Reciprocity and beyond: Explaining meat transfers in savanna-dwelling chimpanzees at Fongoli, Senegal.

Abstract

To understand the function of food sharing among our early hominin ancestors, we can turn to our nonhuman primate relatives for insight. Here, we examined the function of meat sharing by Fongoli chimpanzees, a community of western chimpanzees (Pan troglodytes verus) in southeastern Sénégal. We tested three non-mutually exclusive hypotheses that have been used to explain patterns of food sharing: kin selection, generalized reciprocity, and meat-for-mating opportunities. We analyzed meat sharing events (n = 484) resulting from hunts, along with data on copulations, age-sex class, and kinship to determine which variables predict the likelihood of meat sharing during this study period (2006-2019). We found full or partial support for kin selection, direct reciprocity, and meat-for-mating-opportunities. However, the analyses reveal that reciprocity and a mother/offspring relationship were the strongest predictors of whether or not an individual shared meat. The results of this study emphasize the complexity of chimpanzee meat sharing behaviors, especially at a site where social tolerance offers increased opportunities for meat sharing by individuals other than dominant males. These findings can be placed in a referential model to inform hypotheses about the sensitivity of food sharing to environmental pressures, such as resource scarcity in savanna landscapes.