Says a study by two professors in Belgium:
Intriguingly, across the world the main social groups which practice polygyny do not consume alcohol. We investigate whether there is a correlation between alcohol consumption and polygynous/monogamous arrangements, both over time and across cultures. Historically, we find a correlation between the shift from polygyny to monogamy and the growth of alcohol consumption. Cross-culturally we also find that monogamous societies consume more alcohol than polygynous societies in the preindustrial world. We provide a series of possible explanations to explain the positive correlation between monogamy and alcohol consumption over time and across societies.
(via The Dish via Tyler Cowen)