In this book, Jonathan H. Turner combines sociology, evolutionary biology, cladistic analysis from biology, and comparative neuroanatomy to examine human nature as inherited from common ancestors shared by humans and present-day great apes. Selection pressures altered this inherited legacy for the ancestors of humans—termed for being bipedal—and forced greater organization than extant great apes when the moved into open-country terrestrial habitats. The effects of these selection pressures increased hominin ancestors’ emotional capacities through greater social and group orientation. This shift, in turn, enabled further selection for a larger brain, articulated speech, and culture along the human line. Turner elaborates human nature as a series of overlapping complexes that are the outcome of the inherited legacy of great apes being fed through the transforming effects of a larger brain, speech, and culture. These complexes, he shows, can be understood as the cognitive complex, the psychological complex, the emotions complex, the interaction complex, and the community complex.