This Wall et al. paper is the third study in a row on Neanderthal ancestry in modern humans in which East Asians clearly top the list as the most Neanderthal-admixed group. The reasons for this aren't yet clear. The study also picked up low level Neanderthal influence in the Maasai of Kenya, which was most likely the result of significant and relatively recent admixture from Eurasia into these Africans (estimated at around 30% in each Maasai genome).
By using the high coverage Denisova genome, we are able to show that the admixture rate into East Asians is 40% higher than into Europeans. We conclude that admixture between Neanderthals and modern humans did not occur at a single time and place, as suggested by GREEN et al. (2010). Some of it had to have occurred after the separation of East Asians and Europeans. Further, we show that there was significant Neanderthal admixture into the Maasai population of East Africa, probably because of secondary contact with a non-African population rather than admixture directly from Neanderthals.
Our new method for identifying introgressed Neanderthal fragments in human populations detected 226 different putative Neanderthal regions. The relative frequencies of these putative Neanderthal haplotypes in the 42 sampled modern human individuals then provide estimates of the relative contributions of Neanderthal DNA to the gene pools of contemporary human populations. We found that on average the ‘Neanderthal haplotypes’ were at higher frequency in the East Asians than in the Europeans (9.6% vs. 6.4%; p = 3.0 x 10-4, permutation test), consistent with the D-statistic results presented in Figure 3. We also found evidence for a small, but statistically significant, Neanderthal contribution to the genomes of the Maasai (p = 4.9 * 10-4), but did not find a significant difference in Neanderthal haplotype frequency between the East and South Asian samples (p >0.05).
Jeffrey D. Wall et al., Higher levels of Neanderthal ancestry in East Asians than in Europeans, Genetics: Early Online, published on February 14, 2013 as 10.1534/genetics.112.148213
Oetzi more Neandertal than modern Europeans because his ancestors came from...North Africa?