FAMILY/ The Perils of Polygamy
In the course of history, approximately 85 percent of societies have practiced polygamy. Pushed by advocates of same-sex marriage and multiculturalism, some scholars, such as the signers of “Beyond Gay Marriage,” argue that it is irrational and bigoted for contemporary society to limit marriage to just two people. However, there is no bigotry in treating different things differently, and there are many important differences between polygamy and monogamy in practice as well as in principle.
There are three main forms of polygamous relationships: polygyny, polyandry, and polygynandry. In polygyny, by far the most common form of polygamy, one man may marry a number of wives. In polyandry, one wife has two or more husbands. This form of polygamy is extremely unusual, and often takes the form of two brothers marrying the same woman. In polygynandry, two or more wives marry to two or more husbands. Polygynandry is even more rare than polyandry, but will be similar in some respects to polygyny, insofar as a man has more than one wife. Since both polygynandry and polyandry are virtually non-existent, I’ll focus on the more common case of one man with multiple wives, and use the more common term polygamy to describe this arrangement.
Now let us turn to the practical considerations drawn from human experience. Recent empirical research suggests that, in virtually every respect, polygamy is socially detrimental—to society in general, to men, to women, and to children. These problems arise because of the nature of human reproduction.
In human reproduction, slightly more male than female babies are born (approximately 105 boys to 100 girls). As boys are more likely to die of natural causes as infants and from violence before they marry and reproduce, ceteris paribus, at any given marriageable age, there will be approximately 50% males and 50% females. Given roughly equal numbers of males and females as found in nature, polygamy and monogamy shape society in radically different ways. In a monogamous society, for each man there is a corresponding woman. William Tucker notes that this gives “every man [and every woman] a reasonable chance to mate.” By contrast, in a polygamous society, some men take multiple wives, but this leaves other men with greatly diminished prospects of marriage or an exclusion from mating altogether. The question under consideration, then, is what social effects does this arrangement bring?
In their 2012 article, “The Puzzle of Monogamous Marriage” appearing in Philosophical Transactions of the Royal Society, Joseph Henrich, Robert Boyd, and Peter J. Richerson used converging lines of evidence from the social sciences to compare polygamous and monogamous societies. They found that polygamous societies differ from monogamous societies in terms of violent crimes, female educational attainment, domestic violence, parental investment in children, and economic productivity.
A wealth of sociological information points to the fact that single men commit the vast majority of violent crimes. Women and married men seldom murder, rob, rape, and assault in comparison to single men. So, since there are many more single men in polygamous societies, polygamous societies have higher rates of violent crime.