

Reproductive biology: Girls on top - prat
http://www.economist.com/sciencetechnology/displayStory.cfm?story_id=15125173

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lmkg
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.

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teej
> fetuses (feti?)

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.

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btilly
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?

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NathanKP
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.

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rue
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._

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

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jkkramer
"It ain't necessarily so" is a common turn of phrase (also a song), which the
author was playing off.

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pvg
Right. <http://en.wikipedia.org/wiki/It_Ain%27t_Necessarily_So>

I'm not sure what crazed style nazi is downvoting you for being informative.
It's a common reference.

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quellhorst
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%."

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emil0r
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.

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simon_
<http://en.wikipedia.org/wiki/Human_sex_ratio>

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.

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teilo
+1 for the double entendre.

