In Social Transformations: A General Theory of Historical Development Stephen K. Sanderson develops a general theory of social evolution and uses it to explain the most important evolutionary transformations in human history and prehistory. In this expanded edition Sanderson has added a discussion of the biological constraints acting on humans that have helped to push social evolution along strikingly similar lines throughout the world. The new discussion places the theoretical arguments of Social Transformations in the context of an even more comprehensive theory of human social behavior.