The adaptive value of male relationships in the chimpanzees of Gombe National Park, Tanzania

Joseph Feldblum, Duke Evolutionary Anthropology and Graduate Fellow at Kenan Institute for Ethics
In many species of non-human primates, males form friendly social bonds while simultaneously competing with each other for high rank in a dominance hierarchy that determines mating access to females. While studies reveal a clear link between female bonds and fitness in several primate species, few studies have investigated such a relationship in males. Here, we investigate whether male social bonds, or position in cooperative networks, facilitate fitness benefits in one population of wild, free-ranging chimpanzees. We find that rank change was associated with social connectedness and betweenness in the network of coalition formation, but not with betweenness in the network of social relationships. Surprisingly, reproductive success was not associated with social connectedness or betweenness in coalitionary or social relationship networks, but grooming patterns strongly predicted reproductive success. Thus it appears that males who rise in rank have stronger bonds with group-mates, are central in the network of coalition formation, and groom others at a high rate (if they are low-ranking to begin with). However, males that successfully sire offspring are only those that groom others at a high rate. I will discuss the implication of these results for the applicability of social network analysis to the study of animal behavior.
February, 20 2017 | 12:45 p.m. - 2:00 p.m. | Gross Hall 230E

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