Proximate Mechanisms Underlying Primates’ Complex Social Networks
Résumé
The proximate mechanisms giving rise to reciprocation and interchange of social behaviours in primates have been extensively debated. Three mechanisms have been proposed: “calculated reciprocity,” “emotional bookkeeping” and “symmetry-based reciprocity”. Based on experimental and observational data, researchers appear to favour emotional bookkeeping. A different approach to study potential mechanisms underlying reciprocation and interchange is by means of individual-based computer models. Three models, identical regarding the rules for individuals’ social interactions, suggest mechanisms resembling “symmetry-based reciprocity” and “emotional bookkeeping” as the basis of reciprocation and interchange. “GrooFiWorld” suggests proximity-based interactions; “FriendsWorld” suggests proximity-based interactions and preferential interactions; the “Reaper model” suggests preferential interactions alone. Because the three models reproduce reciprocation and interchange, it is difficult to tell which one, if any, more accurately represents the empirical data. To clarify this, here we used a social network approach. We collected data from six captive and eight wild/provisioned groups belonging to eight macaque species and did a social network analysis. Then, we simulated each group in each model, analyzed the emergent social networks, and quantitatively compared empirical and models’ networks. Results show that the three models capture to some degree the features observed in social networks of macaques. However, no model seems better than the others at fitting the observed data. Further, modularity, average eigenvector centrality, and degree of network centralization were poorly fit by all models. Social interactions in the models thus may be more simplistic than in reality and may miss some mechanism(s), e.g. accounting for third-party relationships. We will, in the future, study whether implementing this or other mechanisms may improve the fit between models and the empirical data.