The prevalent models of the transmission of intergroup aggression are of the dominant individuals who coerce others into aggressive behaviors and of dominant leaders being necessary for moments of crises. However, such models leave out other ways open for cultural species. We investigate how aggression towards enemy out-group spreads among in-groups during intergroup conflicts. Focusing on the role of learning biases, we tested whether the prestige and credibility-enhancing displays (CREDs) of in-group leaders motivate other in-groups to participate in intergroup aggression. Our results show that the transmission of intergroup aggression is promoted by the prestige and CREDs of group leaders, not their dominance. We conclude that given the context of an intergroup conflict, leaders can increase participation in aggressive behaviors towards out-groups by prestigious motivation, sidestepping the coercive pathway of dominance and opening the door for voluntary participation in intergroup aggression. The aim of the project is to incorporate valuable feedback we received from the editorial board of Evolution and Human Behavior, improve our manuscript and publish it as an open-access research article in Plos One.

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