(BEC) Adrian Jaeggi "Food sharing in human and non-human primates"
Food sharing is a vibrant field of study that has provided important insights into the evolution of cooperation, life history, and social learning. Common functional explanations for sharing include nutritional and informational benefits to offspring, tolerated scrounging, kin selection, reciprocal altruism, and costly signaling. I review the most important findings regarding food sharing in primatology and human behavioral ecology and sketch out the phylogenetic history of these functions. I draw attention to aspects of primate and human food sharing that are sometimes underappreciated but carry important implications for understanding evolved life history and the psychology of pro-sociality: Shared foods comprise a negligible part of the diet in most primates, contrasting with the obligatory provisioning of multiple dependent offspring by several caretakers in callitrichids and humans. Slow growth, delayed juvenility and heavy provisioning lead to extended periods of net consumption in human families and a resulting dependence on between-family sharing. Food transfers both within and between families are therefore an integral part of human life history which has likely been facilitated by the extended kin networks of humans compared to that of a chimpanzee-like ancestor. The negotiation of sharing norms in relation to different production regimes, and the strategic use of sharing as a costly signal are key components of human exchange relations. On the other hand, sharing among adult primates is best understood as an occasional manifestation of long-term social relationships within which services like grooming, selective mating, and coalitionary support are exchanged more routinely. These functional differences may explain why sharing among primates is predominantly passive, whereas humans seem to have evolved a more active sharing psychology.