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Archiver > GENEALOGY-DNA > 2008-11 > 1227883689


From: Vincent Vizachero <>
Subject: Re: [DNA] TRMCA for R1b1
Date: Fri, 28 Nov 2008 09:48:09 -0500
References: <C556259C.FA4C%bobhay@optusnet.com.au>
In-Reply-To: <C556259C.FA4C%bobhay@optusnet.com.au>


I will oversimplify, but here's a short summary.

The "old theory" is that R-M269 entered Europe sometime around 25-30
kya ago, survived the LGM in the Franco-Cantabrian refugium, and
expanded to repopulated Europe immediately thereafter.

The "new theory" is that R-M269 entered Europe during the neolithic
era (i.e. sometime after 8 kya ago). Different people use slightly
different methodologies, but most TMRCA estimates for R-P311 (which
accounts for over 90% of R1b in western Europe) are in the range of
4-8 kya.

In short, the data are these:

1) the variance of STR haplotypes within the major western European
clades is very low: consistent with the new theory but not with the
old.
2) the variance of STR haplotypes is higher in southeastern Europe
and southwestern Asia than in western Europe: consistent with the
new theory but not with the old.
3) the oldest forms of R1b1b2 (those formerly called ht35 but which
now have SNP-based labels) are found progressively more frequently in
southeastern Europe and southwestern Asia than in western Europe:
consistent with the new theory but not with the old.
4) the rate of SNP accumulation (i.e. the Karafet et al. method) puts
the TMRCA for R1 overall at 18.5 kya. The TMRCA for R1b1b2 must, by
definition, be younger than that - and according to STR variance, MUCH
younger: consistent with the new theory but not with the old.


VV


On Nov 28, 2008, at 6:47 AM, Bob Hay wrote:

> For someone like me who is neither population geneticist nor
> statistician,
> it would be most helpful if, at this stage, someone would post a
> précis of
> the several TRMCA being postulated for M269 (and maybe its sub-
> clades). It
> would help too if the reasons for suggesting such ages could be
> outlined in
> lay terms.



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