DNA-R1B1C7-L Archives

Archiver > DNA-R1B1C7 > 2007-11 > 1196095971


From: "David Wilson" <>
Subject: Re: [DNA-R1B1C7] Markers 38-67
Date: Mon, 26 Nov 2007 08:52:51 -0800
References: <001501c82ea4$855b3340$6402a8c0@DW1><200711241657.lAOGv8dl017302@mail.rootsweb.com>
In-Reply-To: <200711241657.lAOGv8dl017302@mail.rootsweb.com>


Hmm, good questions.

I think I might actually be suspicious if I found two people who were an
exact match at 37 markers, but who were no more than a 63/67 match when the
extra markers were tested. The reason is that there are several fast-moving
markers in FTDNA's third panel (26-37) and proportionally fewer in markers
38-67. Why would two presumably related people have no mismatches on fast
moving markers but several differences on a slow-moving set?

It seems likelier that one would find a 33/37 match that becomes a 63/67
match with extended testing simply because the last 30 markers are, as a
group, so stable. (Though one must acknowledge there are markers in the last
30 that are individually capable of showing significant variance in a large
enough population.)

In any event, it's generally true that the more markers you test, and the
fewer mismatches you see based on the markers that were tested, the greater
the probability of a recent common ancestor. Under any circumstances, a
four-step mismatch at 67 markers indicates likelier recent common ancestry
than a four-step mismatch at 37.

As to the presentation order of a match list, I understand your point but
doubt that FTDNA will adopt the suggestion. They already offer options on
their "preferences" tab that will let people suppress match lists that are
too inclusive, so it is possible to hide lists of matches that are
essentially irrelevant. For those with rare haplotypes, I think there is
perhaps some value in seeing the 12-marker matches first, as one gets a
sense of ever-refining evaluation as one works down the page. The names that
stay in each section catch one's attention as others drop out.

David Wilson



-----Original Message-----
From:
[mailto:] On Behalf Of Marie Kerr
Sent: Saturday, November 24, 2007 9:28 AM
To:
Subject: Re: [DNA-R1B1C7] Markers 38-67

David,

Thanks for your deep knowledge of the science of all this. One thing I'd
like to understand better--and this may be related to what you just
stressed--is that any 67 marker match implies a closer match than any 37
marker match. So, a person who matches at 67 -4 is more likely to be related
to my father than an exact 37 marker match. I have called FamilyTree DNA on
this and they confirmed. I also suggested that they list the 67 marker
matches on top because these are what I believe most people are most
interested in. Any based on their science, an exact 67 match implies a very
close generational match, so that person could have strong physical
similarities worth pursuing.

Thoughts?

Marie

-----Original Message-----
From:
[mailto:] On Behalf Of David Wilson
Sent: Saturday, November 24, 2007 9:16 AM
To:
Subject: Re: [DNA-R1B1C7] Markers 38-67

This was already addressed, but I wanted to reinforce the point more
generally.

Markers 38-67 are slow-moving markers, so for a given population the
variance will be less compared to the first 37 markers. It's not just
R1b1c7. In any haplogroup with a relatively compact distribution, two
individuals are likelier to lie closer to one another on the last 30 markers
than in the first 37.

David Wilson



-----Original Message-----
From:
[mailto:] On Behalf Of
Sent: Monday, November 19, 2007 10:45 AM
To:
Subject: [DNA-R1B1C7] Thanks for sparking the dialog.


The long silence was getting a bit to loud .Hey R1B1C7's if you want to
have some fun ? Create a new Y-search user by only plugging in the last 32
Markers of your 67 marker test .Set the limit to a genetic distance of 2
or 3.for comparing To bad but not all R1B1C7's use Y-search. Or simply
eyeball the R1B1C7. Haplogroup they appear to be closer in genetic distance
than other haplogroups when comparing only the last 32 markers, for some
reason.How strange is that?
G Ashley.





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