Archiver > GENEALOGY-DNA > 2005-07 > 1121268073

Subject: Re: [DNA] Relevance of SNPs to Genealogical Time Frame
Date: Wed, 13 Jul 2005 11:21:13 EDT

In a message dated 07/11/05 8:49:44 PM Pacific Daylight Time,

> John....
> "..At this very moment, there are many thousands of living individuals
> carrying the SNP for "R1b" who are not R1b, or who do *not* carry the
> SNP and *are* R1b...."
> We are saying here... How can one be R1b as defined by the YCC convention
> with SNP R1b-M343...and not be M343 ?

John is being his customary rigorous self. If SNPs were absolutely positively
beyond a doubt Unique Event Polymorphisms (UEPs), which occur only once in
all of human history and then never revert back to the original state, then it
would be safe to say that a positive SNP test for M343 would always be an
indicator of R1b.

But although the mutation rate for SNPs is usually given as .00000002, which
makes it a very rare occurrence, we do have counter-examples to uniqueness,
e.g. SRY10831 is a case where a mutation occurred very early in human history
and then reverted to its original state in Haplogroup R1a. If/when we can test
the billions of men on the planet, and if/when we can test millions of SNPs, we
are bound to find more and more counter-examples that show that SNPS are not
absolutely unique.

However, in more practical terms, I doubt John would spend bundles of money
to test other upstream SNPs if he received an M343+ result.

Ann Turner

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