Human Nature collects the first, classic, papers to test Darwinian theories on Homo sapiens. It offers new critiques for those classics, written both by the authors themselves, and by biologists who pioneered field studies, comparative studies, and cognitive studies on other species. And it adds a new introduction, reviewing cutting-edge work on human anatomy, physiology, emotions, cognition, and interaction. This is the first text to use our only theory of life - Darwin's - to explain what we do and who we are.