Charles Darwin’s work had a profound influence on the study of human society, though in a much slower and more unreliable way than on non-human biology. His most important ideas about human society were not the ones that had the earliest and most visible impact. Rather than retell the familiar story of how ideas about heredity and the centrality of the competitive struggle came to dominate social science in the late 19th century, to be equally vigorously and uncritically repudiated in the 20th, this lecture will focus on a different lesson from Darwin. Our cousinship to other primates, and especially to great apes, has yielded real insights into the organization of human societies. We share many features with other primates, and we differ from them also in important ways besides the obvious ones. As well as summarizing what we can learn about human society from modern primate research, I shall ask how much of this would have surprised Darwin himself. The answer, which draws more on Darwin’s later books The Descent of Man and The Expression of the Emotions in Man and Animals than on The Origin of Species, is itself quite surprising. Darwin emerges as a man both astonishingly prescient and at times curiously in thrall to the preconceptions of his time.