Control Association. She sets out why many experts don’t believe the country even had a structured nuclear weapons programme, and explains what she thinks the impact of the war could be on nuclear proliferation around the world.. Help support our independent journalism at theguardian.com/sciencepod

The conflict in the Middle East has sent energy prices soaring, and for countries that import a high proportion of their fuel, it’s a reminder of the perils of energy dependence. As the recipient of almost 90% of Iran’s crude oil, China knows this only too well. Which partly explains why the country spent the last decade heavily investing in clean power. To find out what else could be driving the strategy, Madeleine Finlay speaks to senior China correspondent Amy Hawkins. And energy correspondent Jillian Ambrose reflects on how China’s ambitions could affect the rest of the world. Help support our independent journalism at theguardian.com/sciencepod

In the past three months, Donald Trump’s White House has reportedly used AI twice to effect regime change – once in its capture of Venezuela’s president, Nicolás Maduro, and more recently to help plan the strikes that killed Iran’s supreme leader, Ayatollah Ali Khamenei. The most recent strikes coincided with the end of the Pentagon’s relationship with the AI company Anthropic over concerns its AI tool Claude was being used for purposes the company had explicitly prohibited. The government swiftly signed a new contract with Open AI. To find out what this means for the use of AI in forthcoming conflicts, Madeleine Finlay speaks to technology journalist Chris Stokel-Walker. He explains why he thinks this moment represents a dangerous turning point.. Help support our independent journalism at theguardian.com/sciencepod

Since the 1960s, global GDP has been rapidly rising and living standards have reached record highs. But something else has been rocketing up too – carbon emissions. For years, scientists and economists have been asking: is it possible to grow without heating and polluting the Earth? And as the climate becomes more unstable, the issue is only becoming more urgent. Madeleine Finlay hears from two economists arguing for a change in how we measure a country’s success. Nick Stern is professor of economics and government at the London School of Economics and an advocate of green growth, an approach to growth that prioritises green industry. Jason Hickel is a political economist and professor at the Autonomous University of Barcelona who advocates degrowth, shrinking parts of the economy that do not advance our social and ecological goals.. Help support our independent journalism at theguardian.com/sciencepod

For a long time fat was seen simply as an inert yellow substance wrapping around our bodies, but now that’s changing. Scientists are beginning to understand that our fat is actually intricate and dynamic, constantly in conversation with the rest of the body. It’s now even considered by some to be an organ in its own right. To find out more about the complex role fat plays in our health, Ian Sample hears from co-host Madeleine Finlay and from Declan O’Regan, professor of cardiovascular AI at Imperial College London. Help support our independent journalism at theguardian.com/sciencepod

Madeleine Finlay sits down with science editor Ian Sample and science correspondent Nicola Davis to discuss three eye-catching stories, including the impact of a powerful psychedelic on depression, answers on the death of Russian opposition leader Alexei Navalny, and an explanation to the mystery of why humans have chins. Help support our independent journalism at theguardian.com/sciencepod

Testimonials about the beneficial health effects of magnesium supplements abound online, with influencers claiming that a daily pill can help with everything from anxiety to sleep and brain fog. But do any of these claims stack up? Ian Sample is joined by co-host Madeleine Finlay to find out where the science stands. They also hear from Katherine Tucker, the founder of the Center for Population Health at the University of Massachusetts Lowell. She explains what magnesium is doing in our bodies and the best approach we can take to ensure we are getting enough. Help support our independent journalism at theguardian.com/sciencepod

In late January a new social media site took a certain corner of the internet by storm. Moltbook was conceived as a space where AI assistants could let off steam, chat and compare notes on their bosses, but it quickly became the focus of breathless claims that the singularity had arrived as the bots started badmouthing their humans and plotting an uprising. So what’s the truth about Moltbook? Madeleine Finlay hears from Aisha Down about what it tells us about AI, and about us.. Help support our independent journalism at theguardian.com/sciencepod