Two interesting stories that bump up against each other: radical life extension and mothers who expect lengthy lives tend to produce sons. I've talked about the first many times, including some speculation on how society would change if we lived drastically longer lives. The second says:
Mothers who think they have longer to live are more likely to give birth to boys than girls, a survey of British women shows. The finding backs up the long-held theory that women may unwittingly be able to influence the sex of their unborn child.Oddly, it may also be that having a baby boy causes mothers to think they'll live longer than mothers who have girls. Still, it's an interesting correlation. If everyone starts living much longer, will girls become more rare? I certainly hope not!Sarah Johns from the University of Kent asked 609 first-time mothers, who had already given birth, to guess when they thought they would die. By subtracting the mother's age, she then calculated the number of years each woman thought she had left to live. The results are reported in the Proceedings of the Royal Society1.
As the number of perceived years left rose, so too did the chance that they had had a son. Every extra year on the clock increased the odds of producing a male by 1%.
Of course, once we have radical life extension we'll probably also be able to select the genders of our children... would that be acceptable if the ratio of men to women got dramatically skewed? As I've noted before, countries and cultures with more men than women tend to be seriously screwed up.
My hypothesis: The traditional point of wanting sons instead of daughters was to have more soldiers. Counterbalancing that was war, which would kill off lots of men. Maybe the countries that have been selecting sons over daughters are just overdue for a war---and maybe all those desperate unmarried men will help start one.
This is related to polygamy, which makes perfect sense if your society has fought so many wars that you're running out of men and have an excess of women.
Once we have full sex selection, I wonder which sex people would prefer in which countries. It would probably change periodically, e.g.: If someone had perfected child sex selection ten years ago, the ratio of chosen sons to chosen daughters probably would have gone up in America after 9/11. Had the technology existed at the height of feminism in the seventies, no doubt that ratio would have gone down.