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Archiver > GENEALOGY-DNA > 2009-06 > 1243940583


From: Vincent Vizachero <>
Subject: Re: [DNA] revised TMRCA calcuations for the R-L21 results
Date: Tue, 2 Jun 2009 07:03:03 -0400
References: <64423.15901.qm@web81107.mail.mud.yahoo.com>
In-Reply-To: <64423.15901.qm@web81107.mail.mud.yahoo.com>


On Jun 2, 2009, at 1:22 AM, Gary Felix wrote:

> TMRCA for Y and Mtdna should theoretically go back almost to genetic
> Adam and Eve respectively.

Sure, but the the TMRCA estimates need not be identical (or even
similar) this there is no a priori reason to presume MRCA-Y and MRCA-
mtDNA were contemporaries of each other. That is, there is nothing
that dictates they lived in the same time or place.

> Therefore we are dealing with a genetic component which is prone to
> bias (drift) yielding TMRCA that are too low.

No. The lower effective population size (assuming that Crawford is
even right on this point) would cause the TMRCA to be lower in
reality. Lower TMRCA estimates are reflecting the reality, not a
distortion of it.

VV



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