Mitochondrial DNA variation in Nicobarese Islanders.

The aboriginal populations living in the Nicobar Islands are hypothesized to be descendants of people who were part of early human dispersals into Southeast Asia. However, analyses of ethnographic histories, languages, morphometric data, and protein polymorphisms have not yet resolved which worldwide populations are most closely related to the Nicobarese. Thus, to explore the origins and affinities of the Nicobar Islanders, we analyzed mitochondrial DNA (mtDNA) hypervariable region 1 sequence data from 33 Nicobarese Islanders and compared their mtDNA haplotypes to those of neighboring East Asians, mainland and island Southeast Asians, Indians, Australian aborigines, Pacific Islanders, and Africans. Unique Nicobarese mtDNA haplotypes, including five Nicobarese mtDNA haplotypes linked to the COII/tRNA(Lys) 9-bp deletion, are most closely related to mtDNA haplotypes from mainland Southeast Asian Mon-Kmer-speaking populations (e.g., Cambodians). Thus, the dispersal of southern Chinese into mainland Southeast Asia may have included a westward expansion and colonization of the islands of the Andaman Sea.     

Phylogenetic distinctiveness of Middle Eastern and Southeast Asian village dog Y chromosomes illuminates dog origins

Modern genetic samples are commonly used to trace dog origins, which entails untested assumptions that village dogs reflect indigenous ancestry or that breed origins can be reliably traced to particular regions. We used high-resolution Y chromosome markers (SNP and STR) and mitochondrial DNA to analyze 495 village dogs/dingoes from the Middle East and Southeast Asia, along with 138 dogs from >35 modern breeds to 1) assess genetic divergence between Middle Eastern and Southeast Asian village dogs and their phylogenetic affinities to Australian dingoes and gray wolves (Canis lupus) and 2) compare the genetic affinities of modern breeds to regional indigenous village dog populations. The Y chromosome markers indicated that village dogs in the two regions corresponded to reciprocally monophyletic clades, reflecting several to many thousand years divergence, predating the Neolithic ages, and indicating long-indigenous roots to those regions. As expected, breeds of the Middle East and East Asia clustered within the respective regional village dog clade. Australian dingoes also clustered in the Southeast Asian clade. However, the European and American breeds clustered almost entirely within the Southeast Asian clade, even sharing many haplotypes, suggesting a substantial and recent influence of East Asian dogs in the creation of European breeds. Comparison to 818 published breed dog Y STR haplotypes confirmed this conclusion and indicated that some African breeds reflect another distinct patrilineal origin. The lower-resolution mtDNA marker consistently supported Y-chromosome results. Both marker types confirmed previous findings of higher genetic diversity in dogs from Southeast Asia than the Middle East. Our findings demonstrate the importance of village dogs as windows into the past and provide a reference against which ancient DNA can be used to further elucidate origins and spread of the domestic dog.     

Molecular diversity and phylogeography of the Asian leopard cat, Felis bengalensis, inferred from mitochondrial and Y-chromosomal DNA sequences

To investigate genetic diversity and phylogeography of the Asian leopard cat (Felis bengalensis), mitochondrial DNA (mtDNA) sequences were determined for 39 individuals from various areas. Sequences combining the complete cytochrome b gene (1,140 bp) with the partial control region (646-810 bp) were classified into 24 haplotypes: 21 types from 21 animals, one from eight animals from Tsushima Islands, one from eight animals from Iriomote Island, and one from two animals from Southeast Asia. Phylogenetic trees of the 24 haplotypes clearly showed three clades: a Northern Lineage and Southern Lineages 1 and 2. The Northern Lineage consisted of animals from Tsushima Islands, the Korean Peninsula, the continental Far East, Taiwan, and Iriomote Island. Within the Northern Lineage, genetic contacts could have occurred between geographically neighboring populations before isolation by straits. Southern Lineage 1, comprising Southeast Asian animals, showed higher genetic diversity. Southern Lineage 2 had large genetic distances from other lineages. Within the control region, the Asian leopard cats shared two to four repetitive motifs, and the number of motifs and their constitution were highly variable among individuals. The motifs were polymorphic even within individuals and could be classified into 31 types. Finally, males of mtDNA Southern Lineage 1 had either of two types of the Y-chromosomal gene ZFY, whereas all males of Northern Lineage shared only one type. Our results indicate that the diversity of southern populations is higher and that genetic differentiation among northern local populations reflects past geographical isolation.     

