Stephen K. Sanderson taught for 31 years in the department of sociology and anthropology at Indiana University of Pennsylvania; he is currently a visiting professor of sociology at the University of California-Riverside. He specializes in evolution and human behavior, sociological and anthropological theory, and long-term social evolution. He is author or editor of eleven books in seventeen editions, including The Evolution of Human Sociality: A Darwinian Conflict Perspective, Macrosociology: An Introduction to Human Societies, and World Societies. He a member of the American Anthropological Association, the Human Behavior and Evolution Society, and the International Society for Human Ethology.