Reconstructing the human genetic history of mainland Southeast Asia: Insights from genome-wide data from Thailand and Laos

Thailand and Laos, located in the center of Mainland Southeast Asia (MSEA), harbor diverse ethnolinguistic groups encompassing all five language families of MSEA: Tai-Kadai (TK), Austroasiatic (AA), Sino-Tibetan (ST), Hmong-Mien (HM), and Austronesian (AN). Previous genetic studies of Thai/Lao populations have focused almost exclusively on uniparental markers and there is a paucity of genome-wide studies. We therefore generated genome-wide SNP data for 33 ethnolinguistic groups, belonging to the five MSEA language families from Thailand and Laos, and analyzed these together with data from modern Asian populations and SEA ancient samples. Overall, we find genetic structure according to language family, albeit with heterogeneity in the AA-, HM-, and ST-speaking groups, and in the hill tribes, that reflects both population interactions and genetic drift. For the TK speaking groups, we find localized genetic structure that is driven by different levels of interaction with other groups in the same geographic region. Several Thai groups exhibit admixture from South Asia, which we date to ∼600–1000 years ago, corresponding to a time of intensive international trade networks that had a major cultural impact on Thailand. An AN group from Southern Thailand shows both South Asian admixture as well as overall affinities with AA-speaking groups in the region, suggesting an impact of cultural diffusion. Overall, we provide the first detailed insights into the genetic profiles of Thai/Lao ethnolinguistic groups, which should be helpful for reconstructing human genetic history in MSEA and selecting populations for participation in ongoing whole genome sequence and biomedical studies

Re-evaluating Pleistocene-Holocene occupation of cave sites in north-west Thailand: New radiocarbon and luminescence dating

Established chronologies indicate a long-term 'Hoabinhian' hunter-gatherer occupation of Mainland Southeast Asia during the Terminal Pleistocene to Mid-Holocene (45 000-3000 years ago). Here, the authors re-examine the 'Hoabinhian' sequence from north-west Thailand using new radiocarbon and luminescence data from Spirit Cave, Steep Cliff Cave and Banyan Valley Cave. The results indicate that hunter-gatherers exploited this ecologically diverse region throughout the Terminal Pleistocene and the Pleistocene-Holocene transition, and into the period during which agricultural lifeways emerged in the Holocene. Hunter-gatherers did not abandon this highland region of Thailand during periods of environmental and socioeconomic change

Tropical limestone forest resilience during MIS-2: implications for Pleistocene foraging & modern conservation

In this paper we present a multi-proxy study of tropical limestone forest and its utilization by human groups during the major climatic and environmental upheavals of MIS-2 (29-11.7 ka BP). Our data are drawn from new field research within the Tràng An World Heritage property, on the edge of the Red River Delta, northern Vietnam. Key findings from this study include 1) that limestone forest formations were resilient to the large-scale landscape transformation and inundation of the Sunda continent at the end of the last glaciation; 2) that prehistoric human groups were probably present in this habitat through-out MIS-2; and 3) that the forested, almost insular, karst of Tràng An provided foragers with a stable resource-base in a wider changing landscape. These results have implications for our understanding of the prehistoric utilization of karst environments and resonance for conservation efforts in the face of climate and environmental change today

Characterization and radiocarbon dating of archaeological resins from southeast Asia.

NoFirst presented at an August 2001 national meeting of the American Chemical Society, material in this book provides a cross-section of current research in the area of chemistry applied to archaeological questions. Examples are given of the use of analytical methods in the study of a variety of archaeological materials, and inferences that can be made based on data patterns are discussed. Emphasis is on nondestructive testing and new developments in determining an object's age and composition

Cultural variation impacts paternal and maternal genetic lineages of the Hmong-Mien and Sino-Tibetan groups from Thailand

The Hmong-Mien (HM) and Sino-Tibetan (ST) speaking groups are known as hill tribes in Thailand; they were the subject of the first studies to show an impact of patrilocality vs. matrilocality on patterns of mitochondrial (mt) DNA vs. male-specific portion of the Y chromosome (MSY) variation. However, HM and ST groups have not been studied in as much detail as other Thai groups; here we report and analyze 234 partial MSY sequences (∼2.3 mB) and 416 complete mtDNA sequences from 14 populations that, when combined with our previous published data, provides the largest dataset yet for the hill tribes. We find a striking difference between Hmong and IuMien (Mien-speaking) groups: the Hmong are genetically different from both the IuMien and all other Thai groups, whereas the IuMien are genetically more similar to other linguistic groups than to the Hmong. In general, we find less of an impact of patrilocality vs. matrilocality on patterns of mtDNA vs. MSY variation than previous studies. However, there is a dramatic difference in the frequency of MSY and mtDNA lineages of Northeast Asian (NEA) origin vs. Southeast Asian (SEA) origin in HM vs. ST groups: HM groups have high frequencies of NEA MSY lineages but lower frequencies of NEA mtDNA lineages, while ST groups show the opposite. A potential explanation is that the ancestors of Thai HM groups were patrilocal, while the ancestors of Thai ST groups were matrilocal. Overall, these results attest to the impact of cultural practices on patterns of mtDNA vs. MSY variation

Analysis of the Preserved Amino Acid Bias in Peptide Profiles of Iron Age Teeth from a Tropical Environment Enable Sexing of Individuals Using Amelogenin MRM

The first dental proteomic profile of Iron Age individuals (ca. 2000–1000 years B.P.), collected from the site of Long Long Rak rock shelter in northwest Thailand is described. A bias toward the preservation of the positively charged aromatic, and polar amino acids is observed. It is evident that the 212 proteins identified (2 peptide, FDR <1%) comprise a palimpsest of alterations that occurred both ante-mortem and post-mortem. Conservation of amino acids within the taphonomically resistant crystalline matrix enabled the identification of both X and Y chromosome linked amelogenin peptides. A novel multiple reaction monitoring method using the sex specific amelogenin protein isoforms is described and indicate the teeth are of male origin. Functional analysis shows an enrichment of pathways associated with metabolic disorders and shows a capacity for harboring these conditions prior to death. Stable isotope analysis using carbon isotopes highlights the strongly C 3 based (≈80%) diet of the Long Long Rak cemetery people, which probably comprised rice combined with protein from freshwater fish among other food items. The combination of proteomics and stable isotope analysis provides a complementary strategy for assessing the demography, diet, lifestyle, and possible diseases experienced by ancient populations