a1 London School of Economics and Political Science
I propose an evolutionary psychological perspective on wars and suggest that the ultimate cause of intergroup conflict may be the relative availability of reproductive women. Polygyny, which allows some men to monopolize all reproductive opportunities and exclude others, may increase the prevalence of civil wars, but not interstate wars, which did not exist in the ancestral environment. The analysis of the Correlates of War data support both hypotheses; polygyny increases civil wars but not interstate wars. Polygyny explains a greater proportion of the variance in civil war experience than democracy does in interstate war experience. If the democratic peace is the first law of international relations (interstate wars), then polygyny may be the first law of intergroup conflict (civil wars).
(Received September 19 2006)
(Accepted April 12 2008)
Satoshi Kanazawa is a reader in management, London School of Economics and Political Science, London WC2A 2AE, UK.