BTW, as I've mentioned before, Y-STRs tend to be volatile. A repeat could
be added in one generation and deleted in another. In the early days of
our testing, I thought we might be able to judge which of John's sons a
tester was descended from by determining his Y-STRs. But we had a lesson
in that a few years when we saw that William Matthews Cooley's descendant
*and* Jim Cooley--whose line had not yet been completed--both had 22
repeats at DYS438. Because of that match, I was becoming inclined to think
that Jim was descended from William. But Gloria found the genealogical
proof that Jim's John was the son of Perrin, not of William. Those 22
repeats told us nothing.
SNPs are different. Once a C changes to a T (or whatever), it tends to
stay that way for hundreds of generations. This difference is why FTDNA
gives *predictions* of haplogroups and why it's important that many of us
actually test our "terminal" SNP--which, presently is the 2300 year-old
L448.
So why do they do Y-STRs at all? There's information in their volatility.
We can make judgments about probable descent within about 15 generations.
The known SNPs are thousands of years old. But, the next question is, Why
are they becoming so topical? SNPs are an essential tool for population
genetics. Their antiquity tells the story about the ancient movements of
people. But SNP mutations happen regularly. I think I've read that there
are about 30 mutations on average per generation. Many of those happen in
coding regions, those area known as genes and where the recipes for
proteins are encoded. Natural selection does weird things with them. But
when it happens in the so-called "junk DNA" regions, they become part of
the vast "tree-ring" history of our DNA. Companies like FTDNA, who have a
vested interest in *close* genealogy, now have the means to test for vast
volumes of the newer SNPs. In time, we might very well find a SNP that was
inherited in the Y chromosome of John Cooley's germ cells. (Mutations in
non-germ cells are not inheritable.)
Anyway, that a Y-STR mutation was present in my germ cells and not my
dad's in purely academic--and a personal kick. But it also goes to show
that we need to be careful in our interpretations of Y-STRs. We can't get
the fine granular detail we once might have once expected.
-Michael
> Well, I always kind of knew it. :)
>
> I had two of my dad's Y-SNPs tested: the two that I have that are in
> variance with our Cooley clan's modal (average) haplotype.
>
> My DYS449 has 34 repeats. Dad's has the CF01 (our group's) value of 33
> repeats.
>
> DYS607, on the other hand, holds at 15 repeats--as opposed to the modal of
> 16 for almost all other testers in CF01.
>
> This means that although Don and I are a "genetic distance" of two, he and
> dad are a genetic distance of one--as Don and Jim are.
>
> I'm kit #57597 (a descendant of Edward) -- bottom from the last in the
> first group. Don (a descendant of James) is kit #N3690. Jim (a descendant
> of Perrin) is kit #160752:
>
> https://www.familytreedna.com/public/Cooley/default.aspx?section=yresults
>
> -Michael
>
>
--
Second VP, the Cooley Family Association of America
Administrator, the Akins DNA Project
Administrator, the Ashenhurst DNA Project
Administrator, the Bishop DNA Project
Administrator, the Eldridge DNA Project
Administrator, the Fisk DNA Project
Administrator, the alt-McDowell DNA Project
Co-Administrator, the Cooley DNA Project
Co-Administrator, the McDougall DNA Project
Instructor, the Osher Lifelong Learning Institute (OLLI)
B.A. Humboldt State University, History
Received on Thu May 08 2014 - 13:52:23 CDT