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Archiver > GENEALOGY-DNA > 2005-06 > 1118377771


From: (John Chandler)
Subject: Re: [DNA] The selective advantage debate
Date: Fri, 10 Jun 2005 00:29:31 -0400 (EDT)
References: <BKEPIIDHHKEPCMDIEBKBAEODCHAA.andrew.en.inge@skynet.be>
In-Reply-To: <BKEPIIDHHKEPCMDIEBKBAEODCHAA.andrew.en.inge@skynet.be>


Andrew wrote:
> I know this will sound obvious but this is only true in the sense that this
> is a tool. What we are talking about is reality, and specifically the past.
> In this case when you say statistics you are including probability models
> which contain assumptions about the past which you are trying to recreate.
> You yourself have admitted that fluctuations in the size of the population
> could have a big effect,

You still are ignoring or twisting everything that doesn't fit your
preconceived notions. There is ONE model with ONE assumption in my
last message: that the starting population of Iberia 10,000 years ago
was at least 100,000. If you don't believe that one assumption, say
so. Otherwise, you're stuck with the package. The point is, as I
explained in the previous message, that the "big effect" (a
bottleneck) leaves a footprint: loss of genetic diversity. If you
can't point to such a loss, you can't assume any of the other effects
of a bottleneck. It's that simple.

> I realise you are very sure of this. But I have then asked you is how you
> can tell so much from current statistics - for example how do you
> distinguish immigration effects and bottlenecks. You have stated for example
> that there were obviously no bottlnecks, no significant war, pestilance etc,
> and that the population must have been consistently large because Iberia is
> large.

Find the evidence of a bottleneck first. If you can't, then the
population must indeed have been consistently large. (Or else the
pre-bottleneck population was replaced by immigrants. That's one
option that can't be ruled out just by studying the modern
population.)

John Chandler


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