Why does low mood, and at extreme, depression, exist? What is its function? James Turner is a postdoctoral researcher at Umeå University. He completed his PhD in Philosophy in 2024 at the University of Sheffield; the title of his thesis was : Low mood: Evolution, Cognition and Disorder.He has a general research interest in cognitive science, evolutionary theory, and the philosophy of psychiatry. In particular, He is interested in the evolution of low mood, the nature of physical and psychological function and dysfunction, and recently he has been dabbling in the philosophy of AI.This podcast is financially supported by the Human Ecology Group of the Institute of Evolutionary Medicine at the University of Zurich.