The Sex Contract: The Evolution of Human Behavior

adolescent adult Ambrona ancestors ancient animals anthropologists apes Australopithecus baboons became began begun behavior boisei bond bones brain called camp carry chewing child chimpanzee chimps cooperation copulate creature cubic centimeters cycle dominant Dryopithecus early East Africa elephants estrus evolution evolved female protohominid forest fossils friends genetic genitals gestures Gombe gorillas grass groom gully hippos hominids Homo erectus Homo habilis Hoot human female human language hunting incest individuals infant kill kinship knew lake Lake Turkana larger learned lived looked Louis Leakey Lucy males Mary Leakey mate meat million years ago modern monkeys months mother Olduvai Olduwan orangutans orgasm ovulation Perhaps period of heat picked Piltdown primate probably protohominids Ramapithecus Richard Leakey roamed savannah scientists sex contract sexual shamanic share skull social sociobiology soon sounds species stick survive teeth tiny trees vegetables walked women woodlands words young