GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2012-02 > 1329388883


From: "Anatole Klyosov" <>
Subject: Re: [DNA] Out of Africa
Date: Thu, 16 Feb 2012 05:41:23 -0500
References: <mailman.2928.1329371931.1055.genealogy-dna@rootsweb.com>


> From: "Tim Janzen" <>

Dear Tim,

Thank you for your wise comment.

Regards,

Anatole Klyosov

************************************

> Thanks for running new calculations for haplogroup A. In 2009 I ran
> similar TMRCA estimates using the haplogroup A and B 67 marker haplotypes
> that were available at that time. See
> http://archiver.rootsweb.ancestry.com/th/read/GENEALOGY-DNA/2009-07/12473842
> 75 for background. We have discussed the issue that the variance of
> faster
> mutating markers will become saturated as you start to run TMRCA estimates
>on older haplogroups and subclades on this list on and off since 2009. The
> saturation of the variance can significantly lower the TMRCA estimates as
> illustrated in the message above. Dienekes reviewed this in his blog in
> 2010. See
> http://dienekes.blogspot.com/2010/12/how-old-is-y-chromosome-adam.html.
> Using 26 markers you calculate a TMRCA of 160,000 years for the A1a/A3a
> split. Using 24 markers in 2009 I calculated the A/B split at 147,246
> years. Anatole has said that he estimates that the common ancestors of
> haplogroups A and B are separated by 120,000 years and that the African
> and
> non-African lineages coalesce only at the alpha-haplogroup, around 160,000
> years ago (or earlier). These estimates are reasonably consistent with
> each
> other.
> I agree that use of SNPs for long-period clocking would be very
> helpful. However, the primary problem with this method is that the clock
> has to be rooted in some fashion. Karafat arbitrarily rooted the CT node
> at
> 70,000 years (See http://genome.cshlp.org/content/18/5/830). However, we
> can't be certain that the CT node really occurred 70,000 years ago. I am
> hopeful that DNA from one or more ancient male Homo sapiens skeletons will
> eventually be completely sequenced and that the skeleton can be accurately
> dated so that the Y SNP tree can be accurately rooted based on those
> results.
> Sincerely,
> Tim Janzen


This thread: