Tuesday, March 26, 2013

More Trouble for the Complete "Out-of-Africa" Model

Science Daily is reporting on research done on migration patterns involving early anatomically modern humans.  They write:
The team, led by Johannes Krause from Tübingen University, was able to reconstruct more than ten mitochondrial genomes (mtDNAs) from modern humans from Eurasia that span 40,000 years of prehistory. The samples include some of the oldest modern human fossils from Europe such as the triple burial from Dolni Vestonice in the Czech Republic, as well as the oldest modern human skeletons found in Germany from the site of Oberkassel close to Bonn.

The researchers show that pre-ice age hunter-gatherers from Europe carry mtDNA that is related to that seen in post-ice age modern humans such as the Oberkassel fossils. This suggests that there was population continuity throughout the last major glaciation event in Europe around 20,000 years ago. Two of the Dolni Vestonice hunter-gatherers also carry identical mtDNAs, suggesting a close maternal relationship among these individuals who were buried together.
It was also suggested that the split between non-Africans and Africans was much later in time, between 62 and 95 ky BP. This would mean that the window of hybridization would be much larger than originally thought and that archaic and modern hybridization was a good deal more common until a later time than thought.  The first moderns that we have are from the site of Bouri, in the Afar Triangle, and date to around 160 ky BP.  Maddeningly, what we are lacking is good material between that time and around 100 ky BP, when the Near Eastern Skhul and Qafzeh material are found.  A friend of mine and I argued that the archaic traits in those skulls represent African archaic traits and not hybridization with Neandertals.  This would seem to support that.  They suggest that there are discrepancies between these results and previous ones but, critically, that these results tend to support both the palaeoanthropological and archaeological evidence.    Here is the citation:

Fu et al., A Revised Timescale for Human Evolution Based on Ancient Mitochondrial Genomes,
Current Biology (2013), http://dx.doi.org/10.1016/j.cub.2013.02.044

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