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Archiver > GENEALOGY-DNA > 2007-07 > 1184055177


From: "Dennis Wright" <>
Subject: Re: [DNA] R1b1c7 as a calibration tool - The " final " version
Date: Tue, 10 Jul 2007 18:12:57 +1000
In-Reply-To: <BAEKIPDCJKIGDOPBOCPBOEEKDAAA.r.bootle@btinternet.com>


Bob,

The experts say the 'square-root' relationship is the correct one so we
should acknowledge that.
Several of the Irish Type III surnames branched off the O'Brien 'Heber' line
more than 1000 years ago. I think the founder of the cluster would have to
have lived prior to 900 AD, so I too am suggesting the squared-root method
using, until another figure is proved superior, the McEwan NWI TMRCA = 3362
(rounded off of course).

31 Marker Set Square Root Relationship holding McEwan's 3362
GroupGDMRCA yrsCalender
Irish Type III 3 1900 100 AD
R1b1c9a 4 3400 1400 BC
R1b1c7 4 3400 1400 BC
R1b1c6 6 8000 6000 BC
R1b1c9 8 13000 11000 BC
R1b1c 12 15000 13000 BC
R1b1 14 21000 19000 BC

So let's have some discussion on this model.

Dennis
*********************************************************

-----Original Message-----
From:
[mailto:]On Behalf Of Bob Bootle
Sent: Tuesday, July 10, 2007 5:30 PM
To:
Subject: Re: [DNA] R1b1c7 as a calibration tool - The " final " version


John Chandler wrote:-
It is just asking for trouble to present your results using two or
more imcompatible models when you know that at least one of them is
wrong. People will get the impression they are free to pick any
model, whichever comes closest to their preconceptions, but will not
likely be able to agree on one model.
...............................................................
My response :-
It was a group effort. If anyone cares what I think :-
I would prefer the McEwan figure of NWI TMRCA=3362.
I have not checked his work. I am trusting the man.
( not to four decimal places - perhaps we should correct him )

Secondly, there is good evidence that the square-root
relationship is the proper one. However, this can only apply
whilst it is undistorted by the ancient " population structure "
which, I suppose to be unknowable in detail.

Major distortions, such as the de-population of the British Isles
during the last Ice Age, the Younger Dryas, and perhaps the
agricultural expansion, are serious issues for any simple model.

In Britain, I don't know the significance of the 'Black Death'.

How much do you think
'a sudden halving of the population, which left many survivors sick'
would affect the simple prediction of a TMRCA ?

Regards

Bob


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