Antiquity and Social Functions of Multilevel Social Organization Among Human Hunter-Gatherers.

Three levels of social organization are recognized among human hunter-gatherers: the community, the domestic unit, and the band. We describe the key features of these three levels and show how they are intimately connected. We hypothesize that, in the course of human social evolution, bands emerged as a level of social organization within existing communities. As predators, hunter-gatherers live at lower population densities than chimpanzees ( Pan troglodytes), even where the two species are sympatric. We propose that band formation evolved in humans from the more transient fissioning behavior seen within chimpanzee communities as a solution to the conflicting pressures of sustaining higher levels of cooperation required in hunting and the division of labor in a more dispersed community. If disputes break out, or if resources in the band territory are temporarily depleted, the existence of a wider community continues to be adaptive. To reconstruct the evolution of band society, we draw upon four lines of evidence: group (or network) size predicted from neocortex ratios, the distance materials were moved from their source during various periods in hominin evolution, ethnographic data on hunter-gatherer daily foraging ranges and population densities collated by the authors, and fossil hominin morphology. From these data, we conclude that key features of modern human hunter-gatherer social organization probably appear in the course of the evolution of Homo heidelbergensis. [ABSTRACT FROM AUTHOR]