Evolutionary history of continental southeast Asians: "early train" hypothesis based on genetic analysis of mitochondrial and autosomal DNA data.

The population history of the indigenous populations in island Southeast Asia is generally accepted to have been shaped by two major migrations: the ancient "Out of Africa" migration ∼50,000 years before present (YBP) and the relatively recent "Out of Taiwan" expansion of Austronesian agriculturalists approximately 5,000 YBP. The Negritos are believed to have originated from the ancient migration, whereas the majority of island Southeast Asians are associated with the Austronesian expansion. We determined 86 mitochondrial DNA (mtDNA) complete genome sequences in four indigenous Malaysian populations, together with a reanalysis of published autosomal single-nucleotide polymorphism (SNP) data of Southeast Asians to test the plausibility and impact of those migration models. The three Austronesian groups (Bidayuh, Selatar, and Temuan) showed high frequencies of mtDNA haplogroups, which originated from the Asian mainland ∼30,000-10,000 YBP, but low frequencies of "Out of Taiwan" markers. Principal component analysis and phylogenetic analysis using autosomal SNP data indicate a dichotomy between continental and island Austronesian groups. We argue that both the mtDNA and autosomal data suggest an "Early Train" migration originating from Indochina or South China around the late-Pleistocene to early-Holocene period, which predates, but may not necessarily exclude, the Austronesian expansion.

Mapping human genetic diversity in Asia.

Asia harbors substantial cultural and linguistic diversity, but the geographic structure of genetic variation across the continent remains enigmatic. Here we report a large-scale survey of autosomal variation from a broad geographic sample of Asian human populations. Our results show that genetic ancestry is strongly correlated with linguistic affiliations as well as geography. Most populations show relatedness within ethnic/linguistic groups, despite prevalent gene flow among populations. More than 90% of East Asian (EA) haplotypes could be found in either Southeast Asian (SEA) or Central-South Asian (CSA) populations and show clinal structure with haplotype diversity decreasing from south to north. Furthermore, 50% of EA haplotypes were found in SEA only and 5% were found in CSA only, indicating that SEA was a major geographic source of EA populations.

An update of the general health status in the indigenous populations of Malaysia.

OBJECTIVES: Health scenarios are constantly evolving, particularly in developing countries but little is known regarding the health status of indigenous groups in Malaysia. This study aims to elucidate the current health status in four indigenous populations in the country, who by and large been left out of mainstream healthcare developments. METHODS: Participants were recruited from the Temuan, Jehai, Kensiu and Bidayuh indigenous groups throughout Peninsula Malaysia and Sarawak. Health parameters including body mass index (BMI), blood pressure, casual blood glucose and, total cholesterol levels were measured using established methods. Malondialdehyde (MDA) and ferric-reducing antioxidant power (FRAP) levels were measured to assess oxidative stress status. Blood films were screened for evidence of microbial or parasitic infections and leukocyte differential counting was performed. RESULTS: The Temuan and Bidayuh who are more urbanized, had significantly higher mean body weight, BMI, total cholesterol (p<0.05) and higher prevalence of obesity and hypercholesterolemia. Low cholesterol levels, elevated eosinophil counts and increased total IgE, indicative of immune responses to infection or allergy, were recorded in the rural Kensiu and Jehai. The Kensiu had higher levels of FRAP and lower levels of MDA, whereas the reverse was found in the Temuan. This suggests reduced oxidative stress in the Kensiu compared to the Temuan. Expected correlations between FRAP and MDA levels with age, were evident in Jehai. CONCLUSIONS: Our findings reflect a shifting health burden and an epidemiological transition, particularly in the Temuan and Bidayuh. These changes could be attributed to dietary habits, lifestyles and socio-economic factors brought about by urbanization.