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.
I believe the convention for -i/-es pluralization is based on the Latin root of the word. In this case the correct version is "fetuses". I don't mean to correct - I figured I'm not the only one with a dash of language nerd in them.
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.
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%."
On average there are 105 boys born for every 100 girls. I believe it evens out in the end with more boys dying in an early age than girls, but I don't have any hard data on that.
I believe it doesn't even out until relatively late late in life, with male mortality being slightly higher at all ages. From the wikipedia article:
The "First World" G7 members all have a gender ratio in the range of 0.95–0.98 for the total population, of 1.05–1.07 at birth, of 1.05–1.06 for the group below 15, of 1.00–1.04 for the group aged 15–64, and of 0.70–0.75 for those over 65.
