I can't reply to any specific comments at the moment since I've been travelling all week, but I did read the nature article and here's a few thoughts...
1) It does seem to confirm that the Ydna belongs to R*, but doesn't seem to offer any details which I hope will come out soon
2) I agree with the authors opinion (and Maciamo's above) that the common autosomal component in Amerindians and West Asians is due P-M45 (R* and Q*) commonality (seems obvious)
The level of content was appropriate for Nature, however here's some things I still want to know.
1) What is the Denisovian admixture of the subjects? If the boy has Mongoloid features and no East Asian admixture, then what about Denisovian? I am curious if certain Mongoloid features, such as the pronounced zygomatic bone, are in fact Denisovian in the same way that certain Caucasian features may be relicts of Neanderthals. In the case of Caucasians, the account of almost all of the distinct Caucasian skeletal features could be reduced to Neanderthal admixture.
It possible that features associated with the modern Mongoloid taxon are in fact a composite of several races, one of which contributed relict Denisovian traits of sapiens in the Altai.
In other words, Neoteny, for example, may have come from the autosomally distinct 'East Asians', whereas other traits, like the high zygomatic process may have been introduced by another population.
It would be interesting to know since modern sapiens with the most Denisovian ancestry are those within the eastern MNOPS tree. The Mal'ta and Afontova finds are also in the Denisova region where I might expect to find admixture. Since we don't have Denisova skulls to examine, we may be able to further triangulate to imagine their appearance through these finds.
Dienekes's Blog had an interesting article on January 21, 2013 about the Denisovian admixture in a 40,000 year old skeleton from China. I don't really know how this ties in with the 24,000 year old find in Siberia, but the article suggests that the Denisovian percentage in Asians has been constant for a very long time, and that the 40,000 year old is related to Asians and Native Americans but not Europeans.
"Another new PNAS paper that hasn't yet appeared in the journal website. Still, from this description at ScienceNews this appears to be Very Important, as it pertains to a 40,000-year-old modern human, which, if I'm not mistaken is the oldest modern human tested so far:
Ancient DNA from cell nuclei and maternally inherited mitochondria indicates that this individual belonged to a population that eventually gave rise to many present-day Asians and Native Americans, says a team led by Qiaomei Fu and Svante Paabo, evolutionary geneticists at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
The partial skeleton, unearthed in Tianyuan Cave near Beijing in 2003, carries roughly the same small proportions of Neandertal and Denisovan genes as living Asians do (SN: 8/25/12, p. 22), the scientists report online January 21 in the Proceedings of the National Academy of Sciences.
The Max Planck press release adds some
information:
The genetic profile reveals that this early modern human was related to the ancestors of many present-day Asians and Native Americans but had already diverged genetically from the ancestors of present-day Europeans.
This is an important finding because some published demographic models had Europeans and East Eurasians diverging as recently as ~20 thousand years ago. It now appears that they did so already at around the time of the Upper Paleolithic revolution, when unambiguous evidence of modern humans across Eurasia exists.
UPDATE I: While we wait for this paper to appear on the
PNAS website, it might be useful to wonder whether the Tianyuan sample might fall on the East Asian/Amerindian group or the more general "Ancestral South Indian" (ASI)/East Eurasian group.
According to
current dating, haplogroup M itself is ~50 thousand years old, and most of the subclades therein coalesce to younger than 40ky times. It's possible that the Tianyuan sample dates from a period where ASI/East Asian differentiation had only just begun or was just about to begin.
The press release makes clear that Tianyuan was already "Asian" rather than generalized Eurasian, proving that East/West Eurasian differentiation had begun by ~40kya. It will be interesting to see whether it can be placed on a more specific "East Eurasian" group rather than a generalized "Asian" one."
