Competing through Co-operation in Nonhuman Primates: Developmental Aspects of Matrilineal Dominance

This paper's major aim is to illustrate how competition and co-operation are causally interrelated in the social life of nonhuman primates. In many species, competition for resources and mates commonly leads to xenophobic alliances and to the formation of intra-group dominance orders in which coalitions and alliances play a major role. In this sense, competition fosters co-operation. After briefly reviewing the nature of alliances in primates, this paper focuses on matrilineal dominance systems, which characterise many species of the Cercopithecidae family (macaques, baboons, etc.). In these societies, females socially inherit their mother's rank above lower-ranking matrilines with the result that kin rank next to each other. This paper summarises 10 years of experimental research on the composition and dynamics of alliances in a captive group of Japanese macaques (Macacafuscata). The main experimental paradigm consisted in manipulating the composition of the group, thereby dismantling existing alliances and inducing the formation of new alliances and new rank orders. Results reveal the existence of a complex interplay of kin and nonkin alliances responsible for the acquisition of rank and, later, for the maintenance of rank relations within and between kin groups. Opportunistic, selfishly motivated interventions in conflicts, performed by juveniles sharing the same targets (common targeting principle), appear to account for the initial formation of alliances in these dominance systems and, possibly, in various other situations as well. Such relatively simple processes may have paved the way for ontogenetically and phylogenetically more sophisticated forms of co-operation, such as reciprocity involving delayed benefits to the donors.