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December 15, 2010

Incest vs. polygamy

Filed under: Culture,Evolutionary Psychology,Social Biology — Razib Khan @ 1:31 am

Today in Slate there’s an argument for why society should discourage first-degree incest. The main thrust of the piece seems to be broadly utilitarian, in that incest is destructive to the family unit and society has a rational motive in discouraging the practice. The reason that the argument is even made is because of analogies that some social conservatives make between incest and gay marriage. I’m not too interested in the argument against first-degree incest, because I think this is a practice which is aberrant because there are biological dispositions most humans have which make it unthinkable.* Though the genetic reasons are broadly well known, Steven Pinker reports on the psychological mechanisms which enforce the taboos in The Blank Slate.

Of course there are exceptions to the rule. The first-degree incest taboos can be violated in the case of royal families which wish to preserve and accentuate their divine genealogical essence. This was famously well known in ancient Egypt down to the Roman conquest, but one also found the practice in Hawaii. In rural Egypt apparently brother-sister marriage continued among commoners (who presumably emulated the elites) down to the Roman period. Human nature has dispositions in many cases which are not “hard-wired.” But the disposition in this case is so strong that I believe arguing about the legality of consensual adult incest is an academic matter. The discussion is only surfacing because of its possible relevance to another issue, gay marriage.

Polygamy though is a different case. Here the ethnography seems to be clear that though the majority of men in the majority of societies did not practice polygamy, in most cultures polygamy was acceptable, and commonly practiced by high status males. In many cases polygamy was the preferred ideal, which was not attainable for the typical male due to economic constraints. Only with the spread of Western-normative mongamous customs, inherited from the Greeks and Romans, has polygamy been marginalized.

But we may be better for it. Polygamy’s many wives don’t capture ‘market value’:

Economist Shoshana Grossbard admits she was naive when she did her doctoral thesis on polygamy more than 30 years ago at the University of Chicago.

Then, she believed that a simple supply-and-demand analysis would explain the economics of polygamous societies.

Besides, she says, “I thought it was cool to say that polygamy might be advantageous to women and repeat what Gary Becker (her thesis adviser and Nobel laureate) has said.”

Polygamous societies have a higher frequency of arranged marriages. It’s not surprising, says Grossbard. Young women aren’t likely to choose old men for husbands, plus men find young wives easier to control.

Of course, that increases the likelihood of early widowhood and financial hardship.

In societies where a bride price is paid, women don’t “capture their increased market value.” Instead, she says, potential husbands pay the fathers. No money goes to the bride.

Divorce tends to be easier in polygamous societies. The threat of it keeps women in line and it allows men to shed wives who are too old or noncompliant.

Child custody almost always is the right of the father.

Isolating women makes it more difficult for them to escape and makes them even more financially dependent on their husbands.

As beautiful as the harem in Grenada’s Alhambra is, Grossbard says, “The whole institution is typical of polygamous societies.”

There, eunuchs – castrated men – guard the wives.

There are variations in the nature of polygamy. My understanding is that in some African societies women in polygamous relationships have their own independent economic life, and the male is a transient between matrifocal households. The opposite extreme occurs in Muslim societies where women are secluded from men and denied from participation in public life.

In any case, unlike first-degree incest or gay marriage, polygamy does remain rather common, and legal, in much of the world:


One must note that in some nations, such as India, polygamy is only legal for minorities for which it is a traditional custom. That being said, in many nations where it is legal, it is not always common, nor is it socially acceptable in many circles.

But it is notable to me that gay marriage & incest, and polygamy, are very different cases. Polygamy is a practice which has broad appeal, and even in many societies where it is banned de facto polygamy is not uncommon. The integration of a ban on polygamy into the legal codes of societies such as India and China is interesting, because the practice was not unknown among pre-modern elites, and persisted down to the 20th century. The film Raise the Red Lantern is about a polygamous household in 1920s China. The historical roots of the turn against polygamy seems to be tied to the rise of Western hegemony within the last few hundred years, and that itself derives from the integration of Greco-Roman norms into the Christian religion. The Romans and Greeks were obligate monogamous peoples in the Classical period, and this obligate monogamy became a feature of Christianity (though not Judaism, which retained polygamy among Ashkenazim until the 10th century, and other Jewish groups which may still retain the practice, though no longer in Israel). The barbarian warlords of Northern Europe often had to make their accommodation with this “Roman” custom upon their conversion to Christianity (though the reality is that the Church often gave monarchs de facto exemption).

If the dominance of the ideal of monogamy is a contingent accident of history, will we see a shift toward greater pluralism in the near future, with the decline of the West? This is not an implausible contention. But, I also do wonder if legally sanctioned polygamy does not trigger a destabilizing “winner take all” dynamic in complex societies, producing a lack of social trust which means that such societies have limits in terms of the scale of their complexity. In other words, perhaps advanced economies necessarily need and foster a level of gender equality which formal polygamy is simply not consonant with?

Addendum: The existence of “super-male” lineages such as that of Genghis Khan is a testament to the power and presence of polygamy as a genetic phenomenon over the last 10,000 years. Even if most men in a given society can not practice polygamy because of economic and social constraints, it may be that the majority of future generations are descended from polygamists because of their fecundity, and that of their polygamous male offspring who would inherit their status.

* No comments about how you fantasized about your sister to refute my generalization!

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