Ten Politically Incorrect Truths About Human Nature

By:Alan S. Miller Ph.D., Satoshi Kanazawa Ph.D.

4. Most suicide bombers are Muslim

According to the Oxford University sociologist Diego Gambetta, editor of Making Sense of Suicide Missions, a comprehensive history of this troubling yet topical phenomenon, while suicide missions are not always religiously motivated, when religion is involved, it is always Muslim. Why is this? Why is Islam the only religion that motivates its followers to commit suicide missions?

The surprising answer from the evolutionary psychological perspective is that Muslim suicide bombing may have nothing to do with Islam or the Koran (except for two lines in it). It may have nothing to do with the religion, politics, the culture, the race, the ethnicity, the language, or the region. As with everything else from this perspective, it may have 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.

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.

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.

Copyright belongs to Psychology Today.