We argue that polygyny creates a social imbalance where few, economically well-off men marry many wives and many poor men marry late or never. By definition, polygyny produces what we refer to as “excess men.” In order to gain material wealth, excess men are likely to raid, plunder, and rob neighboring ethnic groups. We test this hypothesis with georeferenced data on polygyny and intergroup conflict in rural Africa and find strong support. Drawing on Afrobarometer survey data, we explore the underlying mechanisms and find that young men who belong to polygynous groups feel that they are treated more unequally, are more frustrated and are readier to use violence in comparison to those belonging to monogamous groups. Our article makes an important contribution to the peace, conflict, and development literature by emphasizing a fundamental aspect of human life: marriage and family.

Carlo Koos

Senior Researcher

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