Genetic scientists from China have discovered a small portion of Neanderthal genome (18 genes on chromosome 3, with several related to UV-light adaptation) in up to 66 percent of modern East Asian population.

Their study, published in the journal Molecular Biology and Evolution, shows that this portion (including Hyal2, a gene related to the cellular response to ultraviolet-B irradiation) was positively selected and enriched in East Asians, ranging from up to 49.4 percent in Japanese to 66.5 percent in Southern Chinese.

“Interestingly, the geographic distribution of the Neanderthal genomic region suggests that UV-light mutations were shown to be lost during the exodus of modern human from Africa, and reintroduced to Eurasians from Neanderthals,” said study senior author Dr Li Jin from both Fudan University in Shanghai and the Shanghai Institute for Biological Sciences.

“Overall, it is still very controversial whether there are more Neanderthal DNA contributions to Asians than Europeans, as we have evidence to argue against this.”

“Although in the case of the Hyal2 variant, it did indeed have a higher frequency in Asians.”

From 45,000 years to 5,000 years before present, effective population sizes of the Neanderthal region increased at a steady rate.

Notably, the growth rate of the effective population size increased at around 5,000 to 3,500 years before present, which suggests a population expansion event.

This Asian-specific Neanderthal evolutionary event is also consistent with previous reports of higher levels of Neanderthal ancestry in East Asians than in Europeans.

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Qiliang Ding et al. Neanderthal Introgression at Chromosome 3p21.31 was Under Positive Natural Selection in East Asians. Molecular Biology and Evolution, published online December 13, 2013; doi: 10.1093/molbev/mst260