Monogamy and society-level selection?

Joe Henrich, a former professor at Emory and now magister acronym at UBC, is wielding his anthropological expertise against polygamy. In a BC court case against a fundamentalist Mormon commune, Joe was asked to file his anthropological opinion, all things considered, on whether polygamy is good or bad for society. Bad takes the cake.

The thrust (hey-o!) of the cake-taking argument is that monogamy means mates and social equality for everyone (though mostly the menfolks), reducing the social burden of crime, aggression, poor economic habits, etc. disproportionately created by unhappy, mateless young men. Read a Guardian distillation here, the full brief there. If you want to skip past the CV, etc. to the article, it starts on page 24.

Evidence is strong that an abundance of young men unable to get married (or simply unmarried men) is correlated strongly with increases in crime: take, e.g., the 90% increase in crime in China between 1988 and 2004. However, the hypothesis that polygyny results in poorer economic growth (and hence lower GDP) is based on the work of only one author, the delightfully-named M. Tertilt, whose economic models predict savings and investment when men don't have to compete fiercely for partners. (As an aside, mate competition is presumably is less-intense in monogamous societies? rrr.... I'd be interested in a life-history approach in the contemporary U.S. on the saving habits of unmarried young folks, period).

The argument that polygyny drives down marriage-age for girls has its points (did you know that brides as young as 12 and 13 were common in the Wild Wild West?), but, from my cursory reading, doesn't address potential structural confounds - e.g., the spread of education for women leading to older age at marriage potentially coming hand-in-hand with Western rule/laws/ideals about monogamy.

The proposed relationships with women's social equality and democracy don't hold water for me. It's nice in theory, but according to this same paper, the West has had government-mandated monogamy for over a thousand years! Women only got the vote in the last tenth of that time. Hell, Columbia University didn't let women attend until 1981! And although a Brit in 1215 may have gotten a warm and fuzzy feeling that the king couldn't have more wives than he, I hardly imagine it inspired the Magna Carta. (Insert witty marriage-as-habeus-corpus joke here.)

On a side note in the political part of the brief, given that that Sparta, Athens, Rome, and early Christian Europe imposed monogamy on citizens, I'm also loath to accept single-citation statements like, "polygynous societies engage in more warfare."

The leaders of past societies have often harnessed pools of "surplus men" by sending them out to conquer new lands, or peoples.

Low-status males (and females!) being sent into danger abroad to do the empire's dirty work? Sounds vaguely familiar.... though perhaps current sentiment against gay marriage disqualifies the U.S. from representing a truly monogamous society.

All in all, though, an interesting, well-organized, well-written distraction from my NSFDRG. Thanks, Joe.