"Human nature" has meant many things to many people. Why do we do what we do? Before 1859, when Darwin published The Origin of Species, the meaning of "human nature" was anybody's guess. This book collects the first, classic tests of Darwinian theory on us -- including studies of traditional societies (from the !Kung of Botswana to the Ache of Paraguay), studies of modern societies (from Hamilton, Ontario, Canada to southern California), and comparative and historical studies (from the ancient Near East to imperial Rome). These classics are interspersed with new critiques -- both by the authors themselves, and by biologists who used modern Darwinian theory to pioneer field studies, cognitive studies, and comparative studies of other species. Last but not least, Human Nature adds an introduction which covers the basics in evolutionary theory, and reviews cutting-edge tests of that theory on human anatomy, physiology, emotions, thought, and interactions. This pathbreaking book collects the best of the first tests of Darwinian theory on humans, critiques them, and comprehensively reviews the work being done now. It is an ideal - and long needed - text for courses in biology, anthropology, sociology, psychology, economics, history, and philosophy which use Darwin's theory to explain what we do and who we are.