The form and function of post-conflict interactions between female baboons

In many primate species, former opponents engage in friendly behaviours after aggressive conflicts. These kinds of interactions are labelled reconciliation because they are thought to repair relationships damaged by conflicts and help to preserve group cohesion. This study assessed the form and function of reconciliation between free-ranging female baboons, Papio cynocephalus ursinus, in the Okavango Delta of Botswana. The rate of interaction between former opponents was higher during the minutes that followed conflicts than in the days that preceded or followed conflicts. Baboons reconciled vocally, grunting quietly to their former opponents after conflicts ended. Grunts after conflicts facilitated infant handling. Females were particularly likely to reconcile with highranking opponents, the mothers of young infants and related mothers of older infants. Reconciliation had no consistent effect upon the rate of interactions during the days that followed conflicts. This study is the first to demonstrate that primates reconcile vocally and the first to assess the long-term consequences of reconcilation in a naturalistic setting. ? 1996 The Association for the Study of Animal Behaviour Monkeys and apes tend to approach and interact non-aggressively with their former opponents at much higher rates immediately after conflicts than at other times. De Waal (1986) first suggested that peaceful contacts after conflicts are a form of reconciliation that enable former opponents to resolve conflicts and repair social relationships damaged by conflict. Although reconciliation has been most systematically studied and widely documented among primates (reviewed by Kappeler & van Schaik 1992), anecdotal accounts of reconciliation also exist for a handful of other taxa (Cords & Thurnheer 1993). Indeed, if reconciliation does serve to resolve conflicts and repair relationships damaged by conflict, then we might expect it to be common in species that form stable and cohesive social groups. Most analyses of reconciliation behaviour have focused upon the form and frequency of events after conflicts; only three have evaluated the actual consequences of post-conflict affiliative behaviours for the participants. In long-tailed macaques,Macaca fasicularis, the rate of scratching, body shaking and self-grooming by victims increases after conflicts, a sign that victims experience higher levels of sympathetic arousal after conflicts than they do at other times (Aureli et al. 1989; Aureli & van Schaik 1991). The rate of these behaviour patterns declines more quickly to baseline levels, however, if opponents reconcile than if they do not do so. This result suggests that reconciliation relieves the victims’ stress after conflicts. Reconciliation also reduces the probability that the former aggressor will resume its attack upon the victim (Aureli & van Schaik 1991). Cords (1993) artificially provoked conflicts between pairs of juveniles in another captive group of long-tailed macaques and evaluated the effect of reconciliation upon the latency to resume drinking in close proximity. She found that reconciliation significantly reduced the time the subordinate took to resume drinking near the dominant partner and reduced the probability that further attacks would occur. In Correspondence: J. B. Silk, Department of Anthropology, University of California, Los Angeles, CA 90095, U.S.A. (email: [email protected]). D. L. Cheney and R. M. Seyfarth are at the University of Pennsylvania, Philadelphia, PA 19104, U.S.A. 0003–3472/96/020259+10 $18.00/0 ? 1996 The Association for the Study of Animal Behaviour