Alliances as a means of competition in primates: Evolutionary, developmental, and cognitive aspects

Nonhuman primates commonly compete for mates, physical resources and dominance status. Competition is manifest in one-to-one contests or in more complex, multipartite aggressive interactions involving the formation of alliances. In this paper, five aspects of competitive alliances are reviewed: 1) the evolutionary and ecological conditions favoring the occurrence of alliances among females, among males, and between males and females, 2) the dynamics of the three main categories of competitive alliances, called bridging, revolutionary, and conservative, 3) the developmental processes that may account for the initial formation of alliances, 4) the cognitive abilities involved in two major aspects of alliances, the recognition of one's allies and of the allies of other individuals, and 5) the value of functional explanations of alliance behavior, namely kin selection, reciprocal altruism and mutualism.