The value of social bonds

The primary goal of the proposed project is to document the development and structure of social relationships among wild olive baboons, Papio anubis, in an effort to evaluate the hypothesis that close social bonds or “friendships” have adaptive value for individuals. This proposal builds on previous work on yellow and chacma baboons conducted in Kenya and Botswana, which suggests that the quality of females’ social relationships influences their ability to cope with stress and their reproductive success.

  Project Details

Sociality reflects a compromise between the benefits and costs of living in social groups, and natural selection is expected to to favor strategies than enable individuals to maximize their own benefit/cost ratios. This could lead to selection for more efficient foraging techniques or better predator detection. It might also favor the capacity to develop social strategies that enable individuals to compete more effectively with rivals or cope better with the costs of conflict. In many animals, competition for resources is linked to emergence of dominance hierarchies, and high rank enhances access to resources, such as food, water, mates and safe positions, and is often correlated with long-term reproductive success in both sexes.

However, the magnitude of the effect of dominance rank varies considerably across species within the primate order and within groups over time. Female baboons form stable linear dominance hierarchies in which related females occupy adjacent ranks, but dominance rank has a relatively small effect on female reproductive success (reviewed in Cheney et al 2004; Strum 2012).

Recent work on yellow baboons, Papio cynocephalus, and chacma baboons, Papio ursinus, suggests that the strength and stability of female-female relationships has a stronger impact on their reproductive success and longevity than does their dominance rank. (Silk et al 2003, 2009, 2010). This suggests that females may use social tactics to offset the effects low rank. This project extends this work to provide comparable data on the third species of olive baboons, Papio anubis.

Partners: Uaso Ngiro Baboon Project

  Research Team


This research project is currently open to funding opportunities. For more information, please reach out to the project contact listed above.


Städele, V., Roberts, E.R., Barret, B.J., Strum, S.C., Vigilant, L., Silk, J.B. 2019. Male-female relationships in olive baboons (Papio anubis): Parenting or mating effort? Journal of Human Evolution 127: 81-92.
Silk, J.B., Roberts, E.R., Städele, V., Strum, S.C. 2018. To grunt or not to grunt: factors governing call production in female olive baboons, Papio anubis. PLoS ONE 13(11): e0204601.
Silk, J.B., Roberts, E.R., Barrett, B.J., Patterson, S.K., Strum, S.C. 2017. Female–male relationships influence the form of female–female relationships in olive baboons, Papio anubis. Animal Behaviour 131, 89-98.