In this episode, Patrick is joined by Alex Cagan, a Postdoctoral Fellow in the Cancer, Ageing and Somatic Mutation programme at the Wellcome Sanger Institute, specialising in evolutionary processes in somatic tissue. Tune in as Alex walks us through a fascinating new study, years in the making, looking at somatic mutation rates across 16 mammalian species, spanning 30-fold in lifespan and around 40,000-fold in body mass. This work sheds light on fundamental questions in cancer and ageing across the tree of life.

0:00 Intro

6:00 Collaborating with the London Zoo, and the challenges of sourcing tissue from long-living animals

9:06 Why are naked mole rats so important to the cancer and ageing community?

11:32 The scale and breadth of species sampled in the study

14:53 Is there a ceiling to how many mutations an organism can tolerate?

17:53 Why are intestinal crypts so effective for sequencing somatic mutations?

20:44 Key learnings from driving a 5-year study into somatic evolution

22:46 Are there really any “immortal” species, and what are they?

25:19 Why are cancer rates lower in larger species, and is this related to lower mutation rates, DNA error correction or both?

27:24 Investigating transmissible cancers in Chernobyl

29:40 Is cancer everywhere in the tree of life?

31:23 Alex talks about applying his talent for illustration to science

38:56 The Sanger Tree of Life program, the Darwin Tree of Life project, and the bright future ahead for research on somatic mutations

40:14 Outro

Find out more about the study: https://www.nature.com/articles/s41586-022-04618-z