The evolution of cooperative sociality: Conflict and coordination in ravens and chimpanzees

Abstract

Human cooperation is considered to be qualitatively different from that of other animals, both in scale and in complexity.  Humans engage in large-scale, intricate joint endeavours to achieve feats one alone could not and cooperate even with those they may never meet again. The reasons behind this unique cooperative sociality remain unclear, and the extent to which other social animals are able to purposefully enact and maintain joint actions is up for debate, despite apparent cooperative behaviours being widespread in nature. One way in which human cooperative societies are thought to be maintained, and the benefits of cooperative living kept higher than that of defection, is through our ability to enforce cooperative norms and mitigate conflicts. Conflict management has been studied extensively in other social animals, and the use of reconciliatory post-conflict affiliation as a strategy to reduce the costs of conflict is considered to be a key way in which animal groups are kept stable. Systematic functional analyses of post-conflict affiliation and its direct relation to social cohesion are lacking, however. The first study presented in this thesis explicitly tries to untangle the potential social and non-social determinates of post-conflict behaviour in ravens, by comparing post-conflict periods to those matched on arousal. Affiliation was found to occur at similar rates after other stressful events as after conflicts, indicating a potentially more general tension-reducing role of assumed reconciliation. Conflict management in social animals could potentially be less strategic than previously considered. Another seemingly exceptional facet of human cooperation is our ability to enact cooperation in large and complex groups. Although large-scale cooperation, such as group hunting and territory defence, is reported in wild animals, much of the experimental work into animal cooperation has been conducted on dyads. Studies two and three of this thesis, in presenting ravens and chimpanzees with cooperation problems that need a variable number of cooperators for success, add to the small but growing number of n-player cooperation tasks. These studies aimed to test the functional and cognitive limits of coordinated action in these species, as well as to examine the impact of player number on cooperative success. In concordance with dyadic studies, in both species cooperative success could be achieved without evidence for purposeful coordination and causal understanding of the need for a partner. Extending cooperative paradigms beyond the dyad also stretched the limits of their abilities, with triadic cooperation either difficult or impossible to achieve.

Date of Award	6 Jan 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Frank Podd (Supervisor), Tobias Galla (Supervisor), Susanne Shultz (Supervisor) & Keith Jensen (Supervisor)