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Archiver > GENEALOGY-DNA > 2008-10 > 1224077208


From: Vincent Vizachero <>
Subject: Re: [DNA] What is a clade?
Date: Wed, 15 Oct 2008 09:26:48 -0400
References: <006601c92e07$1a005d10$6400a8c0@Ken1><f3f05ce80810150353r13ced066y4b891e1a60542144@mail.gmail.com>
In-Reply-To: <f3f05ce80810150353r13ced066y4b891e1a60542144@mail.gmail.com>


For one thing, a haplotype is nothing but a description of a haploid
chromosome (or, in less precise usage, a haploid organism), so taking
what Dienekes wrote below literally would prevent ANY specification of
Y-DNA clades.

For example, P297+ M269+ S116- M73- etc. is a haplotype. Most people
would be happy to assign a chromosome with that haplotype to a clade
(R1b1b2), because the probability of a group of chromosomes having
that same haplotype and NOT descending from a common ancestor is
exceedingly low.

So why should it be impossible to ascribe a chromosome to its proper
clade based on a STR-based haplotype? In theory, it is not at all
impossible. In fact, we do it all the time. Supply a STR haplotype
of any decent length to this list, and there will be no shortage of
experts available to tell you with nearly 100% accuracy which
haplogroup that haplotype should belong to.

Remember, clades exist as a natural biological fact. Geneticists only
function to discover or map them, much like a cartographer might map
the geological features of a landscape. The course of the Mississippi
River is not "determined" by the mapmaker, at least not in the sense
of the mapmaker having any control over where it flows or does not
flow. And the course of the river remains the same whether I provide
an array of GPS coordinates, describe it as the second longest river
in the United States, or call it "that big river that flows through
Dubuque".

My point is that any description of a clade, as long as it is
reasonably accurate and precise, is legitimate. STR-based haplotypes
don't always meet that specification, but they sometimes do. And SNP-
based haplotypes do not automatically meet that specification, even if
they usually do.

VV

On Oct 15, 2008, at 6:53 AM, Dienekes Pontikos wrote:

> An haplotype-determined clade specification is impossible

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