Between-group competition and human cooperation

Abstract

A distinctive feature of human behaviour is the widespread occurrence of cooperation among unrelated individuals. Explaining the maintenance of costly within-group cooperation is a challenge because the incentive to free ride on the efforts of other group members is expected to lead to decay of cooperation. However, the costs of cooperation can be diminished or overcome when there is competition at a higher level of organizational hierarchy. Here we show that competition between groups resolves the paradigmatic 'public goods' social dilemma and increases within-group cooperation and overall productivity. Further, group competition intensifies the moral emotions of anger and guilt associated with violations of the cooperative norm. The results suggest an important role for group conflict in the evolution of human cooperation and moral emotions.

Figure 1

Investments to the group project. Triangles, PG treatment; circles, GC treatment. Symbols denote the mean of session means. Error bars denote 95% confidence interval of mean.

Figure 2

Box-plot figure of perceptions of own-group members on a scale from collaborator to competitor in the PG treatment and in the GC treatment.

Figure 3

Box-plot figure of feelings of anger towards own-group members who donated less to the group project, and feelings of guilt when a subject earned more than own-group members. PG: public goods treatment; GC: public goods with group competition treatment.