The past decade has seen an upsurge of interest in the application of evolutionary thinking to the study of human behavior. This introductory book provides an overview of the key theoretical principles of human sociobiology and evolutionary psychology and shows how they illuminate the ways humans think and behave. The book takes as one of its main premises the idea that we think, feel, and act in ways that once enhanced the reproductive success of our ancestors. The book covers fundamental issues such as the origins and function of sexual reproduction, mating behavior, human mate choice, patterns of violence in families, altruistic behavior, the evolution of brain size and the origins of language, the modular mind, and the relationship between genes and culture. It also examines the larger implications of Darwinism for how we view ourselves as a species and our sense of ourselves as a moral animal. The book includes a valuable historical introduction to evolutionary theories of behavior and concludes with an examination of the social and political ramifications of evolutionary thought. It contains numerous diagrams and illustrations, comprehensive references, summaries, and suggestions for further reading.