A recent article suggests that allowing polygyny would increase violent crime to such a degree that it would stifle economic growth. This is a logical conclusion if you assume that polygyny leaves many men without wives. The modern economy, however, has already disenfranchised the majority of low-income men from the marriage market.
So are we certain that polygyny in the industrialized world would make a difference to crime rates?
The authors of this paper write:
Faced with high levels of intra-sexual competition and little chance of obtaining even one long-term mate, unmarried men will heavily discount the future and more readily engage in risky status-elevating and sex-seeking behaviours. This will result in higher rates of murder, theft, rape, social disruption, kidnapping (especially of females), sexual slavery and prostitution.
There is plenty of evidence to back up this claim. Using data that followed men with criminal records throughout their lifetime (from age 17 to age 70), one study found that men were half as likely to commit a violent crime in periods of their life in which they were married compared to periods in which they were single.
A second study, using inmate data from Nebraska, found a similar result and provided additional evidence that marriage reduces binge drinking and drug use – two behaviors which themselves contribute to criminality.
My question, though, is not whether single men are more likely to be criminals, but rather whether legalized polygyny would actually reduce the propensity of low-status men to marry in industrialized countries.
The authors of this paper provide a back of envelope example illustrating that a system in which 5% of men have four wives, 10% have three wives, and 25% have two wives, leaving 40% of men unmarried.
That may seem like a veritable army of angry sexless men all poised to commit unthinkable criminal acts. However, in the U.S. today only 48% of men with a high school education are married compared to 72% of the same men back in 1960 and 64% of college educated men today.
The economic realities of modern life – such as the ability of women to support themselves and the low earning ability of unskilled male workers – has already done what polygyny could only do if it was adopted at completely unrealistic levels. Many, many low-income men already have very little chance of finding a long-term mate leaving many, many women available to marry hypothetical polygynists.
This does leave us with one unanswered question: If single men are more likely to engage in criminal activity, why is it that while the bachelorhood rates of low-income men have been increasing over the past several decades crime rates have been steadily decreasing?
Perhaps the answer is that the high rate of incarceration is reducing both crime and marriage rates. We have talked about this before (see The War on Drugs is Reducing Marriage Rates), but as far as I know incarceration explains only a part of the decline in marriage and almost none of the decline in crime.
Henrich, Joseph, Robert Boyd, and Peter J. Richerson (March 2012). “The puzzle of monogamous marriage.” Philosophical Transactions of the Royal Society B. doi:10.1098/rstb.2011.0290 1471-2970