AGGRESSIVE AND PEACEFUL INTERVENTIONS IN CONFLICTS IN TONKEAN MACAQUES

Peaceful interventions in conflicts are an extremely rare phenomenon i n most primate species. In contrast to aggressive interventions, they cannot lead to gains in terms of competition. To clarify the function and origin of this behaviour, the patterning and consequences of peace ful and aggressive interventions were studied in a semi-free ranging g roup of tonkean macaques, Macaca tonkeana. Intense conflicts frequentl y elicited both types of intervention. Interveners preferentially targ eted the initiator of the conflict, who was generally the dominant of the two opponents. Males tended to intervene more than females, especi ally using peaceful interventions. Interventions were frequently perfo rmed on behalf of the most closely kin-related opponent; this was true particularly for aggressive interventions. In peaceful interventions, the intervener was usually dominant over both parties. Lipsmacking, c lasping, mounting and social play were mainly used, and were successfu l in halting aggression. Peaceful interventions were frequently follow ed by an affinitive interaction, such as grooming, between intervener and target. Peaceful interventions thus appear to protect the benefici ary while preserving the social relationship between intervener and ta rget. The origin of the behaviour can be traced to the epigenetic cons traints arising from the species-specific social organization.