Archived Abstracts
Targeting or supporting, what drives patterns of aggressive intervention in fights?
Authors: Ivan Puga-Gonzalez, Matthew A. Cooper, Charlotte, K. Hemelrijk
During an aggressive intervention in a dyadic fight, the intervening individual provides not only support to one of the opponents but also intervenes contra the other. Hypotheses regarding the distribution of aggressive interventions emphasize the benefit of support (e.g. in the theory of reciprocal altruism) over the harm of contra-intervention. In this study based on an individual-based model, GrooFiWorld, we focus on the identity of the individual who receives contra-intervention rather than support. We test the model’s predictions in empirical data of a group of bonnet macaques (Macaca radiata). GrooFiWorld is a model of social interactions in which individuals either attack or groom others in their proximity. Individuals are likely to attack a neighbor if their probability of defeating it is high, otherwise they may groom it. Patterns of reciprocation and exchange of grooming and support that emerge in the model resemble those reported in primates. However, in the model individuals also receive more contra-intervention from those whom they groom more frequently. Although such interchange seems at odds with the theory of reciprocal altruism, we confirm it in adult female bonnet macaques: they directed more contra-intervention to those from whom they received grooming more frequently. Further, they received more contra-intervention from higher ranking females. Thus, contra-intervention was directed down the dominance hierarchy. These findings are consistent with predictions from the model and suggest that the distribution of aggressive interventions may be driven more by the identity of the individual being contra-intervened than by the identity of the individual being supported.
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