The genetic origins of the Andaman Islanders

Mitochondrial sequences were retrieved from museum specimens of the enigmatic Andaman Islanders to analyze their evolutionary history. D-loop and protein-coding data reveal that phenotypic similarities with African pygmoid groups are convergent. Genetic and epigenetic data are interpreted as favoring the long-term isolation of the Andamanese, extensive population substructure, and/or two temporally distinct settlements. An early colonization featured populations bearing mtDNA lineage M2, and this lineage is hypothesized to represent the phylogenetic signal of an early southern movement of humans through Asia. The results demonstrate that Victorian anthropological collections can be used to study extinct, or seriously admixed populations, to provide new data about early human origins.     

Genetic studies of human diversity in East Asia

East Asia is one of the most important regions for studying evolution and genetic diversity of human populations. Recognizing the relevance of characterizing the genetic diversity and structure of East Asian populations for understanding their genetic history and designing and interpreting genetic studies of human diseases, in recent years researchers in China have made substantial efforts to collect samples and generate data especially for markers on Y chromosomes and mtDNA. The hallmark of these efforts is the discovery and confirmation of consistent distinction between northern and southern East Asian populations at genetic markers across the genome. With the confirmation of an African origin for East Asian populations and the observation of a dominating impact of the gene flow entering East Asia from the south in early human settlement, interpretation of the north-south division in this context poses the challenge to the field. Other areas of interest that have been studied include the gene flow between East Asia and its neighbouring regions (i.e. Central Asia, the Sub-continent, America and the Pacific Islands), the origin of Sino-Tibetan populations and expansion of the Chinese.     

Y-chromosome and mitochondrial DNA studies on the population structure of the Christmas Island community

Christmas Island is a remote Australian territory located close to the main Indonesian island of Java. Y-chromosome and mitochondrial DNA (mtDNA) markers were used to investigate the genetic structure of the population, which comprises communities of mixed ethnic origin. Analysis of 12 Y-chromosome biallelic polymorphisms revealed a high level of gene diversity and haplotype frequencies that were consistent with source populations in southern China and Southeast Asia. mtDNA hypervariable segment I (HVS-I) sequences displayed high levels of haplotype diversity and nucleotide diversity that were comparable to various Asian populations. Genetic distances revealed extremely low mtDNA differentiation among Christmas Islanders and Asian populations. This was supported by the relatively high proportion of sequence types shared among these populations. The most common mtDNA haplogroups were M* and B, followed by D and F, which are prevalent in East/Southeast Asia. Christmas Islanders of European descent were characterized by the Eurasian haplogroup R*, and a limited degree of admixture was observed. In general, analysis of the genetic data indicated population affinities to southern Chinese (in particular from the Yunnan Province) and Southeast Asia (Thailand, Malaysia, and Cambodia), which was consistent with historical records of settlement. The combined use of these different marker systems provides a useful and appropriate model for the study of contemporary populations derived from different ethnic origins.     

The northeast Indian passageway: a barrier or corridor for human migrations?

The northeast Indian passageway connecting the Indian subcontinent to East/Southeast Asia is thought to have been a major corridor for human migrations. Because it is also an important linguistic contact zone, it is predicted that northeast India has witnessed extensive population interactions, thus, leading to high genetic diversity within groups and heterogeneity among groups. To test this prediction, we analyzed 14 biallelic and five short tandem-repeat Y-chromosome markers and hypervariable region 1 mtDNA sequence variation in 192 northeast Indians. We find that both northeast Indian Y chromosomes and mtDNAs consistently show strikingly high homogeneity among groups and strong affinities to East Asian groups. We detect virtually no Y-chromosome and mtDNA admixture between northeast and other Indian groups. Northeast Indian groups are also characterized by a greatly reduced Y-chromosome diversity, which contrasts with extensive mtDNA diversity. This is best explained by a male founder effect during the colonization of northeast India that is estimated to have occurred within the past 4,000 years. Thus, contrary to the prediction, these results provide strong evidence for a genetic discontinuity between northeast Indian groups and other Indian groups. We, therefore, conclude that the northeast Indian passage way acted as a geographic barrier rather than as a corridor for human migrations between the Indian subcontinent and East/Southeast Asia, at least within the past millennia and possibly for several tens of thousand years, as suggested by the overall distinctiveness of the Indian and East Asian Y chromosome and mtDNA gene pools.     

