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Archiver > GENEALOGY-DNA > 2005-03 > 1111186922


From: "Ken Nordtvedt" <>
Subject: Re: [DNA] SNP Question
Date: Fri, 18 Mar 2005 16:02:02 -0700
References: <5.1.0.14.2.20050318223809.02bcafe8@mail.btinternet.com>


The SNP really does not "confirm" R1b or any other haplogroup. It defines
the haplogroup. A SNP mutation is supposed to happen only once in the
history of modern man because the mutation rate is so slow. (If we found
the SNP to mutate just a few times in the history of modern man that would
not be fatal; it would just require a little more detective work to sort
everything out)

Some male thousands of years ago has a SNP mutation. If his descending line
is very successful we see millions of his descendants today carrying that
SNP mutation. That defines a haplogroup. That founder lived say 10,000
years ago. He had a unique set of repeat values at all his markers. All
his descendant lines up to today have marker repeats that had "only" those
10,000 years to mutate away from each other rather than the much longer time
that modern man's haplotypes taken as a whole have had to diverge. As a
consequence, with a little experience and work at it many people can
recognize a haplotype's haplogroup membership by looking at the repeat
numbers. Some markers are more powerful than others in being relatively
unique to particular haplogroups. The more markers you have measured the
better the chance to make a highly reliable selection of its haplogroup;
there are more unique markers which point toward specific haplogroup.

At the physics and chemistry of it there is no causal relationship between a
mutation at a SNP and a mutation at a STR marker --- that is unless a
powerful cosmic ray passed through and caused both to occur. The same can
be said for mutations at different STR markers. They are independent,
probabilistic events.

Ken
----- Original Message -----
From: "THJ" <>
To: <>
Sent: Friday, March 18, 2005 3:42 PM
Subject: [DNA] SNP Question


> As an interested observer rather than an expert, could I ask an obvious
> question.
>
> What is the causal relationship between the set of markers indicating R1b
> and the SNP value which confirms R1b?
>
>
> Terry HJ
>
>
>
>
> ==============================
> Search Family and Local Histories for stories about your family and the
> areas they lived. Over 85 million names added in the last 12 months.
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