Reproductive biology: Girls on top

FYI for people who may be confused by terminology: in the biological sciences, the word "abortion" refers to any termination of pregnancy, natural or otherwise, displacing the non-technical term "miscarriage." The medical procedure is usually qualified with adjectives such as "induced," or occasionally "elective." I don't want anyone to skim the article and think that women are getting elective abortions on male embryos. The article is saying that the natural miscarriage of male embryos & fetuses (feti?) is more sensitive to environmental stress than that of females.

A long time ago I saw research on boys born in Berlin from WW II that found that stress in mothers during pregnancy lead to an increased incidence of homosexuality. I wonder if there is a possible correlation.

For instance could it be that the stressed out mom flushes the fetus with female hormones to give a girl a better start in adverse circumstances, but those hormones increase the odds of abortion or homosexuality in boys?

That certainly is surprising. I know some research has suggested that a stressed mother is less likely to conceive in the first place. This is the first I had heard of stress leading to spontaneous abortion.

Once again I find myself wishing that less active tone was used of evolution.

It is not that more girls are born because they have a better chance of reproducing in a famine or other stressful condition; it is that genomes that exhibit this tendency have become prevalent precisely because of that effect, which is why we see it now.

Excellent article, but I was completely overthrown by the use of the word "ain't" (with an apostrophe, too). Quite atypical of The Economist.

Girls are on top yet more boys are born even in stressful times? "Over the whole period 52.4% of births were of boys. In some months, though, that fell as low as 51.2%."

+1 for the double entendre.