Most animals face daily decisions, such as where to forage or nest, which can be critical for their fitness. In group-living organisms, the decision-making process is complicated by a potential conflict of interests among group members, which nonetheless must collectively reach some form of agreement if the group is to remain together. In collective decisions, it is typically assumed that consensus arises through mechanisms of information sharing and positive feedback.
Models of collective behaviour have often drawn from particle physics and typically assume that group members are identical entities, focussing on the influence of interactions. However, a growing body of evidence indicates that animals are far from this ideal, and that groups often exhibit consistent inter-individual differences in behaviour (behavioural syndromes or animal personality). Furthermore, the available data indicate that the distribution of personality types in a group can influence the outcome of various collective actions. One context in which collective decision-making is crucial is group movements. These actions are essential for groups to maintain cohesion while also tracking resources or evading threats. Collective movement decisions are thought to arise through a mechanisms of positive feedback and may be coupled with a quorum response.
In this seminar, I will introduce the theoretical approach we used to examine whether personality differences could explain the spontaneous collective decision dynamics in a group of Capuchin monkeys. Specifically, we tested the hypothesis that within-group variation in personality alone is sufficient for collective decisions to arise. Spoiler alert: it is!