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From:
Subject: Re: [DNA] Progression of Haplogroups -- Observation; Tests
Date: Fri, 28 Oct 2005 14:53:46 EDT


In a message dated 10/28/05 9:35:58 AM Pacific Daylight Time,
writes:

> The yDNA haplgroup chart at EA shows that --
> C precededed I, which preceded J, which preceded O, which preceded Q and R,
> and then R1b.

The phylogenetic trees aren't drawn on a time scale. I actually find the tree
style of presentation visually deceptive, compared with a network diagram,
but it's so seductive that I have to keep reminding myself. For an example of a
network diagram, the Seven Daughters of Eve for mtDNA shows what I mean --
you're not tempted to say that K is older than H or vice versa, for example:

http://oxfordancestors.com/images/pdf_sevendaughters1.pdf

The only time you can sort by age is when haplogroups are shown as divisions
of a single haplogroup -- e.g. Q and R share the mutation that defines P, so P
is older than Q and R, but we don't know from the tree diagram whether Q or R
is older. G, H, I, J and K came after F, but we don't know in which order. If
K is very much older than the others, it's quite possible that branches off
of K like P, or even Q and R, are older than I and J.

Age estimates rely on other factors, such as the amount of variation which
has developed within a group, and they are very, very fuzzy.

Ann Turner



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