Group cooperation, carrying-capacity stress, and intergroup conflict

Peaceful intergroup relations deteriorate when individuals engage in parochialcooperation and parochial competition. To understand when and why intergrouprelations change from peaceful to violent, we present a theoretical frameworkmapping out the different interdependence structures between groups. Accordingto this framework, cooperation can lead to group expansion and ultimatelyto carrying-capacity stress. In such cases of endogenously created carryingcapacitystress, intergroup relations are more likely to become negativelyinterdependent, and parochial competition can emerge as a response. We discussthe cognitive, neural, and hormonal building blocks of parochial cooperation,and conclude that conflict between groups can be the inadvertent consequenceof human preparedness – biological and cultural – to solve cooperation problemswithin groups.Social decision makin