Does all this de facto polygamy bursting through the seams of our nominally monogamous culture tell us anything about our evolved psychology? To answer that, we should examine the types of small-scale societies in which nearly all of our evolution has occurred. When we do so, we find that these hunter gatherer and tribal societies have, throughout the world, historically practiced polygamy. Although most men in these societies strive for polygamy, however, only a minority can achieve it, because maintaining a large family requires an often prohibitively high degree of wealth and status. Further, because it is generally difficult to store and hoard wealth in small-scale societies, even men who do achieve polygamy can usually afford no more than two or three wives. It wasn't until the emergence of large-scale agricultural civilization, a few thousand years ago, that wealth- became possible and powerful men began accumulating large harems of hundreds or thousands of women. This pattern occurred in similar ways all over the world, as Laura Betzig describes in Despotism and Differential Reproduction. So once the ecological constraints on polygamy were lifted, high status men began accumulating many more wives than they had in small-scale societies.

Another contrast between polygyny and polyandry is pointed out by Miriam Zeitzen in her book Polygamy: whereas men compete intensely to attract multiple wives, and male status is positively correlated with number of wives, women don't compete to acquire multiple husbands, and female status is not related to number of husbands. Polyandrous marriages in fact tend to be initiated by the co-husbands, who are nearly always brothers, for economic and reproductive reasons (e. . to avoid partitioning scarce arable land, or because the brothers can't find wives individually). Zeitzen also notes that these marriages involve a relatively large workload for the wife, in terms of the services--both domestic and sexual--that she is expected to provide for her husbands. (Many Western men, who might imagine that providing sexual services for multiple spouses would be a nice responsibility, will be surprised to learn that polyandrously-married women tend to find it onerous).

So the more challenging question is: Why, given the "naturalness" (I hesitate to use that term, because in an important sense everything is natural, but hopefully you'll get my meaning) of polygyny, did the West end up proscribing polygyny and prescribing monogamy? I'll answer this question in my next post.

Copyright Michael E. Price 2011. All rights reserved.