1School of Environment & Life Sciences, University of Salford, Greater Manchester, UK, 2Department of Anthropology, University of Durham, UK
Saturday All day, Plaza Level
A distinctive feature of human evolution is the emergence of the band in human society. The band is an enduring fusion phase set within a wider pattern of fission–fusion social organisation, and lacks analogues in extant apes. It is, in effect, a durable social coalition of pair-bonded households embedded within the community. We investigate several lines of evidence in an attempt to pinpoint why and when bands crystallised in human evolution. Both brain size evolution and the evolution of the pair-bond appear intimately tied in this relationship. Our review revealed that an increased reliance on meat for caloric intake prompted changes to hunting and foraging strategies and, crucially, forced humans into living at lower population densities with new and different relationship demands. Brain size concomitantly increased. Solving the subsequent problem of maintaining non face-to-face long-distance relationships, and divergent close range ones, was achieved cognitively since cognitively-mediated behavioural flexibility is the least committing and fastest to evolve. We propose that ‘strong cognition’ (heavy mutual investment) was a product derived following the evolution of human pair-bonds. Extrapolating the pair-bond relationship to non-pair (i.e. band) partners ensured that bonds among the dispersed network of band members could be maintained in spite of potentially long periods of separation. We link the timing of these events to Homo heidelbergensis, common ancestor to H. neaderthalensis and H. sapiens, placing him as the most likely candidate for the stem hominin for band formation.