Shuhua Xu et al., Genetic evidence supports linguistic affinity of Mlabri -- a hunter-gatherer group in Thailand. BMC Genetics, 2010. Open access.
The Mlabri are a group of nomadic hunter-gatherers inhabiting the rural highlands of Thailand. Little is known about the origins of the Mlabri and linguistic evidence suggests that the present-day Mlabri language most likely arose from Tin, a Khmuic language in Austro-Asiatic language family. This study aims to examine whether the genetic affinity of the Mlabri is consistent with this linguistic relationship, and to further explore the origins of this enigmatic population.
We conducted a genome-wide analysis of genetic variation using more than fifty thousand single nucleotide polymorphisms (SNPs) typed in thirteen population samples from Thailand, including the Mlabri, Htin and neighboring populations of the Northern Highlands, speaking Austro-Asiatic, Tai-Kadai and Hmong-Mien languages. The Mlabri population showed higher LD and lower haplotype diversity when compared with its neighboring populations. Both model-free and Bayesian model-based clustering analyses indicated a close genetic relationship between the Mlabri and the Htin, a group speaking a Tin language.
Our results strongly suggested that the Mlabri share more recent common ancestry with the Htin. We thus provided, to our knowledge, the first genetic evidence that supports the linguistic affinity of Mlabri, and this association between linguistic and genetic classifications could reflect the same past population processes.
While finding out about the Mlabri, an ethnicity I had never before heard of, and confirming that hunter-gatherers of Austroasiatic language do not just exist nowadays in Malaysia, is interesting in itself, what most has provoked my attention is the genetic comparison between various South East Asian ethnicities and the HapMap North Chinese and Japanese samples.
It seems that the paper has come right in time to illustrate the ongoing debate elsewhere on this blog, on whether there is any specific marker to Northern Han (or even Han in general) and other major East Asian populations such as Koreans and Japanese.
What I am realizing is that there is nothing really specific and that these northern populations almost invariably cluster with some of their southern neighbors, which are much more diverse. This really surprises me a bit because I would have expected that the Neolithic of the Yellow River, surely at the origin of the Chinese ethnicity (Han, Hui) would have been created by a somewhat distinct group that we should be able to identify by some genetic marker or set of markers, even if they spread southwards as the Chinese empire did.
Not at all. It seems that such specificity is almost invisible and that the Han (as well as genetically similar Korean and Japanese peoples) are very much unspecific in terms of genetic markers that could be easy to spot. They rather seem like melting pots of lineages which are traced to likely origins in the South of East Asia.
And, as I say this study comes very handy to illustrate this pattern within autosomal DNA as well, with Chinese and Japanese clustering with Hmong-Mien specially and then with Tai-Kadai peoples.
The neighbor-joining (NJ) tree:
The Htin and Mlabri are of course Austroasiatic, even if color-coded differently. JPT stands from Japanese from Tokyo and CHB as Chinese from Beijing (they are standard HapMap samples). The Karen are Tibeto-Burman speakers.
The maximum likelihood (ML) tree:
Careful here because the color-coding is not linguistic. As said before the Karen are Tibeto-Burman speakers and not Austroasiatic as would seem from their clustering and red color. CEU are Caucasoids of European ancestry from Utah and YRI are Yoruba from Nigeria (again standard HapMap samples for comparison). Cursive text is mine.
In this ML tree is maybe where the clustering is more apparent: the whole East Asia is first divided between the Mon and all the rest. They are neighbors of the Karen and linguistically most related to other Austroasiatics but they clearly cluster apart from all.
Then they branch into other Austroasiatics plus Karen (TB) and Tai-Kadai, Hmong-Mien and northern ethnicities. And this last group branches out into Tai (a branch of Tai-Kadai) and an amalgam of other Tai-Kadai (Yao), Hmong-Mien (Hmong) and the northern ethnicities. And only at this stage a North-South divide becomes apparent.