Essays on Cooperation: Scales of Interactions, Competition, Punishment

Cooperation is evolutionarily puzzling, as it benefits others but it is individually costly. In order to explain how it can emerge and be maintained over time, therefore, a mechanism is needed for cooperation to be under positive selection. In this dissertation, tree behavioural experiments try to deepen our understanding of three well known mechanisms previously established in the literature: indirect reciprocity, between-group competition and peer-punishment. Chapter 1 expands our understanding of reputation-based indirect reciprocity as a mechanism to sustain cooperation in large groups. It explores under which conditions allowing for multiple scales of (group) interactions undermines or enables group cooperation at the larger scale via reputation-based rewards. Chapter 2 focuses on the cognitive underpinnings of cooperative behaviour. By adopting a dual-system perspective on the decision-making process and starting from the recent literature on the Social Heuristic Hypothesis, it investigates how cooperation triggered via between-group competition spills over to contexts where cooperation is not incentivized and, crucially, across group boundaries. Chapter 3 investigates the extent that prosocial third-party punishment is carried out to signal trustworthiness to potential future social partners. In particular, mirroring previous studies on the emergence of competitive altruism under partner choice, it disentangles the effect of mere observability with the effect of partner choice on the rates of punishing decisions.