BBC Inside Science

Home News Sport Weather iPlayer Sounds Bitesize CBeebies CBBC Food Home News Sport Business Technology Health Culture Arts Travel Earth Audio Video Live Use BBC.com or the new BBC App to listen to BBC podcasts, Radio 4 and the World Service outside the UK.Find out how to listen to other BBC stationsEpisode detailsRadio 4,·23 Jul 2026,·28 minsAvailable for 35 daysSecretary of Defence Pete Hegseth has announced that the US military will be screening military personnel aged 30 and older for testosterone deficiency. Those found with low testosterone levels will be offered voluntary hormone replacement therapy. The secretary says this is to ensure “a healthy, capable, and decisively dominant fighting force”. Tom Whipple is joined by Professor Joe Herbert from the University of Cambridge to discuss why jacking soldiers up with testosterone may or may not be the best idea. Marine Biologist Kathryn Ayres, from the non-profit organisation Beneath the Waves, describes a newly observed behaviour in orcas in which they collaboratively swim so hard into a dead sunfish it explodes. Is it a teachable moment for their young or is it just for fun? Finally, we have Kit Yates, our resident mathematician, to reassure Tom that although AI might one day actually kill us all, at least it can disprove an 87-year-old mathematics conjecture. Presenter: Tom Whipple Producer: Dan Welsh, Alex Mansfield, Imy Harper, Tabitha Taylor Buck Editor: Martin Smith Production Co-ordinator: Jana Bennett-HolesworthProgramme WebsiteMore episodes