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Archiver > GENEALOGY-DNA > 2008-05 > 1210975262


From: Alan R <>
Subject: Re: [DNA] age of U152/S28
Date: Fri, 16 May 2008 22:01:02 +0000 (GMT)


I see what you mean. The SNPs are just things that happen along lines and dont begin the lineage itself or indicate movement in themselves. I would certainly be interesting to have a nice line of dated MRCA nodes going from the sub-sub clades back to something like R1. My own interest is what the dating tells us about prehistoric population movements. Late MRCA dates for fairly localised clades of western R1b1c dont trouble me too much as the distribution of a number do suggest localised origins. I would be very interested in the MRCA dates for all western R1b1c, for all R1b1c (east and west) and I suppose back to R1b and R1. Do you have figures for those? A lot of stuff has been posted but it would be very useful to see the sequence of MRCA dates arrived from the same technique side by side.

Alan

----- Original Message ----
From: Ken Nordtvedt <>
To: Alan R <>;
Sent: Friday, 16 May, 2008 10:29:00 PM
Subject: Re: [DNA] age of U152/S28

This is what trees with as many of the nodes (MRCAs) dated for age as
possible do --- confine SNPS between a node prior to their existence and
after their existence. But why do you want SNP ages? (I can answer my own
question but I won't at the moment). The dates of the nodes are the
important thing.

Ken
----- Original Message -----
From: "Alan R" <>
To: <>
Sent: Friday, May 16, 2008 9:49 AM
Subject: [DNA] age of U152/S28


> The discussion about the difference between the MRCA date and the date of
> the mutation is interesting. The distinction is clear but I am worried
> that the real date of the arrival of a clade like S28 is wrongly taken by
> many to mean how old S28 is. Its easy to see a scenario where daughtering
> out etc means that the MRCA can be much more recent than the mutution.
> MRCA is therefore the minuimum possible age of a mutation and this minumum
> may be wildly younger than the mutation date. In other words MRCA is what
> archaeologists call the 'terminus anti quem', the date before which
> something simply must have existed. However, if you dont have the reverse
> (terminus post-quem) then its use is limited. Can MRCAs be calculated for
> a sub-sub clade, a sub clade then the clade as a whole then the haplotype
> as a whole way to sort of 'squeeze' a mutation dating band? For example
> S28, all western R1b1c, all R1b1c, all R1b.
>
> Alan
>
> PS can the effect of daughtering out etc be computer simulated to allow a
> calibration of MRCA dates into mutation dates?
>
>
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