Local objects, distant symbols: Fission-fusion social systems and the evolution of human cognition

© Cambridge University Press 2015. Relative to other primates, modern humans live social lives of remarkable complexity, maintaining relationships with other individuals over entire life-spans and across continental divides. The spatio-temporal scales over which we interact define our society and highlight a marked break from other species. Nevertheless, there is clear evidence among some apes and monkeys of social systems that could be considered antecedent, or informative parallels, to our own. One such social system is characterised by the repeated division and aggregation of smaller groups into larger groups (termed ‘fission-fusion’: Kummer 1971). This apparently simple system is highly beneficial ecologically, yet leads to profound social and cognitive pressures. This paper will argue that these cognitive demands have played a considerable role in shaping the evolution of specific aspects of modern human cognition. Gamble’s (1993, 1996a, 1998a, 1999) network approach to Palaeolithic society, particularly as part of the British Academy’s Archaeology of the Social Brain project, has facilitated the comparison of the social systems of extant primates, modern hunter-gatherers and archaeologically documented populations within a single framework. This links group size during prehistory to social complexity; social complexity as a whole is constrained by cognitive capacity, measured primarily by the relativesize of the neocortex; and fission-fusion is an important signifier of social complexity, linking not only to a number of specific cognitive abilities but also to neocortical ratios in primates. We here combine Gamble’s notion of the increasing scale of Palaeolithic life with a particular concern with the cognitive ramifications of stretching fission-fusion social organisation beyond the limits seen in extant primates. To this end, the following sections define and examine fission-fusion as a social system, survey work on the modern human fission-fusion system, introduce research on a number of cognitive abilities that may be tied specifically to this system, and discuss the evidence for those cognitive abilities (and for fission-fusion directly) in thearchaeological record of the Palaeolithic.