This chapter explores biological perspectives on human behaviour and institutions, beginning with sociobiology and its derivations, including evolutionary psychology (EP). It details EP’s fundamental principles, proposed by Cosmides and Tooby, which posit that the human mind comprises specialised cognitive modules, designed by natural selection to solve adaptive problems faced by our hunter-gatherer ancestors. This perspective challenges the notion of the mind as a ‘blank slate’, suggesting that our ‘Stone Age minds’ still influence modern behaviour. The chapter then addresses John Dupré’s significant critiques concerning EP’s evidence, explanatory scope, the concept of ‘atavism’, and its reductionism regarding the mind’s social dependence. Finally, it examines EP’s application to law, demonstrating how ancestral moral heuristics shape intuitions on resource sharing, collective action and punishment, often leading to unintended consequences in complex modern legal systems. It proposes that EP illuminates law’s intrinsic function, while economic analysis explains its instrumental role, suggesting that law emerges from biological, social and individual evolutionary processes.