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Archiver > GENEALOGY-DNA > 2007-10 > 1191268170


From: "Elizabeth O'Donoghue" <>
Subject: Re: [DNA] East Anglia and the Vikings
Date: Mon, 1 Oct 2007 20:49:30 +0100
In-Reply-To: <REME20070930225432@alum.mit.edu>


John Chandler said:

'There is practically no difference in the
estimated TMRCA due to the differences of marker mutation rates...
Mathematically, the only really
significant factor is the *sum* of the mutation rates of all markers
considered, whether they mutatated or not.'

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John, I've seen you and probably others make this statement periodically. I
don't have the mathematical skills to easily test what difference there is
between TMRCA based on 'slow' vs fast' markers, but Family Tree does set
their calculator to take into account the varying mutation rates of each
marker when comparing individuals. I have seen where the GD of two
individuals varies, even if they have the same genetic distance but at
different markers. On occasion, I've seen a closer TMRCA for two
individuals with a greater genetic distance than two with a lesser distance
(granted it's usually just a difference of one). And it's not hundreds of
years, but it could be more than a hundred, even within a genealogical time
frame.

I know you discount Family Tree's mutation rates altogether, but the
principle should be the same, regardless of the specific rates used,
shouldn't it?

Also, I know you responded to me a bit ago mentioning a 500-1000 year scale
for using your own rates with 'fudge factors'. Could you see them being
stretched to 2,000 years?

Thanks much. Elizabeth

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