Mirta Galesic: Santa Fe Institute

The importance and scale of cooperation in human societies is unmatched among other primates and is considered to be a major contributor to our species’ exceptional success. Given that cooperation seems so useful, it is surprising that it flourished only in humans but not in other primates who had similar cognitive abilities as our ancestors or lived in similar circumstances. Large-scale human cooperation is successfully explained by models of cultural group selection, but these models require a relatively advanced social cognition already in place. To explain early origins of human social cognition and cooperation, cooperative breeding and cooperative foraging accounts have been proposed. However, computational models of these accounts that would enable more precise understanding of the underlying mechanisms are still scarce.

We develop a computational model of one possible mechanism underlying the early development of human cooperation, based on interdependence. We show that the interdependence might have increased because several otherwise non-remarkable and ubiquitous factors came together for our early ancestors: specific physical properties of Early Pleistocene environments, characteristics of our early ancestors’ social structure, and their cognitive abilities. Together, these factors might have led to increased value of group foraging, which in turn led to increased interdependence, and eventually to higher propensity to share food with non-kin. This propensity could have been instrumental for the development of further prosocial tendencies, ultimately paving the way for the development of large-scale cooperation through cultural group selection, emerging in Middle and Late Pleistocene.