Monday, July 14, 2008

Genetic history in mainland SE Asia as revealed by ancient and modern mtDNA

A new American Journal of Physical Anthropology article studies the mtDNA from both ancient human remains in northeast Thailand, and modern human samples from the same area and surrounding regions.

The findings basically show that the two ancient groups, from the Bronze and Iron ages, resemble Austro-Asiatic-speaking populations. The modern Tai-Kadai speakers were more closely related to Southeast Asians than to East Asians, but they formed a separate group in the region. Among Southeast Asians the Tai-Kadai of Thailand are closest to the Khmer and this is explained by the researchers as related to the Khmer subjugation of the Tai-Kadai after their arrival in Thailand in the 10th-11th CE.

American Journal of Physical Anthropology

Published Online: 9 Jul 2008

Genetic history of Southeast Asian populations as revealed by ancient and modern human mitochondrial DNA analysis

Patcharee Lertrit, Samerchai Poolsuwan, Rachanie Thosarat, Thitima Sanpachudayan, Hathaichanoke Boonyarit, Chatchai Chinpaisal, Bhoom Suktitipat

The 360 base-pair fragment in HVS-1 of the mitochondrial genome were determined from ancient human remains excavated at Noen U-loke and Ban Lum-Khao, two Bronze and Iron Age archaeological sites in Northeastern Thailand, radio-carbon dated to circa 3,500-1,500 years BP and 3,200-2,400 years BP, respectively. These two neighboring populations were parts of early agricultural communities prevailing in northeastern Thailand from the fourth millennium BP onwards. The nucleotide sequences of these ancient samples were compared with the sequences of modern samples from various ethnic populations of East and Southeast Asia, encompassing four major linguistic affiliations (Altaic, Sino-Tibetan, Tai-Kadai, and Austroasiatic), to investigate the genetic relationships and history among them. The two ancient samples were most closely related to each other, and next most closely related to the Chao-Bon, an Austroasiatic-speaking group living near the archaeological sites, suggesting that the genetic continuum may have persisted since prehistoric times in situ among the native, perhaps Austroasiatic-speaking population. Tai-Kadai groups formed close affinities among themselves, with a tendency to be more closely related to other Southeast Asian populations than to populations from further north. The Tai-Kadai groups were relatively distant from all groups that have presumably been in Southeast Asia for longer-that is, the two ancient groups and the Austroasiatic-speaking groups, with the exception of the Khmer group. This finding is compatible with the known history of the Thais: their late arrival in Southeast Asia from southern China after the 10th-11th century AD, followed by a period of subjugation under the Khmers. Am J Phys Anthropol, 2008. © 2008 Wiley-Liss, Inc.

Paul Kekai Manansala