Cooperation during cultural group formation promotes trust towards members of out-groups.

People often cooperate with members of their own group, and discriminate against members of other groups. Previous research establishes that cultural groups can form endogenously, and that these groups demonstrate in-group favouritism. Given the presence of cultural groups, the previous literature argues that cultural evolution selects for groups that exhibit parochial altruism.

The causal effect of market priming on trust: an experimental investigation using randomized control.

We report data from laboratory experiments where participants were primed using phrases related to markets and trade. Participants then participated in trust games with anonymous strangers. The decisions of primed participants are compared to those of a control group.

Competition for trophies triggers male generosity.

Background: Cooperation is indispensable in human societies, and much progress has been made towards understanding human pro-social decisions. Formal incentives, such as punishment, are suggested as potential effective approaches despite the fact that punishment can crowd out intrinsic motives for cooperation and detrimentally impact efficiency. At the same time, evolutionary biologists have long recognized that cooperation, especially food sharing, is typically efficiently organized in groups living on wild foods, even absent formal economic incentives.