Monday, July 09, 2007

Why Beautiful People Have More Daughters. Part 3.

This is the third installment of my comments on the ten politically incorrect points about humans. The first discussed some framing issues and the second covered my reactions to the first three points. So this one will continue with the fourth point which gives women a short rest from being bashed. Don't worry, the bashing will continue right after this one.

4. Most suicide bombers are Muslim

Suicide missions are not always religiously motivated, but according to Oxford University sociologist Diego Gambetta, editor of Making Sense of Suicide Missions, when religion is involved, the attackers are always Muslim. Why? The surprising answer is that Muslim suicide bombing has nothing to do with Islam or the Quran (except for two lines). It has a lot to do with sex, or, in this case, the absence of sex.

What distinguishes Islam from other major religions is that it tolerates polygyny. By allowing some men to monopolize all women and altogether excluding many men from reproductive opportunities, polygyny creates shortages of available women. If 50 percent of men have two wives each, then the other 50 percent don't get any wives at all.

So polygyny increases competitive pressure on men, especially young men of low status. It therefore increases the likelihood that young men resort to violent means to gain access to mates. By doing so, they have little to lose and much to gain compared with men who already have wives. Across all societies, polygyny makes men violent, increasing crimes such as murder and rape, even after controlling for such obvious factors as economic development, economic inequality, population density, the level of democracy, and political factors in the region.

However, polygyny itself is not a sufficient cause of suicide bombing. Societies in sub-Saharan Africa and the Caribbean are much more polygynous than the Muslim nations in the Middle East and North Africa. And they do have very high levels of violence. Sub-Saharan Africa suffers from a long history of continuous civil wars—but not suicide bombings.

The other key ingredient is the promise of 72 virgins waiting in heaven for any martyr in Islam. The prospect of exclusive access to virgins may not be so appealing to anyone who has even one mate on earth, which strict monogamy virtually guarantees. However, the prospect is quite appealing to anyone who faces the bleak reality on earth of being a complete reproductive loser.

It is the combination of polygyny and the promise of a large harem of virgins in heaven that motivates many young Muslim men to commit suicide bombings. Consistent with this explanation, all studies of suicide bombers indicate that they are significantly younger than not only the Muslim population in general but other (nonsuicidal) members of their own extreme political organizations like Hamas and Hezbollah. And nearly all suicide bombers are single.

Here is where I need a research assistant. Are nearly all suicide bombers single? I can remember family members referred to in quite a few articles. But surely there is a more obvious reason for suicide bombers being younger and single (if they are): That way they don't leave grieving children behind. This type of a proximal explanation is almost always ignored in Evolutionary Psychology.

What about the religious significance of Islam that is mentioned here? The Tamil Tigers are not fighting on religious grounds, true, but are the Islamic suicide bombers really fighting for their religion or something that might be connected with the religion in their minds but has more to do with feelings of humiliation in general? I'm not sure.

And what role would polygyny really have here? Wouldn't it depend on how common polygyny actually is in the Muslim countries from which these bombers come? It seems to me that the expectation that a young man must support a stay-at-home wife is more likely to cause a large number of young men to remain unmarried in those countries than polygyny.

Note, by the way, how neatly all these points support conservative thinking about this world, even if they have to gather the evidence from diverse places.

The next point to be discussed:

5. Having sons reduces the likelihood of divorce

Sociologists and demographers have discovered that couples who have at least one son face significantly less risk of divorce than couples who have only daughters. Why is this?

Since a man's mate value is largely determined by his wealth, status, and power—whereas a woman's is largely determined by her youth and physical attractiveness—the father has to make sure that his son will inherit his wealth, status, and power, regardless of how much or how little of these resources he has. In contrast, there is relatively little that a father (or mother) can do to keep a daughter youthful or make her more physically attractive.

The continued presence of (and investment by) the father is therefore important for the son, but not as crucial for the daughter. The presence of sons thus deters divorce and departure of the father from the family more than the presence of daughters, and this effect tends to be stronger among wealthy families.

