Thursday, October 23, 2014

Surprises from the 45,000 year old Siberian Ust'-Ishim: why is he not closer to Africans than East Asians are?

The genome of the 45,000 year old Siberian Ust'-Ishim published yesterday in Nature (see John Hawks blog) again repeated the same absurd pattern of no genetic continuity between local people living in different periods of time. The Ust'-Ishim genome is no more related to the 24,000 year old Siberian MA1 than to living East Asians. But this kind of surprises is getting boring for me to mention in this blog.  (John Hawks said this in his blog: "This is not an isolated case, it is another example of what we see throughout the world: Ancient people represented by DNA that seem to have very little to do with the people who live in the same areas today. We're not finding the ancestors of living populations so much as we are finding branches of populations we did not know existed.")

A new kind of surprise is the failure to do all necessary studies or to present all relevant studies. One expect that the Ust'-Ishim genome should be almost 2 fold less distant to living Africans than East Asians are because he had 45,000 years less time to accumulate distance as shown in Figure 1A. But the paper made no mention of this key expectation from the Out of Africa model. 

It also makes no sense for Ust'-Ishim to be an outlier to living East Asians on a PCA plot (Figure 2) since the distance between Ust'-Ishim and East Asians should be almost 2 fold less distant than between certain pair of East Asians, again because Ust'-Ishim had 45,000 years less time to accumulate mutations/distance (Figure 1A).

Our results with the 1000 genomes data showed that East Asians CHS and Europeans GBR are equidistant to Africans LWK or YRI in fast evolving SNPs representing genome average (Figure 1B). This of course has nothing to do with mutation rate and time but represents maximum genetic distance and natural selection. We are going to soon analyse the Ust'-Ishim genome in the same way and we fully expect Ust'-Ishim to be equidistant or more distant to Africans than East Asians are, which would be the same pattern as our first blog post here in 2007 had shown for the Neanderthals. Now such a result would be truly inconvenient for the Out of Africa model, which is probably why it was left out in the paper. 

Figure 1

Figure 2

No comments: