

The ratio of boys to girls at conception has been misunderstood - DarkContinent
http://nautil.us/issue/27/dark-matter/this-gender-mystery-starts-nine-months-before-birth

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ronnier
Slightly off topic but the male/female ratio is very imbalanced in places.
Having just moved back to Seattle from Tokyo, this imbalance is very prominent
here, which wasn't noticeable in Tokyo. Just yesterday I went to a bar with a
colleague. I counted 21 males, 0 females. That type of ratio isn't uncommon
here it seems. A friend went to a yoga class with his girlfriend and he said
more than half the class was male. They also took salsa lessons together and
mentioned that men had to have other men as dance partners since there wasn't
enough women to pair up with.

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pavel_lishin
> _They also took salsa lessons together and mentioned that men had to have
> other men as dance partners since there wasn 't enough women to pair up
> with._

I wonder if this is mostly due to those men attending salsa classes hoping to
meet women.

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Jtsummers
Hoping to meet women, or develop a talent/skill that they can use to impress
women they meet elsewhere.

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skybrian
In case you're not into skimming through the history, here's the nut graph:

"Any sex ratio much higher than 108 (52 percent male) at any time during
pregnancy is essentially excluded by modern data. Past the middle of the
second trimester the sex ratio is known with great accuracy, at least in
industrialized countries with strong health systems and reliable vital
statistics, because nearly every fetal death after that point is recorded. The
sex ratio of 20-week fetuses is essentially identical to the secondary sex
ratio: The numbers of deaths after that point is too small to make much
difference, even if the stillborn were all male."

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ars
A note to the reader: this article has far more questions than answers. It's
still interesting, but know what to expect before you read it. Unlike some,
this author is very careful about understanding the limits of what we know.

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haberman
It seemed to make a pretty strong statement by the end: "The old story of high
primary sex ratio — as high as 282 (74 percent male) by some accounts —
declining rapidly and then steadily to birth, is gone. Any sex ratio much
higher than 108 (52 percent male) at any time during pregnancy is essentially
excluded by modern data."

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bjwbell
"Is the primary sex ratio the same in all human populations at all times?" At
least the secondary sex ratio naturally varies in human populations, being
lowest in African's and somewhat higher in most others, see [0] and many other
references.

Meiotic drive can effect which embryo's survive [1] & [2]. It's an
intragenomic conflict where one copy of a gene is passed on to offspring more
than the expected 50%.

[0]
[http://www.cdc.gov/nchs/data/nvsr/nvsr53/nvsr53_20.pdf](http://www.cdc.gov/nchs/data/nvsr/nvsr53/nvsr53_20.pdf).

[1] [https://westhunt.wordpress.com/2015/04/09/a-common-
variant-l...](https://westhunt.wordpress.com/2015/04/09/a-common-variant-
linked-to-chromosomal-errors/)

[2] [http://www.unz.com/gnxp/human-uniqueness-is-not-
unique/](http://www.unz.com/gnxp/human-uniqueness-is-not-unique/)

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phkahler
I see a problem. They use data from in vitro fertilization to conclude the
primary ratio is about 100. That's neglecting a part of the natural process
that could introduce a bias. While earlier on the author rejects a couple of
measurements due to their mutual inconsistency - even though they were both
above 100.

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zoul
I would say the ratio of boys to girls at the moment of conception is
practically always 1:1?

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delecti
The entire point of the article is that it isn't that clear.

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cpncrunch
No, the article is very clear that the ratio at conception is exactly 1:1 (or
incredibly close to it).

