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From: "Dienekes Pontikos" <>
Subject: Re: [DNA] What is a clade?
Date: Wed, 15 Oct 2008 13:53:27 +0300
References: <006601c92e07$1a005d10$6400a8c0@Ken1>
In-Reply-To: <006601c92e07$1a005d10$6400a8c0@Ken1>


An haplotype-determined clade specification is impossible

A clade specification is valid if it can identify Y chromosomes that
share common descent _at the exclusion_ of other Y chromosomes.

Suppose you have devised a test T to determine whether a Y-chromosome
belongs to the clade or not. Suppose that the clade founder F lived G
generations ago. The test T, should be powerful enough to identify
members of the clade despite G-generations worth of mutations. But, by
symmetry, this test would also (erroneously) identify G-generations
worth of ancestors of F as members of the clade.



On Tue, Oct 14, 2008 at 5:13 PM, Ken Nordtvedt <> wrote:
> "Haplogroup" has been enlisted as the name for a clade identified by its members sharing some up-til-now basically unique mutational states, most often ydna or mtdna SNP mutations. This is rather straightforward. Clades can also be identified when member haplotypes show several unique STR repeat values which the probabilities show most likely indicate descent from a relatively recent common ancestral haplotype.

--

Dienekes' Anthropology Blog
http://dienekes.blogspot.com

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