This argument is based on the assumption that women marry men for their wealth, status and power. but that men marry women for being young, big-breasted and blond. A dad can't help his daughter to get any bigger boobs, so he might as well bugger off. But he can give a son wealth, status and power. How does he give the son status and power, I wonder?

Sigh. It's more likely that men feel a son needs an adult role model of the same gender. Or the fathers may have read about all those studies which suggest that sons are hurt by absent fathers and so on. That "proximal" solution, once again. -- Note also that "significantly" here probably refers to "statistical significance" which is not the same thing as "much greater probability." I have no idea if studies actually prove what is argued here, by the way.

Next point:

6. Beautiful people have more daughters

It is commonly believed that whether parents conceive a boy or a girl is up to random chance. Close, but not quite; it is largely up to chance. The normal sex ratio at birth is 105 boys for every 100 girls. But the sex ratio varies slightly in different circumstances and for different families. There are factors that subtly influence the sex of an offspring.

One of the most celebrated principles in evolutionary biology, the Trivers-Willard hypothesis, states that wealthy parents of high status have more sons, while poor parents of low status have more daughters. This is because children generally inherit the wealth and social status of their parents. Throughout history, sons from wealthy families who would themselves become wealthy could expect to have a large number of wives, mistresses and concubines, and produce dozens or hundreds of children, whereas their equally wealthy sisters can have only so many children. So natural selection designs parents to have biased sex ratio at birth depending upon their economic circumstances—more boys if they are wealthy, more girls if they are poor. (The biological mechanism by which this occurs is not yet understood.)

This hypothesis has been documented around the globe. American presidents, vice presidents, and cabinet secretaries have more sons than daughters. Poor Mukogodo herders in East Africa have more daughters than sons. Church parish records from the 17th and 18th centuries show that wealthy landowners in Leezen, Germany, had more sons than daughters, while farm laborers and tradesmen without property had more daughters than sons. In a survey of respondents from 46 nations, wealthy individuals are more likely to indicate a preference for sons if they could only have one child, whereas less wealthy individuals are more likely to indicate a preference for daughters.

The generalized Trivers-Willard hypothesis goes beyond a family's wealth and status: If parents have any traits that they can pass on to their children and that are better for sons than for daughters, then they will have more boys. Conversely, if parents have any traits that they can pass on to their children and that are better for daughters, they will have more girls.

Physical attractiveness, while a universally positive quality, contributes even more to women's reproductive success than to men's. The generalized hypothesis would therefore predict that physically attractive parents should have more daughters than sons. Once again, this is the case. Americans who are rated "very attractive" have a 56 percent chance of having a daughter for their first child, compared with 48 percent for everyone else.

Here we come to the really interesting stuff. For example, if you Google "generalized Trivers-Willard hypothesis" you will find that it was created by ----add trumpet sounds here----Mr. Kanazawa himself! Yup. And the research is mostly his on this topic. A letter to the editor(pdf) at the journal where Kanazawa's papers were published (Journal of Theoretical Biology) addresses some of the problems in this research:

Dr. Satoshi Kanazawa has published several papers in
your journal recently finding evidence for differential sex
ratios, with big and tall parents, engineers, violent men,
and less attractive parents being disproportionately more
likely to have sons than daughters. As a statistician, not a
biologist, I cannot speak to the theoretical content of these
papers, but I believe the statistical arguments therein to be
seriously flawed. This is not to say that the results are not
scientifically correct, just that they have not been convin-
cingly demonstrated by the statistical evidence.

What this states, pretty much, is that Kanazawa failed to prove any of the theories he proposes. Perhaps he could do so in a better done study. But he has not done so yet. This is how scientists usually write, by the way. You have to understand that to see how very strong the criticisms of this letter are. (For somewhat easier-to-read versions of the same criticisms, see here and here.)

