DNA-R1B1C7-L Archives

Archiver > DNA-R1B1C7 > 2009-04 > 1240711085


From: "Ken Nordtvedt" <>
Subject: Re: [R-M222] Walk on the Y Project
Date: Sat, 25 Apr 2009 19:58:05 -0600
References: <c89.461afc21.372509d1@aol.com>


You probably have the advantage of there being other walk the y dna being
tested and which comes from L21 clades other than M222? It is a M222
compared to that other dna which can find an snp which possibly further tags
another clade of L21. Your clade already has its M222 tag.

But two M222 dna samples only make sense for finding a new snp downstream of
the M222 MRCA and which divides M222. If the MRCA of M222 lived 1800 years
ago, then your two M222 dna samples search a maximum of 3600 years of branch
length. That's 120 generations. 120 divided by 500 gives about 1/4 --- the
chances of finding such an snp. And that snp even stands a good chance of
representing just a small fraction of M222. However, you are getting
sufficiently close to the quasi-genealogical era that even such a far
downstream snp would probably be of interest to those who are derived for
it.

The guiding principle I use in searching for new snps within a haplogroup is
this: the deeper in time the branch line(s) connecting my tested dna
samples go the better my chances. Divide total branch length in generations
by 500: that's your odds. Given I want to maximize branch length being
searched, I want the segments of that branch length as empty of existing
snps as possible. Finding redundant or equivalent snps is not the goal.
With several dna samples being tested, nothing is gained by testing the same
branch segments of the tree over again (assuming the search process is
efficient). So pick dna samples so new and different branch segments are
tested when adding additional dna donors.

After that it is best to just draw out the tree to the best of present
knowledge showing the connections between the present day dna samples being
tested, and with all the already known snps placed appropriately in that
tree. Then that sketch can give you some idea of chances of finding a
useful new snp.




----- Original Message -----
From: <>
To: <>
Sent: Saturday, April 25, 2009 6:50 PM
Subject: Re: [R-M222] Walk on the Y Project


>n a message dated 4/25/2009 7:07:25 P.M. Central Daylight Time,
> writes:
>
> Do you realize how small (or large, depending on perspective) your
> chances
> are of finding a new snp within M222?
> It's a rather young clade.
>
> Yes I do. If they find anything at all I expect it might be some SNP
> that
> further divides L21. That's why I wanted Thomas Krahn's opinion on a
> possible third test. What's your opinion on that? Would one self funded
> test
> be sufficient? Two?
>
>
> John
>
>
>
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