Social Network Dynamics of Female Chacma Baboons

Social structure is the product of the costs and benefits of group living. Dyadic social bonds in female chacma baboons are strong and long-standing, conferring fitness benefits upon both individuals while contributing to a greater social structure. Longitudinal grooming data collected from 2001-2007 from Moremi Game Reserve, Botswana, illuminate social network dynamics of 50 female chacma baboons. Utilizing social network analysis (SNA), we analyzed social structure above the level of the dyad to see if attribute data (age, rank, and number of close female kin) was predictive of network location. Our SNA data was longitudinal, unbalanced, and continuous. We therefore used linear mixed-effects models (LMEs) and respective AIC/BIC values to choose the most likely predictive attributes for each SNA metric. From the chosen LMEs, rank was present most often. High rank predicted a higher frequency of outward grooming, an overall lower number of grooming partners, and a less extensive social network. It appears that high-ranking females have a fewer number of social bonds than low-ranking females, but that they are stronger. Considering that enduring social bonds result in increased offspring longevity, future studies include examining the potential adaptive value of weak, transient, more numerous social bonds.