June 15, 2011

Tai and Mon-Khmer of northern Thailand

BMC Genetics 2011, 12:56doi:10.1186/1471-2156-12-56

Genetic structure of the Mon-Khmer speaking groups and their affinity to the neighbouring Tai populations in Northern Thailand

Wibhu Kutanan et al.

The Mon-Khmer speaking peoples inhabited northern Thailand before the arrival of the Tai speaking people from southern China in the thirteenth century A.D. Historical and anthropological evidence suggests a close relationship between the Mon-Khmer groups and the present day majority northern Thai groups. In this study, mitochondrial and Y-chromosomal DNA polymorphisms in more than 800 volunteers from eight Mon-Khmer and ten Tai speaking populations were investigated to estimate the degree of genetic divergence between these major linguistic groups and their internal structure.

A large fraction of genetic variation is observed within populations (about 80% and 90 % for mtDNA and the Y-chromosome, respectively). The genetic divergence between populations is much higher in Mon-Khmer than in Tai speaking groups, especially at the paternally inherited markers. The two major linguistic groups are genetically distinct, but only for a marginal fraction (1 to 2 %) of the total genetic variation. Genetic distances between populations correlate with their linguistic differences, whereas the geographic distance does not explain the genetic divergence pattern.

The Mon-Khmer speaking populations in northern Thailand exhibited the genetic divergence among each other and also when compared to Tai speaking peoples. The different drift effects and the post-marital residence patterns between the two linguistic groups are the explanation for a small but significant fraction of the genetic variation pattern within and between them.


1 comment:

Andrew Oh-Willeke said...

The paper is not very clear and has serious losing sight of the forest for the trees issues. Both Mon Khmer and Tai samples have lots of hgs, but the paper never mentions, so far as I can tell, what they are or how closely related phylogenetically to each other.

The bottom line conclusion seems to be the there are many diverse clusters of Mon-Khmer, with each little grouping unlike the other in a directions of variation from a central cluster of Northern Tai people. It hypothesizes Mon-Khmer admixture into Tai (while the absence of the reverse) but has almost no hg overlap between Mon-Khmer and Tai.

One of the more memorable points in the paper is its recognition of the fact that the Mon-Khmer were routed by the Tai as recently as the 13th century, reminding us of how relevant even very recent historical events can be to current population genetics in a given place.