I would be interested in how people envisage the origin of the different paths they took.
As for the when, based on Michal's calculations, I think the following dates seem reasonable:
haplogroup R - c. 30000BC
haplogroup R1 - c. 25000BC
R1b-P25 - c. 20000BC
That would place R1 at the start of the LGM,not the end as previously suggested.
This map shows the conditions that the first R1 man may have faced
http://en.wikipedia.org/wiki/File:La...tation_map.png
Essentially, other than small refugia not noted on a map of this scale it can be seen there was essentially a choice of living either in southern areas of Europe and Asia or living along the steppe tundra belt that stretch across Eurasia.
Maciamo keeps making statements that this allowed free movement from Altai to the Atlantic but this is not the case. Communication between east and west was enormously impeded and squeezed by the northern ice sheets and polar deserts to the north and the Alpine glaciars to the south. This is borne out by the cultural differences that are marked the LGM with Solutrian developing in the west during a long period of isolation during the LGM (culture probably arose fairly early in the LGM.
So what are the options for R1 to have spread from somewhere like central Asia across Europe.
Clearly the Aurignacian c. 40000BC is not a good candidate as it is far too early for even R*. Prior to the LGM the Gravettian swept Europe a little c. 28000BC. Its origins and direction of spread are still debated. In itself it is a little younger than R* in Michal's calculations. It beat the LGM in its spread across Europe before east and west diverged through separation in the LGM. However, the problem with this is this movement apparently pre-dated the origin date of R1 meaning that if Gravettian crossed Europe with R involved it would have been R*, not R1 and you would have ended up with separated R* populations in the western and eastern refugia, not two separated R1* populations. By the age of R1* the LGM had split Europe into refugia and there was developing separation between the eastern and western European populations. I think its very likely R was on the eastern side of the divide until at least the end of the LGM.
Indeed I am not so sure that R was involved in the Gravettian. The Mal'ta boy was a very late member of the Siberian middle upper palaeolithic culture, a culture which apparently started c. 30000BC with a reoccupation of Siberia. It is not the same as the gravettian culture which started a little later, had a different distribution and different technology. Other than the Mal'ta boy c. 22000BC this culture seems to have declined after 25000BC when the LGM started - pretty well the same date as R1* emerged. The Mal'ra boy seems to have been from a rare family of this dwindling culture who remained during the LGM until its very worst.
IMO it seems likely that R1 emerged among distant cousins of the Mal'ta boy who left south-central Siberia c. 25000BC. However, as the above map of the LGM implies there options for movement were being cut off by the desert band through central Asia and IMO they either had to live on the steppe tundra or move into south Asia. The area in between was not an option. My feeling is that is would have been much more natural to head straight west along the steppe tundra which is essentially the environment they were used to. Depending on exact dates the option of moving to south Asia may not have existed c. 25000BC when R1* arose.
Although I wouldnt rule out a short move south to around Altai, there doesnt seem to be any really upsteam forms of R in that area and if I had to guess I would say they moved along the northernmost edge of central Asia (the southermost edge of the steppe-tundra) until they reached the Caspian. Once at the Caspian its shores and waters would have allowed movement from north to south that was not possible in desert central Asia. during the LGM. Ideally we would want to identify this move from south-central Siberia archaeologically. I am going to dig into this to see if there is any evidence. If not maybe the Altai refuge needs considered again - something interesting given south Altai's potential role in the origin of microblade groups during the LGM and their role in the spread of haplogroup Q to America after the LGM.
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Originally Posted by alan
