This chapter presents a reconstruction of the way of life of Australopithecus, based on interpretations of new evidence and reinterpretation of the old. It explores the assumption that hunting arose early in human evolution and that meat was a primary food source. The chapter proposes that gathering of plant foods was the basic adaptation, and interprets social organization, parental investment, and mating patterns within this framework. The social life of early hominids was necessarily interrelated with their subsistence pattern. Molecular studies provide a valuable perspective on phylogeny, especially because of the skimpy fossil record for hominids and African apes during the crucial period of divergence between five and ten million years ago. Fossil hominids become abundant at the period referred to as the Plio-Pleistocene and by two million years ago there was a radiation of two or more species. Tool use as an essential part of hominid evolution interrelates with diet, bipedalism, and social behavior.