Here we come to the part where women are the cause of everything, even though they don't compete except in boob size:

7. What Bill Gates and Paul McCartney have in common with criminals

For nearly a quarter of a century, criminologists have known about the "age-crime curve." In every society at all historical times, the tendency to commit crimes and other risk-taking behavior rapidly increases in early adolescence, peaks in late adolescence and early adulthood, rapidly decreases throughout the 20s and 30s, and levels off in middle age.

This curve is not limited to crime. The same age profile characterizes every quantifiable human behavior that is public (i.e., perceived by many potential mates) and costly (i.e., not affordable by all sexual competitors). The relationship between age and productivity among male jazz musicians, male painters, male writers, and male scientists—which might be called the "age-genius curve"—is essentially the same as the age-crime curve. Their productivity—the expressions of their genius—quickly peaks in early adulthood, and then equally quickly declines throughout adulthood. The age-genius curve among their female counterparts is much less pronounced; it does not peak or vary as much as a function of age.

Paul McCartney has not written a hit song in years, and now spends much of his time painting. Bill Gates is now a respectable businessman and philanthropist, and is no longer a computer whiz kid. J.D. Salinger now lives as a total recluse and has not published anything in more than three decades. Orson Welles was a mere 26 when he wrote, produced, directed, and starred in Citizen Kane.

A single theory can explain the productivity of both creative geniuses and criminals over the life course: Both crime and genius are expressions of young men's competitive desires, whose ultimate function in the ancestral environment would have been to increase reproductive success.

In the physical competition for mates, those who are competitive may act violently toward their male rivals. Men who are less inclined toward crime and violence may express their competitiveness through their creative activities.

The cost of competition, however, rises dramatically when a man has children, when his energies and resources are put to better use protecting and investing in them. The birth of the first child usually occurs several years after puberty because men need some time to accumulate sufficient resources and attain sufficient status to attract their first mate. There is therefore a gap of several years between the rapid rise in the benefits of competition and similarly rapid rise in its costs. Productivity rapidly declines in late adulthood as the costs of competition rise and cancel its benefits.

These calculations have been performed by natural and sexual selection, so to speak, which then equips male brains with a psychological mechanism to incline them to be increasingly competitive immediately after puberty and make them less competitive right after the birth of their first child. Men simply do not feel like acting violently, stealing, or conducting additional scientific experiments, or they just want to settle down after the birth of their child but they do not know exactly why.

The similarity between Bill Gates, Paul McCartney, and criminals—in fact, among all men throughout evolutionary history—points to an important concept in evolutionary biology: female choice.

Women often say no to men. Men have had to conquer foreign lands, win battles and wars, compose symphonies, author books, write sonnets, paint cathedral ceilings, make scientific discoveries, play in rock bands, and write new computer software in order to impress women so that they will agree to have sex with them. Men have built (and destroyed) civilization in order to impress women, so that they might say yes.

Isn't it nice that suddenly women have choices? So far their choices have amounted to nothing but turning blonde and buxom. Now suddenly it is their say-so that causes civilizations to be built or destroyed! If only some woman had been merciful to Hitler...

Here the common fallacy of Evolutionary Psychology crops up, the tendency to equate the evolutionary pressures with people's actual desires. Leonardo da Vinci didn't go to work thinking that he will get laid if he paints well enough, and in any case he was most likely gay.

What about this theory or theorilette? (A nice word, that. I just invented it in my desperate desire to get laid.) It's true that some areas of creativity, such as mathematics, seem to favor younger men over older men. But other areas of creativity do not. I'm not sure if meaningful comparisons between women and men can be made here, given that women were not really able to practice their creative talents until quite recently, and even today they may be delayed by childbearing and child rearing.

Note, again, how unusual circumstances (such as using Bill Gates (the second richest man in the world) and Paul McCartney as examples) are somehow taken and made into the general way things are. Yet no evidence is offered that these men have more children than the average.

The last three points will be covered in Part 4.