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Archiver > GENEALOGY-DNA > 2006-10 > 1159721036


From: John Lerch <>
Subject: [DNA] (no subject)
Date: Sun, 1 Oct 2006 9:43:56 -0700


You didn't quote the whole letter. As I mentioned in the bottom line, the only way out of the complete replacement of the A YDNA and A mtDNA is the back replacement of European DNA by A DNA--equivalent to your homogenization.
JAL
John C wrote
John wrote:
> First: let's suppose the percent of European autosomal chromosomal
> material is constant and that the fraction of European-AA mating is
> N. Then if the percent European DNA is 20 (very near according to
> DNAcousin's citation) then a SState (SS) would be achieved for N
> given by .2/2*(1-N) +N/2 =.2

If, by SS you mean "steady state", then there is no such thing in the
scenario you have described, until the entire population has been
homogenized. The fact is that the "lost" DNA at each generation is
apportioned very nearly according to its frequency in the population.
Therefore, you should not have the division by two in the above
equation. What this means is that, if the European subpopulation is
much larger than the African subpopulation, or is defined in such a
way that all mixtures are counted as "Africans", then the fraction of
African DNA in the "African" subpopulation will drop by a factor of
(1-N) *every* generation. That dropping will continue until either
the admixture of African DNA in the "European" subpopulation has risen
to meet the fraction found in the "Africans", or the "strictly European"
subpopulation has disappeared entirely because everyone has become
mixed.

John Chandler

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