Re: What makes a male/female ratio equal ??

From: Bill Taylor (w.taylor_at_math.canterbury.ac.nz)
Date: 08/15/04 

Date: 14 Aug 2004 23:08:39 -0700

AFAICS while not having followed the whole thread, no-one has yet come up
with the correct explanation for the 50/50 M/F ratio in mammals.
(And other species with similar lifestyles, i.e. that produce offspring
in smallish numbers taking a while to grow to maturity , allowing sexual
selection in adults.)

Yes, slightly more males are born in humans, so that the greater die-off
rate of (Y-defective) males ensures a 50/50 mix at puberty. Nature is
*always* going to arrange for this 50/50 mix, whatever it takes in the
way of X's & Y's, testosterone, horns, fancy feathers or whatever else.

Why? The answer is known to most evolutionary bilogoists, and should really
be more widely known by the intellectual subculture.

The answer is:- if the species starts to produce more of one sex, say more
males, then it is the *females* who (one way or another) will have the more
say over choice of partner, and the males who have to put up with whatever
they can get. (Curs will get dogs!) This means that the females will
choose those with good-survival characteristics, and produce more better
offspring. This in turn means that genes that want to survive had better
attach themselves to female-producing individuals. Genes attaching
themselves to male=producers will get short shrift in the selection stakes.

This means that the genes that survive best are those with more female
offspring; and so the balance returns. All this would take a while
to happen if something external altered the male-fenale balance.
But once it's under way, it stays clamped onto a species like glue.

"Dan Christensen" <dchris@allstream.net> wrote

> It may be more complicated than that. I read (I'm no expert) that X sperms
> are slower, but can swim farther. A newly released egg is thus more likely
> to encounter X sperms -- the Y sperms having previously exhausted themselves
> in a "sprint."

This leads to an interesting bio-joke. As you say, the Y-sperm are good
in a sprint, the X-sperm good in the long distance. So, if the male has
an especially long penis, the Y-sperm will win the (short) race, and male
children will result. But if the father has a very short penis then the
female-producing heavy X-sperm will win the long distance race.

So you can tell how big a *** someone has by the ratio of the sex of his
children!! I have two boys and no girls, BTW...

------------------------------------------------------------------------------
           Bill Taylor W.Taylor@math.canterbury.ac.nz
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                We share 98% of our genes with chimpanzees.
                We share 50% of our genes with our siblings.
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