Captive chimpanzees share diminishing resources

Wild chimpanzees routinely share high-value resources such as meat obtained through hunting and fruit procured from raiding crops. Although it is predicted that the proximate mechanisms for sharing behaviour are the result of reciprocity, interchange and mutualism, examinations of these factors in captivity have not mirrored the degree to which they are found in the wild. The goal of the current study was to investigate how a group of seven captive chimpanzees responded when a highly desirable and monopolizable resource diminished over the course of eight months. To do this we measured the amount of time that was spent sharing food at an artificial termite mound as well as the relationship between dyads that spent time sharing. Our results contradicted our predictions that rates of aggression would increase and the number of individuals fishing at the termite mound would decrease when resources diminished, as we observed no difference in either variable over time. We did, though, find an increase in the amount of sharing as the number of baited holes decreased. We also found a correlation between the strength of dyadic relationships outside of the study and the amount of time that individuals spent sharing with each other.