Although group living is thought to be an adaptive strategy, it also inevitably leads to conflict of interests between group members. This is commonly due to competition for access to limited resources, such as mates or food. Conflicts of interest may escalate into aggression and may compromise the benefits of group living. It has been argued that in order to mitigate the negative effects of within-group conflicts, prevent aggression and resolve disputes, selection must have favored peacekeeping mechanisms in group-living animals. Many of these behavioral strategies are thought to operate soon after the conflict and involve affiliative interactions between former opponents and/or third-parties.
For more than 10 years detailed data of social interactions has been recorded on the chimpanzee colonys of Yerkes National Primate Research Center, and thousands of agonistic incidents have been collected. The existing behavioral database provides a unique opportunity to evaluate the contribution of different variables in the modulation of the expression of post-conflict behaviors, which could provide valuable insights into its proximate mechanisms.