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Archiver > GENEALOGY-DNA > 2005-06 > 1118118962


From: "Andrew and Inge" <>
Subject: RE: [DNA] Middle Eastern ancestral markers on new Euro 1.0 test
Date: Tue, 7 Jun 2005 06:36:02 +0200
In-Reply-To: <REME20050606154007@alum.mit.edu>


John Chandler wrote:
> I say again: the observation of a signficant difference in survival rate
*is* the operational definition of selective advantage.

That is simply wrong, and not just unsatisfying, because it is tautological.
Using the adjectives "statisical" and "operational" do not stop this from
being bad procedure. In a discussion about whether X causes Y, you are
*defining* observations of Y as "operational" observations of X.

>I clearly specified very early on that 1000 was a "large" population for
this purpose, and I gave another example of 2000 being "large".

Not really clear. I think I understood that you then went on to advise that
you could not actually say this exactly based upon population sizes like
this alone, because in reality it would be complicated. For example war,
famine etc could easily cause a different result. Am I right?

>> Could you offer any convincing arguments for any of the above assertions?
As
>> far as I can see war, famine, pestilence, small populations, and
occasional
>> periods with declining populations are perfectly normal in Iberian
history
>> and pre-history.

> You are referring to populations in the plural as if you could break up
Spain (or the Basque region) into village-sized groups that would drift
genetically in unison. True, a village-sized group can drift genetically,
or even disappear, but the composite of many such groups is a large
population that averages all those little drifts out.

Given the context, what is important is that famine etc *can* happen in the
population as a whole. And it is obvious that this is true, no? In fact
extremely localised famine sounds very odd indeed. So it is in fact you who
assumes something odd: that famine can only happen in one village at a time
for example. By the way, villages are a new invention and did not always
exist in Europe. In any case (a) I do not see that I assumed anything about
villages, and (b) Spain did not necessarily have a large population because
it was large.

>> what we were discussing was whether you *need* immigrations in order to
explain a big change in the haplotype population.

> And the answer is yes, unless you want to postulate a bottleneck.

Then the question remains "how do you exclude bottlenecks?" It seems to be
an arbitrary assumption that "the composite of many ["villages"] is a large
population that averages all [...] little drifts out" which is assuming
exactly what you need to assume in order to conclude what you want to
conclude.

Best Regards
Andrew

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