Social Structure, Robustness, and Policing Cost in a Cognitively Sophisticated Species

Abstract

Conflict management is one of the primary requirements for social complexity. Of the many forms of conflict management, one of the rarest and most interesting is third-party policing, or intervening impartially to control conflict. Third-party policing should be hard to evolve because policers personally pay a cost for intervening, while the benefits are diffused over the whole group. In this study we investigate the incidence and costs of policing in a primate society. We report quantitative evidence of non-kin policing in the nonhuman primate, the pigtailed macaque. We find that policing is effective at reducing the intensity of or terminating conflict when performed by the most powerful individuals. We define a measure, social power consensus, that predicts effective low-cost interventions by powerful individuals and ineffective, relatively costly interventions by low-power individuals. Finally, we develop a simple probabilistic model to explore whether the degree to which policing can effectively reduce the societal cost of conflict is dependent on variance in the distribution of power. Our data and simple model suggest that third-party policing effectiveness and cost are dependent on power structure and might emerge only in societies with high variance in power.

Context modulates signal meaning in primate communication

“…The implications of being able to communicate about a pattern of behavior, rather than only immediate behavior ¶ , extend beyond the development of higher quality dyadic relationships. The invention of signals communicating agreement to behavioral patterns, which change slowly (during this study there was only one relationship reversal over the course of 5 months), also appears to have influenced organizational complexity by allowing the emergence of power structures that change over relatively slow time scales (12,13). These temporally stable power structures support special forms of third-party conflict management that are advantageous at the group level (8,13,14).…”

“…The first is that higher-ranking individuals groom lower-ranking ones in return for SBTs, in which case there should be an asymmetry in the dyad in the distribution of grooming favoring the lowerranking partner. The logic underlying this hypothesis is individuals receiving many SBTs from many group members are perceived more powerful than individuals receiving few SBTs (12,13). Subordinate individuals differentially distribute SBTs over dominant partners, signaling repeatedly to some individuals and rarely to others.…”

“…Elsewhere (12) it has been shown that a temporally stable, highly predictive power structure arises from the network of peacefully exchanged signals. This power structure makes possible a particular type of conflict management that has systemic effects on organizational robustness by significantly changing the structure and complexity of social networks that constitute essential social resources in gregarious primate societies (8,13,14). The emergence of power structures that arise slowly from, and influence, rapidly changing individual-level interactions appears to depend on the capacity to communicate about a behavioral pattern, rather than just immediate behavior.…”

“…Because reconciliation is conditional on the occurrence of fighting, we controlled for individual variation in tendency to fight. We calculated the observed minus expected (o-e) frequency of reconciliation for each individual in each of its dyads given its total frequency of conflict, following a procedure from Flack et al (13) controlling for underlying variance in fight frequency. There was no effect of condition on mean o-e frequency of reconciliation (repeated measures: n ϭ 36, m P ϭ 0.42, SD ϭ 3.08; m NO ϭ Ϫ0.11, SD ϭ 1.38; m C ϭ Ϫ0.57, SD ϭ 0.82, SS ϭ 6.19; df ϭ 2; F ϭ 0.80; P Ͻ 0.45; partial eta 2 ϭ 0.02).…”

Individual Variation in Social Aggression and the Probability of Inheritance: Theory and a Field Test

“…Certain group members inflict or receive many more acts of aggression than others. In some cases, these acts (which include bites, shoves, mounts, and charges) appear to regulate cooperative activity in the group by activating lazy workers, for example, or punishing defectors (Reeve and Gamboa 1987;Reeve 1992;Mulder and Langmore 1993;Clutton-Brock and Parker 1995;Balshine-Earn et al 1998;Nonacs et al 2004;Bergmüller et al 2005;Flack et al 2005), but a large proportion of aggressive "dominance" interactions seem to be related to maintaining or challenging social status (Reeve 1991;Reeve and Sherman 1991;Reeve and Ratnieks 1993;Cant and Johnstone 2000). Relatively mild interactions may sometimes escalate into more costly fights in which the winner establishes dominance over, evicts, or even kills the loser (e.g., social insects : Waloff 1957;Gamboa et al 1978;Pollock and Rissing 1985;Heinze and Buschinger 1987;Balas and Adams 1996;vertebrates: Vehrencamp et al 1986;Pusey and Packer 1987;Zahavi 1990;Davies 1992;Clutton-Brock et al 1998).…”