What Does Agonistic Dominance Imply in Bonobos?

Abstract

Social dominance is a relevant factor in the study of animal behavior, primatology in particular (Bernstein 1981, Walters and Seyfarth 1987, Newton-Fisher 2004). Social dominance is determined by repeated interactions between pairs of individuals, thus dyadic interactions are important in shaping the nature of the relationship (Hinde 1976). Given that social dominance allows each individual to resolve intragroup contests without engaging in energetically expensive, risky, agonistic interactions, the dominant individual (one with the higher probability of winning any contest) generally acquires the contested resource with only a minimum cost of time and energy, while the subordinate individual (one with the lower probability of winning) avoids wasting both time and energy in a contest that it is likely to lose anyway (Newton-Fisher 2004). Therefore, both individuals avoid potential injuries, which are expected to be greater for the subordinate. This view of dominance is generally based on agonistic interactions and is more precisely defined as agonistic dominance (Bernstein 1981, Walters and Seyfarth 1987, Drews 1993, Mason 1993). On the other hand, dominance style refers to the pattern of expressed asymmetry in agonistic relationships (de Waal 1989, de Waal and Luttrell 1989): it refers to how dominants treat subordinates and vice versa (de Waal 1996). Many studies have revealed dominance style in chimpanzees (Pan troglodytes), in which males are fairly linearly ranked, whereas females generally are not (Wittig and Boesch 2003). Our knowledge of dominance style in Pan paniscus, however, is still controversial (Hohmann and Fruth 2003, Paoli et al. 2006a).