Building Strong Bonds in Baboons: Patterns, Mechanisms, and Adaptive Outcomes (#1)
Sociality has evolved in many animal taxa, and presumably reflects a balance between the benefits of living in groups (such as lower risk of predation) and costs (higher rates of competition over resources). Selection is expected to favor traits that enable individuals to increase the benefit/cost ratio. The formation of close social bonds among female baboons may be favored as a means of increasing b/c ratios. In some primate species, strong affiliative ties are linked to coalitionary success and the ability to acquire high ranking positions in the dominance hierarchy. Data from two different long-term studies of baboons show that females form strong, equitable, supportive, tolerant, and stable social relationships with selected partners, particularly close maternal kin and peers. Close social bonds help female baboons to cope with various sources of stress. In addition, females with close social bonds have higher survival among their offspring and live longer than other females. These findings suggest that close social bonds may provide a means for females to increase the b/c ratio of group life. However, to form these bonds, females must overcome barriers that keep them apart---the risk of conflict. Work on baboons suggests that they use grunts to communicate peaceful intentions. Grunts facilitate proximity and affiliation, reconcile aggressive conflicts, and relieve anxiety. Thus, these signals may provide an important link between the benefits of social bonds and the risks inherent in interacting with potential competitors.