Speaker(s): Dr Jonathan Birch, Heikki Helanterä, Hannah Rubin | If evolution is a 'struggle for existence', why do we witness so much altruism in nature? From bacteria to baboons, the natural world is full of spectacular examples of organisms cooperating with one another. In the early 1960s, WD Hamilton changed the way we think about how such behaviour evolves, and his pioneering work kick-started a research programme now known as 'social evolution theory'. The Forum brings together a panel of biologists and philosophers of biology will discuss the legacy of Hamilton’s ideas, and the evolution of altruism in microbes, insects, humans, and the cells of our own bodies. Jonathan Birch is Assistant Professor of Philosophy at LSE and author of The Philosophy of Social Evolution. Heikki Helanterä is Group Leader in the Centre of Excellence in Biological Interactions at the University of Helsinki. Hannah Rubin is Postdoctoral Researcher in Theoretical Philosophy at the University of Groningen. Bryan Roberts (@SoulPhysics) is Associate Professor in the Department of Philosophy, Logic and Scientific Method at LSE.