Dominance and affiliation mediate despotism in a social primate

Group-living animals routinely have to reach a consensus
decision and choose between mutually exclusive actions
in order to coordinate their activities and benefit from sociality
[1, 2]. Theoretical models predict ‘‘democratic’’ rather
than ‘‘despotic’’ decisions to be widespread in social vertebrates,
because they result in lower ‘‘consensus costs’’—
the costs of an individual foregoing its optimal action to
comply with the decision—for the group as a whole [1, 3].
Yet, quantification of consensus costs is entirely lacking,
and empirical observations provide strong support for the
occurrence of both democratic and despotic decisions in
nature [1, 4, 5]. We conducted a foraging experiment on a
wild social primate (chacma baboons, Papio ursinus) in
order to gain new insights into despotic group decision making.
The results show that group foraging decisions were
consistently led by the individual who acquired the greatest
benefits from those decisions, namely the dominant male.
Subordinate group members followed the leader despite
considerable consensus costs. Follower behavior was mediated
by social ties to the leader, and where these ties were
weaker, group fission was more likely to occur. Our findings
highlight the importance of leader incentives and social
relationships in group decision-making processes and the
emergence of despotism.