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Archiver > GENEALOGY-DNA > 2008-05 > 1210952943


From: Alan R <>
Subject: [DNA] age of U152/S28
Date: Fri, 16 May 2008 15:49:03 +0000 (GMT)


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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