GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2008-07 > 1216250781
From: "Dienekes Pontikos" <>
Subject: Re: [DNA] calibrating for common ancestor - QUESTION?
Date: Thu, 17 Jul 2008 02:26:21 +0300
That is precisely true, that is why it doesn't make sense to average
over the 5 estimates, since for example the I1 and the J estimate have
a long common component (CT to IJ). They aren't _independent_
estimates of the quantity in question (CT to now).
On Thu, Jul 17, 2008 at 2:11 AM, Ken Nordtvedt <> wrote:
> [[[[ Dienekes, I think you are deliberately trying to remain vague.
> When two relatively young clades (relatively recent separate MRCAs) are used
> to to estimate the age back to their joint MRCA who existed very long ago by
> comparison, most of the variance between each pair of haplotypes, one of the
> pair from clade A and the other of the pair from clade B, comes from the
> long common branch line that goes back from clade A MRCA to the joint MRCA
> and then forward on another branch up to clade B's MRCA. All N(A) N(B)
> pairs share this same branch length. So one is very close to doing an
> estimate for the TMRCA for a single pair of haplotypes --- just like
> genealogical applications except one or two orders of magnitude longer
> branch lines.
> There is basically a SINGLE estimate. And the confidence intervals are
> evaluated accordingly.
> There is the statistical noise in that dominant common and long "V" branch
> line, and there is the somewhat washed out statistical noise within the
> lifetimes of the two relatively young clades A and B. Ken ]]]]]
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Dienekes' Anthropology Blog
|Re: [DNA] calibrating for common ancestor - QUESTION? by "Dienekes Pontikos" <>|