DNA-R1B1C7-L Archives

Archiver > DNA-R1B1C7 > 2008-06 > 1213387905


From: Mitch <>
Subject: Re: [DNA-R1B1C7] General Question from rookie
Date: Fri, 13 Jun 2008 13:11:45 -0700 (PDT)
In-Reply-To: <e0d2d2870806130748l3188dea0v6542aae1ddfbeb00@mail.gmail.com>


Thanks David for your thoughtful and detailed response. Very helpful to my understanding of this interesting, complex and often puzzling subject.

--- On Fri, 6/13/08, David Ewing &lt;&gt; wrote:

From: David Ewing &lt;&gt;
Subject: Re: [DNA-R1B1C7] General Question from rookie
To:
Date: Friday, June 13, 2008, 10:48 AM

Mitch asks: "I'm R1b1b2e (R1b1c7) and I have enlisted a couple of my
cousins
who are direct descendants of my maternal grandfather and great grandfathers
to be tested. Good idea?"

Well, sure, Mitch. It is a good idea to get a few folks tested in any line
you might be interested in, but remember that since these are relatives in
your maternal line, there is no expectation that their Y-DNA should look
anything like yours. As for testing "cousins," in the Ewing project I
really
try to get third or more distant cousins tested to help work out branch
structure, and I actively discourage first cousins or closer from getting
tested. Brothers, first cousins, fathers and sons, etc. are very likely to
have identical haplotypes, so it is unlikely that you will learn much by
having more than one of a group of very close relatives tested, and there is
always the risk that you will discover an embarrassingly recent NPE, which
is not a can of worms that I would relish opening. Having results on several
more distant relatives in a line allows you to filter out the noise of
recent mutations and to get a clearer idea of the haplotype of their common
ancestor.

Mitch also says, "I guess I'm confused about the line "currently
published",
sounded like he might fit into a new category down the road that has yet to
be created. Adding the "e" (M222) gives more of a focused location.
R1b1b2
sounds much more general as far as area. Correct? I was also surprised
because I thought R1b1b2 was European and this family has lived in Lebanon
for generations and generations."

Be careful with this idea that haplogroups have locations, Mitch. To be
sure, haplogroups did originate somewhere in space and time, but while
identifying the place of origin for a haplogroup may be the Holy Grail of
anthropogenetics, there are dozens of constantly evolving hypotheses about
how to explain the present distribution of haplogroups in the world. It is a
fact that most of the haplotypes of western European men that have been
tested so far are in haplogroup R1b1b2*. It is also a fact that among
populations sampled so far, the greatest density of R1b1b2e has been found
in NW Ireland. It does not follow that R1b1b2* is "European" and
R1b1b2e is
"Irish." These are shorthand ways of speaking, or perhaps hypotheses
about
origins--though this stretches the definition of 'hypothesis' a bit.

As for "new categor[ies] down the road," be assured that there will
be
thousands, and that there will be no end to discovering them. It is likely
that my brother and I have an SNP that no one else in the world has, and
that each of us has an SNP that the other does not have. It is also
virtually certain that these will never be discovered, and if they were,
they would be of essentially zero interest to the larger community of
genetic genealogists. SNPs are interesting to the extent that they are
shared by enough, but not too many people, because this allows us to puzzle
out the branch structure of the tree. This project will never be finished,
so it doesn't make sense to wait for it. Maybe it does make sense to wait
before shooting our mouths off, but who wants to spoil the fun?

Finally (finally!), though it may be true that R1b1b2e has more regional
specificity than R1b1b2*, it is not necessarily the case that a haplogroup
characterized only by an "upstream" SNP has less regional specificity
than
one that is "fully characterized" by a long list of downstream SNPs.
Consider this possibility. Suppose that a caveman in haplogroup X1b had two
sons, and that one of them had a new SNP so became the founder of haplogroup
X1b1. Suppose further that the descendants of the X1b1 brother were
terrifically successful in reproducing and scattered over the earth, and
some of the branches ended up with new SNPs of their own. Meanwhile, the
descendants of the brother without the new SNP just hung on by a thread;
there were never very many of them, they all lived close together and none
of them who had new SNPs survived. Nothing changed about their DNA, but as
soon as anthrogeneticists began publishing SNPs, they got stuck into
haplogroup X1b*. Now if we sample widely, we will find all kinds of
subclades like X1b1a2b1f... in lots of places, some of them widely
scattered. But we would find X1b* only where the descendants of the second
brother lived. In this case X1b* would have very high regional specificity,
much more so than the subclades of X1b1.

David Ewing

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