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From: Alan R <>
Subject: Re: [DNA] TRMCA for R1b1
Date: Tue, 2 Dec 2008 21:22:20 +0000 (GMT)


Another approach to the origins of various clades is to look at where a particular one is found and ask yourself does the archaeology at any stage show a common thread that can explain the common genetic thread. In other words a commonality of genes could well be derived from the period when there was a commonality of archaeological culture. This also needs to take into account he possibility of a staged spread, i.e. one where the genes arrive in one place in one era with one archaeological culture but may not spread onto another area until a later era and in the guise of another archaeological culture.  This is rather more complex and I have to say a little knowledge can be a dangerous thing when doing this sort of exercise.  Even among professional archaeologists there are few who have a good enough up to date knowledge of all periods in all parts of Europe to be able to see the rough outline.

Anyway, the basic principle is that common genes in an area should mean common archaeology although we have to mindful of a staged spread with geographically intermediate cultures possibly having a role. This can be done for any genetic signal but we can try with M269 first.  I don't have time to go through all the scenarios for R1b and archaeology and to be honest its impossible to explain ALL of the spread of R1b in one archaeological horizon.  There were clearly at least a couple of stages involved.  For now though I would just say that its very very difficult to see an archaeological horizon or even a sequence of them that would take R1b to the full spread of its current locations from an Iberian refugia.  For a start, the normal candidate (indeed the only one that incontestably moved SW to north and east) is the Magdalenian.  Its in a sense the only single step candidate but it fails to provide a single step solution to the R1b
distribution.  The Magdallenain or derived cultures (Azilian etc) could explain R1b distribution in wstern and west-central Europe but did not extend into places like Italy or the east Mediterranean or into much of Scandinavia or eastern Europe or Asia.  Now that alone compels one to look for a possible second stage movements from the west into the south and east. 
 
Now, that is where the problem lies.  The overwhelming trend throughout the Neolithic was for cultures to move south-east/south/east to north/west/north-west (there is not even any point in discussing the beakers BTW.  No archaeologist worth their salt will say that its point of origin or direction of spread or even its nature is established beyond doubt)  I wont venture beyond the Neolithic for now as the Bronze Age is complex but I would note that there are many parts of R1b Europe where continental  intrusion is not at all indicated in this period and where it is it is not west to east that is indicated.  I think we do not have any evidence of west-east movements of any degree from the Magdalenian until the Iron Age when the west-central European Celts partly headed that way.  Even in the Dark Ages the movement was largely east-west or north-south.  So, basically the only scenario that would fit a western origin and eastwards direction
of spread for R1b is  a dual one whereby the old ice age refugia and its immediate post-LGM Magdalenian outpourings explains the R1b in western Europe north of the Alps while the R1b of eastern and southern Europe (other than the Mediterranean coast of Spain and France) and Asia is down to Iron Age Celtic and Germanic and even later expansions.  There is no other possible explanation in the archaeological and historical record for R1b distribution that fits the western refugia scenario and I have heard versions of this many times here.
 
However, I will ask one simple question.  Does the genetic data so far support this scenario?  Do we see the oldest R1b in Iberia/S.France, then R1b that is perhaps only two-thirds to half as old in the rest of NW/west-central Europe then R1b that is only about a tenth of the age of that in Iberia in places like Italy, the eastern Mediterranean, Anatolia, SW Asia etc. I think the answer seems (and I rely on others for this) to be that this is close to the opposite of what has been found when dating techniques and even the very form of the R1b is examined and compared across Eurasia. 
 
Alan       

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