Upon the recent discoveries of Neanderthal and other archaic admixture in modern humans, it arose in the debates occasionally this almost forgotten matter of an X-linked haplotype that looked very much non-African. However Africa had only been sampled poorly back in that time and we lacked any confirmation on this haplotype being present or not in the Neanderthal genetic pool.
According to a new paper this X-DNA haplotype, known as B006, fits well with Neanderthal genetic data and is therefore a likely case of Neanderthal lineage among us.
Vania Yotova et al., An X-linked haplotype of Neandertal origin is present among all non-African populations. Molecular Biology and Evolution, 2011.
|Frequency of B006 worldwide|
It was previously known that the lineage was most common among Europeans and Native Americans, though maybe most diverse in Central-NE Asia. Almost nothing was known then about its presence among South Asians or Australian Aborigines and the little knowledge of the African scatter (mostly among Burkinabe peoples, with one Ethiopian individual as well) has been confirmed, it seems.
But most importantly B006 shares both mutations divergent from the ancestral (Chimpanzee) form among all those analyzed in the Neanderthal genome. One is common to most modern human lineages but the other transition is unique to B006 and the Neanderthal lineage:
In the available Neandertal sequence (Green et al. 2010), there is information on 20 out of 35 dys44 polymorphic sites. These represent eighteen ancestral and two derived alleles, fully matching the corresponding sites of B006 (Table 1). One of the derived alleles, C of rs6631517, is also shared with other dys44 haplotypes, whereas the second one, G of rs11795471, is unique to B006 (the information on two remaining B006-polymorphisms is not available).
While not yet fully demonstrated (further B006 haplotypes should be considered along further Neanderthal ones as well), the idea, until now purely speculative, of this lineage being a Neanderthal one, clearly gains strength with this paper's work.