Peter J. Richerson is a Distinguished Professor Emeritus in the Department of Environmental Science and Policy at the University of California—Davis. His research focuses on the processes of cultural evolution. His 1985 book with Robert Boyd, Culture and the Evolutionary Process, applied the mathematical tools used by organic evolutionists to study a number of basic problems in human cultural evolution. His 2005 book with Boyd, Not By Genes Alone: How Culture Transformed Human Evolution, is an introduction to cultural evolution aimed at a broad audience. His recent publications try to understand some of the main events in human evolution, such as the evolution of the advanced capacity for imitation that makes possible our complex languages, technologies and societies, the origins of agriculture, and the evolution of modern behavior.