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Archiver > DNA-R1B1C7 > 2012-01 > 1325609271


From:
Subject: Re: [R-M222] analysis
Date: Tue, 3 Jan 2012 11:47:51 -0500 (EST)


In a message dated 1/3/2012 10:25:18 A.M. Central Standard Time,
writes:


"Modal"... is a non-information to me. It might be the base haplotype, it
might be not. Hence, it does not give me anything, unless it is concluded
(employing certain criteria) that the dataset contains haplotypes descended
from one common ancestor. In that case model = base."




It's interesting that you posted that just as I was reading that portion
of his paper.





"An average number of STR mutations per haplotype
can serve to calculate the time span lapse from the
common ancestor for all haplotypes in the set, assuming
they all derived from the same common ancestor and all
belong to the same clade. That ancestor had a so-called
base, or ancestor (founder) haplotype. However, very
often haplotypes in a given set are derived not from one
common ancestor from the same clade, but represent a
mix from ancestors from different clades.

Since this concept is very important for the following
theoretical and practical considerations in this work, it
should be emphasized that by a “common ancestor for
a series of haplotypes” we mean haplotypes directly
discernable from the most recent common ancestor.
Such series of haplotypes are called sometimes “a cluster,"
or “a branch," or “a lineage." Each of them should
have a founding haplotype motif, and the founding
haplotype is called the base haplotype. Each “cluster,"
or “branch," or a “uniform” series of haplotypes typically
belong to the same haplogroup, marked by the
respective SNP (Single Nucleotide Polymorphism) tag,
and/or to its downstream SNP’s, or clades.

Granted, any given set of haplotypes has its common
ancestor, down to the “Chromosomal Adam." However,
when one tries to calculate a time span to a [most
recent] “common ancestor” for an assorted series of
haplotypes, which belong to different clades within one
designated haplogroup, or to different haplogroups, he
comes up with a “phantom common ancestor." This
“phantom common ancestor” can have practically any
time span separating it from the present time, and that
“phantom time span” would depend on the particular
composition of the given haplotype set."


>From reading this I assume that if you compare two different clusters of
people and you're not absolutely sure they have a common ancestor than you
might be creating a phantom. That would apply to sub-clusters within M222.



John







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