The Red Queen_ Sex and the Evolution of Human Nature - Matt Ridley [63]
In some poor social classes, daughters are preferred even today. A poor son is often forced to remain single. But a poor daughter can marry a rich man. In modern Kenya, Mukogodo people are more likely to take daughters than sons to clinics for treatment when they are sick and therefore more daughters than sons survive to the age of four. This is rational of the Mukogodo parents because their daughters can marry into the households of rich Samburu and Maasai men and thrive, whereas their sons inherit Mukogodo poverty. In the calculus of Trivers–Willard, daughters are better vessels for producing grandchildren than sons.76
Of course, this assumes that societies are stratified. As Mildred Dickemann of California State University has postulated, the channelling of resources to sons represents the best investment rich people can make when society is highly stratified. The clearest patterns come from Dickemann’s own studies of traditional Indian marriage practices. She found that the extreme habits of female infanticide that the British tried and failed to stamp out coincided with relatively high social rank in the distinctly stratified society of nineteenth-century India. High-caste Indians killed daughters more than low-caste ones did. One clan of wealthy Sikhs used to kill all daughters and live off their wives’ dowries.77
There are rival theories to explain these patterns, of which the strongest is that economic, not reproductive, currency determines a sexual preference. Boys can earn a living and marry without a dowry. But this entirely fails to explain the correlation with rank. It predicts, instead, that lower social classes would favour sons, not higher ones, for they can least afford daughters. If instead, the production of grandchildren was what mattered, Indian marriage practices make more sense. Throughout India it has always been the case that women more than men can ‘marry up’ into a higher social and economic caste, so daughters of poor people are more likely to do well than sons. In Dickemann’s analysis, dowries are merely a distorted echo of the Trivers-Willard effect in a female-exogamous species: sons inherit the status necessary for successful breeding; daughters have to buy it. If you have no wealth to pass on, use what you have to buy your daughter a good husband.78
Trivers–Willard predicts that male-favouritism in one part of society will be balanced by female-favouritism elsewhere, if only because it takes one of each to have a baby – the Fisher logic again. In rodents, the division seems to be based on maternal condition. In primates, it seems to be based on social rank. But baboons and spider monkeys take for granted the fact that their societies are strictly stratified. Human beings do not. What happens in a modern, relatively egalitarian society?
In comparatively unstratified California, Hrdy and her colleague Debra Judge have so far been unable to detect any wealth-related sex bias in the wills people leave when they die. Perhaps the old élite habit of preferring boys to girls has at last been vanquished by the rhetoric of equality.79
But there is another, more sinister consequence of modern egalitarianism. In some societies, the preference for boys seems to have spread from élites to the society at large. China and India are the best examples of this. In China a one-child policy may have led to the deaths of seventeen per cent of girls. In one Indian hospital, ninety-six per cent of women told they were carrying daughters aborted them while nearly one hundred per cent of women carrying sons carried them to term.80 This implies that a cheap technology allowing people to choose the gender of their children would indeed unbalance the population sex ratio.
Choosing the gender of your baby would be an individual decision of no consequence to anybody else. Why then is the idea inherently unpopular? It is a tragedy of the commons: a collective