Wild chimpanzee groups increase social connectivity prior to risky collective action
Year: 2026
Type: preprint
Abstract: Cooperation is foundational to complex sociality, yet presents profound evolutionary dilemmas – costs and benefits are rarely distributed evenly and the decision to collaborate or defect can involve a complex contextual calculus. These challenges are compounded when cooperation scales from pairs to groups. Group-level cooperation is fundamental to many species’ success, but how is it sustained and regulated in nature? One route to addressing this question is to examine how individuals reorganise affiliative interactions in anticipation of group-level cooperation. We examine such pre–cooperative reorganisation using long-term data (2013-2018) from three neighbouring groups of wild chimpanzees at Taï National Park, Côte d’Ivoire. We found that prior to risky proactive territorial defence, chimpanzees formed more broadly connected, yet more diffuse, affiliative networks. Specifically, chimpanzees groomed and played with more group members on days of proactive territorial defence, and this pattern was temporally-sensitive, with increased affiliation occurring before, not after, the cooperative act. Chimpanzees accessed a broader range of partners through increased interaction efficiency by switching between more partners with shorter interactions per partner. This pattern suggests a shared basis of dynamic social readjustment in advance of group-level social dilemmas in hominids, potentially providing foundations for formalized systems of affiliation in human societies.
Institutions: Centre National de la Recherche Scientifique, German Primate Center, Max Planck Institute for Evolutionary Anthropology, Swiss Centre for Scientific Research, Chimpanzee and Monkey Protection for Intact Cultures, University of Göttingen, Lyon 1 Université, Institut des Sciences Cognitives Marc Jeannerod, Institut des Sciences Cognitives, Harvard University, German Centre for Integrative Biodiversity Research
Language: English
Topic: Primate Behavior and Ecology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7164879256