Selective mimetism at departure in collective movements of Macaca tonkeana: an experimental and theoretical approach

In primates, authors have reported the specific organization of individuals during collective movements. Some authors have suggested that intentional mechanisms underlie this particular organization because primates have high cognitive abilities that can allow them to use this kind of behaviour. However, mechanisms underlying the emergence of complex systems are not necessarily complex and can be based on local rules. We investigated the joining processes observed during collective movements in one semifree-ranging group of Tonkean macaques, using an individualized agent-based model. The complex patterns observed, such as departure latencies, associations and order of individuals at departure of a collective movement, could be explained using a rule based on affiliative relationships. The decision an individual took to join the movement depended on the departure of its strongly affiliated individuals. Thus even in primates, complex collective behaviour may emerge from interactions between individuals following local behavioural rules.