The Limits Of Naive Eugenics

A Cluster Of Specific Practices Associated With Islam

When Westerners think about the Islamic world, a number of distinctive cultural practices come immediately to mind:

* Polygamy

* Limitations on the interactions of women with men who aren't family members

* A high frequency of cousin marriage

* Heavy use of corporal and capital punishment

For what it is worth, all of these cultural practices have deep pre-Islamic roots, and are not universal among peoples and societies where Islam is practiced. Islam can be seen more as a moderate reform of these practices in societies that had them (for instance, imposing limits on polygamy and some procedural limitations on arbitrary clan justice) and as a vector for their wider transmission of these practices to societies that did not (often with more limited impact), rather than the ultimate source of these practices.

All of these can be seen as motivated naively by eugenic considerations.

Eugenic Motivations For Polygamy

Polygamy tilts sexual selection in favor of men who have been unusually successful in their society, and pushes men who were unusually unsuccessful in their society out of the gene pool. Animal breeding using this approach heavily with great success to maximize desired traits. Like polygamists everywhere, wife's of polygamous men also tend to have many children per women which is also well established in animal breeding as a successful technique.

Eugenic Motivations For Isolating Women From Non-Family Men

Limitations on the interactions of women with men who aren't family members is a way to prevent infidelity from diluting polygamy and assortive marriage, which men who are excluded from having wives, and polygamous wives who receive less attention from their husbands, may have a more intense inclination to try to engage in than in a more Western style marriage system.

Eugenic Motivations For Cousin Marriage, Their Flaws, And Why The People Who Devised It Didn't Realize This Point

Cousin marriage is one form of assortive marriage that is intended to keep what are believed to be more fit in group genes from being commingled with less fit out group genes that has been widely practice in every place with a hereditary monarchy and aristocracy at those elite levels. Awareness of the risks of inbreeding depression and of the social risks of nepotism and clannishness that this system gives rise to were not really well understood until the 20th century and old habits die hard.

Why didn't experience from animal breeding lead to an awareness of this risk?

Part of the issue is that inbreeding depression doesn't badly affect all children of inbreeding parents. Mostly, inbreeding greatly increases the likelihood that undesirable recessive traits which everyone has in their genome will become dominant in the children. But, lots of children of parents who are cousins are just fine, especially if they are not "double cousins", a concern that no marriage system I am aware of had the foresight to treat differently than ordinary first cousins, but arises naturally in a society with lots of cousin marriage.

Also, while cousin marriage, where it has been practiced, has mostly been perceived as assortive, when the underlying basis upon which assortive marriage is taking place is not itself merit based as opposed to hereditary or even economic, it impedes the capacity of the in group that one seeks to enhance to be enriched with fit people from outside the in group. And, the longer this endures, the more rot degrades the quality of the in group and exclusion improves the quality of the out groups who are not losing their best children to the in group.

In pre-modern agricultural animal breeding, only the males with the traits that breeders deem most desirable breed at all, and females with undesirable traits are also ruthlessly put down rather than bred, without much concern for inbreeding issues per se. So, animal breeders, who are the experts on sexual selection in pre-modern agricultural societies, don't encounter much inbreeding depression.

But, in human societies, where even the most polygamous society has a profoundly higher proportion of breeding males and only the most severe recessive traits or inbreeding depression effects are sufficient to keep someone out of the gene pool, inbreeding is a much more serious issue.

Eugenic Motivations For Capital Punishment

Corporal and capital punishments used heavily (as most pre-modern societies did before they could afford prolonged imprisonment of serious criminals) should keep any genetic tendencies that predispose people to criminal conduct out of the gene pool.

Islamic Societies Are Not A Eugenic Success Story.

Now, in practice, Islamic societies in which all four of these practices are present are not what a naive eugenically minded individual would expect or would have sought from many dozens of generations of applying these polices.

Men in these societies are not measurably less predisposed to engage in criminal activities. The members of these societies are not academic standouts relative to societies that do not adhere to these practices, nor are they standouts with respect to other traits with a significant hereditary component, like conscientiousness or extraversion that are associated with socio-economic success.

How Can We Determine Specific Reasons Why?

The thought experiment and tricky empirical question is to try to tease out what effects these practices have had independently, because inbreeding depression effects may have been so strong that they mask beneficial implications of the other practices that are actually mitigating the downsides of cousin marriage.

For example, both England and the Islamic world have a history of heavy capital punishment use. Is there any evidence that this had a positive long run effect? In part, this is a function of the extent to which genetic predisposition to serious crime is a strong cause of crime. If it is, one would naively expect widespread capital punishment use, if not too inaccurate, to have a positive eugenic effect. But, if non-hereditary factors predominant, capital punishment shouldn't have much of an impact.

In the test case of Mormons, who briefly had high rates of polygamy, but little inbreeding, the social historical and economic historical literature suggests that children of polygamous families had poor outcomes relative to the smaller families of monogamous families, because fewer resources (both in terms of economic resources and less tangible resources like paternal attention) were available per child in polygamous families, and these deficits may have outweighed any eugenic advantage that polygamy could have conferred.

The Case For Humility In Policy Making

This post doesn't seek to provide final answers to the questions these thought experiments ask. Instead, it merely serves as a cautionary reminder that a eugenic proposal, even one that is well meant and seems sound with available knowledge that has solid empirical and theoretical foundations, can fail badly if the analysis overlooks something important in even on of many components of the plan. Hence, policy makers in this arena should show humility.