The acquisition of rank and the development of reciprocal alliances among free-ranging immature baboons

Abstract

1. In many Old World monkey species, reproductive benefits accrue to high-ranking males and females. During 15 months' observation of the agonistic interactions of free-ranging juvenile and subadult baboons, most individuals assumed ranks similar to those of their mothers during disputes with their peers. Maternal intervention in the disputes of their offspring appeared to be the primary factor affecting the inheritance of rank. Both the rate and the relative success of maternal aiding behavior were correlated with maternal rank, and therefore tended to perpetuate the existing rank heirarchy across generations. 2. Although the ranks of immature animals depended on the ability of family members to support them successfully when threatened, immature animals formed aggressive alliances primarily with the members of highranking matrilines. In contrast, adult females in the study troop formed alliances primarily with probably related individuals of adjacent rank. A model is presented that attempts to explain ontogenetic changes in alliance formation on the basis of the potential costs and benefits of entering into aggressive alliances with particular indivuduals.