GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2007-03 > 1174589375


From: "Steven Bird" <>
Subject: Re: [DNA] Cruciani and 2007 TMRCA estimates
Date: Thu, 22 Mar 2007 14:49:35 -0400
In-Reply-To: <KHEKIJEABJGJEKDPFEDMOEFKDGAA.elizabethod@eircom.net>


Elizabeth,


Zhivotovsky's basic process is explained in:

http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1181912&blobtype=pdf

which is available free. This is the one in which he addresses Forster's
process directly.


The Dec 2006 paper is not yet available on the web, AFAIK. It represents a
refinement of the 2004 model.


>From what I can gather, the "evolutionarily effective mutation rate" differs
from the father-son transmission rate due to the nature of the population's
evolution itself. So mutation rates for pedigree-length calculations (i.e.,
up to say 10 or 15 generation) are much faster than population rates
extending for 80 or more generations, in part due to the nature of the
population's growth itself over longer periods of time.

HTH,

Steve







>From: "Elizabeth O'Donoghue" <>
>Reply-To:
>To: <>
>Subject: Re: [DNA] Cruciani and 2007 TMRCA estimates
>Date: Thu, 22 Mar 2007 18:29:36 -0000
>
>John McEwan explained that:
>
>1. 'Oppenheimer used Forster et al's (2000) "effective" mutation rates'
>
>2. 'Cruciani used an estimate from Zhivostovsky et al (2006)'
>
>3. 'observed father son rates' are 10x and 3x higher, respectively
>
>And there are other rates such as John Chandler's as well.
>
>I first want to thank John and others who have responded to my earlier
>inquiries about TMRCA, but I am still searching for some semblance of order
>and continuity to the whole subject. While #3 seems to be based on 'real'
>statistics, I wonder how many father-son comparisons were made to arrive at
>those rates. I wonder how Forster and Zhivostovsky arrived at their rates.
>I wonder what years/generations was used and what SD applies to any of
>these
>rates. As well, in principle, I don't see why there should be any
>difference between comparing short or long distances when deciding what
>rates to use - do the odds increase when you look longer?
>
>Partly because my DNA project is with Family Tree, and partly because I
>suspect a good number of other group administrators who follow this list
>also are based there, I must continue to wonder why so many consider FT's
>mutation rates as too short, since the database they have available to them
>in determining the rates they use is probably much larger than other
>studies - maybe I'm wrong. I don't know why they don't publish their
>results - I'm asked about it a number of times.
>
>It appears most Group Admin's - at FT anyway - use the FT TiP calculator
>when compiling results for their projects. What credence can we provide in
>reporting to our participants the results we are producing, when the larger
>community suggests their calculations are inadequate? A number of projects
>I have reviewed (mainly Irish/Scottish, I admit) are seeking answers to the
>origin myths of their ancestors - while they are usually still A.D., we may
>be going back 2000+ years. I know that Family Tree has less confidence in
>they calculations past about 600 years (24 generations at 25 years), so
>what
>do we do?
>
>Dean McGee's Y-Utility does not offer a TMRCA for the whole dataset input,
>does it? What options do we have in that regard? What minimum number of
>records should you have for comparison to expect an MRCA to have validity?
>I did receive an excel spreadsheet with formulas using STDEV and
>Zhivotovsky's rates. If there is a standard deviation to consider with his
>rates, what is it?
>
>I'm still wishing you'd all come to Ireland for a conference and agree to
>SOMETHING for us all... :-)))))
>
>I value your expertise and appreciate your help.
>
>Elizabeth
>
>
>
>
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