Science says monogamy is good for society


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Well, hello again imaginary reader of this blog. I’m ready to dust this site off and finally start adding some new posts, after a long hiatus. Since the last post, I’ve written my doctoral dissertation, and will be defending it in just 2 days!

I’ve also gotten engaged, which is why I was so interested in this article: The Puzzle of Monogamous Marriage, written by researchers at the University of British Columbia.

The authors provide evidence from many studies of human societies arguing that monogamy is good for society. One of the basic tenets of this argument is that when polygyny (having many wives) is the norm in a society, rich and powerful men end up with proportionally more wives.

In a very egalitarian society, this might be okay, because there is a small enough difference between the social statuses of men that no single man (or small group of them) will end up marrying all the women. But in a society like those that exist in our most developed nations (like the U.S.), there is a huge gap between the most wealthy and, well, everyone else. If it was “okay”, from a cultural view, for men to have many wives, and women benefitted from marrying the most powerful men, then there would be no one left for all the other guys to marry.

Why is this inherently a bad thing, though?

As the authors argue (and provide pretty compelling evidence), that having too many unmarried men in a society increases rates of crime (such as murder, rape, kidnapping, theft, etc) and is even tied to higher substance abuse in men. These correlations, of course, don’t mean that being unmarried¬†causes men to be criminals. But they do present evidence from an earlier study that followed a group of men from age 17 to 70. Most went through multiple marriages, so they were able to follow the mens’ crime rates during married and unmarried times. In this study, being married reduced a man’s likelihood of committing a crime by 35% (50% for violent crimes). When they were divorced or widowed, crime rates went back up. (They do point out that this trend didn’t hold when men married criminal wives).

A real-life example of this can also be seen in present-day China. The widespread practice of sex-selective abortions (generally selecting for males) has led to an surplus of men in China over the past 2 decades. At the same time, crime has increased. Again, this is just a correlation, but it does warrant further study on the issue.

The hypothesis put forward by the authors is that when the prospects of finding a mate are low (as in a polygynous society where only rich and powerful men have wives), unmarried men have less incentive to think about the future and will therefore take more risks.

Other positive effects of monogamous marriage, according to this article: decreasing the age gap between husbands and wives, increasing the age of marriage for women, decreasing fertility (which increases the quality of each child, as the parents have more resources to devote to each child), decreasing child neglect and abuse, and increasing equality for women. They even provide evidence that enforcing monogamy in a society increases a country’s GDP, since each household has more money to spend on other goods if the number of children are decreased.

As you might have already guessed, there is a distinct difference between marriage and individual mating strategies. For example, a couple might be in a monogamous marriage, but one or both of the partners might be engaged in extramarital sex, or cheating. But the cultural stigma against this is strong, helping to reinforce the cultural norm of monogamy.

The article is definitely welcome for someone like me, about to enter into a monogamous marriage. This is especially true when so many articles about monogamy in humans tend to take the opposite stance: that monogamy is somehow unnatural. In contrast, this article (“The Puzzle of Monogamous Marriage”) argues that monogamy is in fact natural, since it arose by the very natural human process of adopting and enforcing cultural norms within a society. These norms were selected for because of their positive effect on society as a whole–it’s evolution.

Reference: 
Henrich, J., Boyd, R., & Richerson, P. (2012). The puzzle of monogamous marriage Philosophical Transactions of the Royal Society B: Biological Sciences, 367 (1589), 657-669 DOI: 10.1098/rstb.2011.0290

2 thoughts on “Science says monogamy is good for society

  1. Why compare the Western American version of monogamy to polygyny? Why not compare it to polyandry? Or why not compare it to polyamory? If you compare polygyny to monogamy, certainly it looks more “fair.” That’s like comparing slavery to working in a coal mine. Working in a coal mine is certainly better than being a slave, but it’s still not optimum employment, is it?

    • You’re right–I didn’t want to go into too much detail about the paper, but they do compare many normative monogamous societies (not just Western ones) to many types of polyfamoys societies. They also point out societies that are apparent anomalies, which don’t seem to fit the hypothesis, but these are all very small societies. It’s unclear how their marriage norms would scale up.

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