Conflicts and their resolutions in chimpanzees: exploring the contribution of relationship value and signals of benign intent

Conflicts are a perennial issue for gregarious animals and the stability of their groups. Reconciliation can mitigate the damage caused by conflicts. Chimpanzees provide an ideal model animal for understanding conflicts and their resolutions, due to both their high aggressiveness and large fission-fusion communities, which regularly split into smaller groups of different compositions. Different mechanisms have been proposed to explain their reconciliation behaviour, with the valuable relationship hypothesis receiving frequent empirical support – namely, chimpanzees with stronger social bonds are more likely to reconcile after a conflict. Despite its success, it is nonetheless insufficient to explain the large variability which is often observed in conciliatory tendencies. The benign intent hypothesis predicts that non-contact affiliative behaviours function to facilitate reconciliation and together with relationship value, these signals may help explain variation in conciliatory tendencies. Hence, this matched-control study investigated both hypotheses in a group of captive chimpanzees. While sex affected conciliatory tendencies, particularly valuable male–male relationships were not observed to reconcile more often than male–male dyads. By contrast, former combatants with a higher association index, a more detailed measure of relationship quality, were more likely to reconcile than those with a lower index. Signals of benign intent, although rarely displayed, were consistent with facilitating reconciliation. Namely, hold-out-hand was observed only after conflicts and before reconciliation. Importantly, these signals were displayed between individuals of different association scores, suggesting that both hypotheses have explanatory power and may interact. Rather than being explained by a single hypothesis, chimpanzee conciliatory tendencies likely result from the interaction of complementary mechanisms.