GENEALOGY-DNA-L Archives

Archiver > GENEALOGY-DNA > 2009-12 > 1260648914


From: "Tim Janzen" <>
Subject: Re: [DNA] R-U152 and R-L21 on the European Continent
Date: Sat, 12 Dec 2009 12:15:14 -0800
In-Reply-To: <FD72FA3C9ED943C6A667D25EA898A1CD@anatoldesktop>


Dear Anatole,
Thanks for your response. I will respond to your items in the order
you numbered them.
1. If John overcounted mutations for some markers such as DYS426, shouldn't
that have resulted in him having calculated a higher mutation rate than the
true mutation rate? Note that when I do TMRCA estimates for Y Adam using
only the slowest mutating markers, I get an older age for Y Adam than I
think is probable. Thus, my theory is that some or many of John's mutation
rates for the slowest mutating markers are too low because John either
undercounted mutations for the slowest mutating markers or there is some
other variable here we haven't yet accounted for.
2. My response to this paragraph is that using too many fast mutating
markers in interclade TMRCA calculations results in TMRCA estimates that are
too low. I think that I demonstrated that in my original Y Adam
calculations which may be seen at
http://archiver.rootsweb.ancestry.com/th/read/GENEALOGY-DNA/2009-03/12376891
68. For those calculations I included a group of 50 markers from the
67-marker FTDNA panel. Note that when using these 50 markers, I got an
average estimated age of Y Adam at about 55,000-60,000 years when comparing
data from most haplogroups to haplogroup A. I think that this is somewhat
lower than the probable true age of Y Adam. In my opinion, the primary
reason that these estimates appear to be too low is that a relatively large
number of faster mutating markers were used in the calculations and their
variance was saturated.
3. The message I was thinking of in regards to your calculation of Y Adam
was this one:
http://archiver.rootsweb.ancestry.com/th/read/GENEALOGY-DNA/2009-03/12377480
10. My memory was incorrect. You calculated the age of haplogroup A as
being 75,000 years, not the age of Y Adam. In any case, your estimate (at
that time) of the age of Y Adam would thus by necessity be older than 75,000
years. It would appear that your techniques have changed if you are now
calculating a TMRCA for haplogroups A and B as being 36,700 years ago. It
seems probable to me that your more recent estimate is too low and that the
true age of the TMRCA for haplogroups A and B is more likely to be somewhere
in the 70,000-150,000 year range. What changed in your technique that
resulted in you substantially lowering your estimate of the age of
haplogroup A between March and now?
Getting to a truly accurate age of Y Adam is a tough challenge.
When we get a broader selection of complete Y chromosome sequences, it
should be easier because then we can use the SNP counting method to provide
us with an additional method because simply using STR data. In any case,
even then, we are going to need to use a selection of sequences from Native
Americans and Australian Aborigines from haplogroups Q and C which can be
used to help determine how many SNPs occurred between the two best
documented early geographic separations (the immigration of Native Americans
into N. America ca 15,000 years ago or so and the immigration of Australian
Aborigines into Australia ca 40,000 years ago).
Sincerely,
Tim

-----Original Message-----
From:
[mailto:] On Behalf Of Anatole Klyosov
Sent: Saturday, December 12, 2009 6:09 AM
To:
Cc: Anatole Klyosov
Subject: Re: [DNA] R-U152 and R-L21 on the European Continent


Dear Tim,

There are (at least) three items following from the above quotation: (1)
accuracy
of John Chandler's mutation rate table, (2) significance of that possible
inaccuracy,
if anything, for TMRCA estimates, and (3) "age" of Y Adam.

(1) If John has pulled together all, say, DYS426 mutations from, say,
YSearch
database, there certainly was an overcounting on the reason I have explained
earlier.

(2) Is it significant for TMCRA estimates? Not at all, if, for example,
FTDNA panels
are employed in their entirety, or just slightly abbreviated. Those the most
slow
markers do not contribute much when considered in that "blender" of both
fast
and slow markers. However, if only slow markers are used, it is a big deal.
It is a huge margin of error, probably no less that 100% or more.

(3) I do not remember my "best estimate" of "age" of Y Adam. I doubt if I
have or ever had any. I have tried to do my best with haplogroups A and B,
but bumped onto a severe bottleneck for haplogroup A ~28,000 ybp
(technically I got 28,200 ybp, with 107 of 37-marker haplotypes from
YSearch). A similar story was with haplogroup B, ~26,000 ybp (technically
25,900 ybp, with only 15 of 25-marker haplotypes from YSearch). THEIR common
ancestor, of haplogroups A and B, lived 36,700 ybp.

Anatole Klyosov



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