August 13, 2005

Problems with "The Problem with Polygamy"?

A reader responds to my 2002 article on the basic problem with polygamy: if a man has more than one wife, another man has none.

You write that if 50% of Kenyan men have a polygamous marriage, then at least 100% of the women must be in one too, and the remaining 50% men would have to remain bachelors. This would obviously be true if (1) the sexes are equal in numbers, and (2) the population remains constant.

However, to (1), poor countries have high infant mortality which typically affects boys more than girls, and Africa has plenty of civil wars and other violent features which mostly weed out young men. In Africa so far, this is not counterbalanced by mass access to the gender-selective abortion which is weeding out girls in Asia. So, it is very likely that when measured at age 10, age 20 or age 30, the percentage of females will be higher than the percentage of males, and increasing.

To (2), men typically marry younger women, with the age difference increasing in proportion to the age at the time of the wedding. This effect is fairly restricted in the West but very stark in Africa and the Muslim world. As the Persian maxim says, a man must marry a woman who is half his age plus 7 years, i.e. a bride of 22 for a groom of 30, a bride of 30 for a groom of 46. And as the Chinese proverb says, "a man is as young as the woman whose bed he shares". Now, in fast-growing populations, doubling in less than 20 years, as is the case in most places from Pakistan to Senegal, every two 32-year-old men can share three 20-year-old brides between them. And this even if the sex ratio is 1:1. This means that if the creamy layer of the 20% wealthiest or otherwise most attractive men have two or three or four wives, they can still leave one for all the less fortunate men.

Of course, in countries where birth control has caught on along with sex-selective abortion, the picture is the reverse: fewer women in the lower age ranks, and within every age group fewer females than males. I presume that a sociobiologist like yourself can imagine what the consequences will be in another generation: Chinese men fighting amongst themselves or emigrating to scout for Russian women, etc.

I wasn't able to confirm that African countries have low male to female sex ratios. The figures in the CIA World Factbook look pretty similar to Western countries: for example, in Kenya the male population in ages 15 to 64 appears to be about 1% larger than the female population. I also looked at Botswana, Eritrea, and Ghana, three other African countries with functioning governments (as opposed to, say, the Congo or Zimbabwe) and thus some hope that Census figures might be accurate. I found male to female sex ratios similar to the west, with just a few percent more women than men in the 15-64 range.

But who knows how accurate the data are for Africa, especially in violence prone countries? But, then, is the correlation between polygamy and violence accidental, or does having a lot of surplus young men generate violence?

On the other hand, perhaps the slave trade took more men than women, making the male to female ratio lower in previous centuries?

You're right that population growth would mitigate some of the effects of polygamy, especially in gerontocratic polygamous systems, although rapid population growth has mostly been confined to the the last few generations, with only slow growth in Africa before the 20th century. Africa was not densely populated until the last couple of decades because the enormous disease burden prevented urbanization.

Of course, it could be that social norms often become inscribed during a successful expansion, such as the Zulu in the 19th Century, when polygamy's cost to young men is less due to greater growth and more conquest and bride-stealing. Then the customs of the good old days when the tribe flourished become the tradition even when dysfunctional in a more stable world. (I suspect that might be a general pattern: that traditions and expectations tend to get established during a peak period of growth, such as Israel under David and Solomon, and France under Louis XIV and carry on even when the group no longer is winning.)

My published articles are archived at -- Steve Sailer

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