Re: [BBC] Genetic 'Adam never met Eve'

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From: Dave Long (
Date: Wed Nov 01 2000 - 10:25:45 PPET

> But the finding raises new questions, not least because our most recent
> paternal ancestor would have been about 84,000 years younger than our
> maternal one.

So the coalescence time for males lines is shorter than that for
female ones, implying a higher fanout for male lineages? Now,
I'm no Wilt, but finding that male reproductive success has a
peakier distribution than female doesn't surprise.

> fathers children by several of her female descendants. Eventually, all the
> children of men other than "Adam" die out -- maybe his kids are meaner,
> stronger, and more immune to something important.

or maybe time and chance happen to them all. Does anyone have an
estimate for the population size circa 70kbc? Between that and a
figure for number of generations (3200 sounds low to me, but we
wouldn't be off by more than a factor of two with it), we ought to
be able to decide if "Adam"'s genes were actually selected, or if
entropy alone can explain their fixation.

The selection hypothesis is probably correct; unless the population
was only a couple of thousand individuals around that time, there
haven't been enough generations for fixation by genetic drift in
the recent case. What about at 150kbc? That's not so clear; it's
not always appropriate to ascribe simple darwinic causations when
ecclesiastesic ones suffice.


(It's interesting the consider the difference in mating strategies
as applied to the interests of bondholders vs. shareholders, or to
the existence of a political axis which has one endpoint believing
that promiscuity in finance leads to danger while promiscuity in
morals does not, and the other believing the opposite. Were there
a sizable population of libertarians, would the same factors that
drive development of anisogamous organisms from isogamous ancestors
produce a balancing population of religious fundamentalists?)

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