Independent maternal origin of Chinese swamp buffalo (Bubalus bubalis)

To obtain more knowledge on the origin and genetic diversity of the swamp buffalo (Bubalus bubalis) in China, the complete mitochondrial D-loop sequences of 119 samples representing seven native types were compared. Two mitochondrial DNA (mtDNA) lineages (lineages A and B) were determined for the Chinese swamp buffalo. Examination of the diversity patterns suggest that lineage A has undergone a population expansion event. Divergence of lineages A and B was estimated at 18,000 years ago. Combined analyses of mtDNA sequences from Chinese, Indian, Brazilian/Italian and Southeast Asian/Australian buffalo samples showed independent domestication events in the swamp buffalo from China and the river buffalo from the India subcontinent. The spread of swamp and river buffalo from China and India respectively to mainland Southeast Asia suggests that Southeast Asia is a hybrid zone for buffalo. Our data support the hypothesis of the evolution of domesticated swamp and river buffalo from ancestral swamp-like animals. These ancestral animals were extensively distributed across mainland Asia and most likely are represented today by the wild Asian buffalo (Bubalus arnee).     

Dental perspectives on the population history of Southeast Asia

This article uses metric and nonmetric dental data to test the "two-layer" or immigration hypothesis whereby Southeast Asia was initially occupied by an "Australo-Melanesian" population that later underwent substantial genetic admixture with East Asian immigrants associated with the spread of agriculture from the Neolithic period onwards. We examined teeth from 4,002 individuals comprising 42 prehistoric and historic samples from East Asia, Southeast Asia, Australia, and Melanesia. For the odontometric analysis, dental size proportions were compared using factor analysis and Q-mode correlation coefficients, and overall tooth size was also compared between population samples. Nonmetric population affinities were estimated by Smith's distances, using the frequencies of 16 tooth traits. The results of both the metric and nonmetric analyses demonstrate close affinities between recent Australo-Melanesian samples and samples representing early Southeast Asia, such as the Early to Middle Holocene series from Vietnam, Malaysia, and Flores. In contrast, the dental characteristics of most modern Southeast Asians exhibit a mixture of traits associated with East Asians and Australo-Melanesians, suggesting that these populations were genetically influenced by immigrants from East Asia. East Asian metric and/or nonmetric traits are also found in some prehistoric samples from Southeast Asia such as Ban Kao (Thailand), implying that immigration probably began in the early Neolithic. Much clearer influence of East Asian immigration was found in Early Metal Age Vietnamese and Sulawesi samples. Although the results of this study are consistent with the immigration hypothesis, analysis of additional Neolithic samples is needed to determine the exact timing of population dispersals into Southeast Asia.     

Austro-Asiatic tribes of Northeast India provide hitherto missing genetic link between South and Southeast Asia

Northeast India, the only region which currently forms a land bridge between the Indian subcontinent and Southeast Asia, has been proposed as an important corridor for the initial peopling of East Asia. Given that the Austro-Asiatic linguistic family is considered to be the oldest and spoken by certain tribes in India, Northeast India and entire Southeast Asia, we expect that populations of this family from Northeast India should provide the signatures of genetic link between Indian and Southeast Asian populations. In order to test this hypothesis, we analyzed mtDNA and Y-Chromosome SNP and STR data of the eight groups of the Austro-Asiatic Khasi from Northeast India and the neighboring Garo and compared with that of other relevant Asian populations. The results suggest that the Austro-Asiatic Khasi tribes of Northeast India represent a genetic continuity between the populations of South and Southeast Asia, thereby advocating that northeast India could have been a major corridor for the movement of populations from India to East/Southeast Asia.     

Approximate Bayesian analysis of Drosophila melanogaster polymorphism data reveals a recent colonization of Southeast Asia

Southeast Asian populations of the fruit fly Drosophila melanogaster differ from ancestral African and derived European populations by several morphological characteristics. It has been argued that this morphological differentiation could be the result of an early colonization of Southeast Asia that predated the migration of D. melanogaster to Europe after the last glacial period (around 10,000 years ago). To investigate the colonization process of Southeast Asia, we collected nucleotide polymorphism data for more than 200 X-linked fragments and 50 autosomal loci from a population of Malaysia. We analyzed this new single nucleotide polymorphism data set jointly with already existing data from an African and a European population by employing an Approximate Bayesian Computation approach. By contrasting different demographic models of these three populations, we do not find any evidence for an early divergence between the African and the Asian populations. Rather, we show that Asian and European populations of D. melanogaster share a non-African most recent common ancestor that existed about 2,500 years ago.     

Population prehistory of East Asia and the pacific as viewed from craniofacial morphology: The basic populations in East Asia,VII

Distance analyses were applied to 11 craniofacial measurements recorded in samples from East and Southeast Asia, Australia, Melanesia, Polynesia, and Micronesia for the purpose of assessing the biological affinities and possible origins of these populations. A clear separation between Australomelanesians and other populations from East and Southeast Asia and the Pacific is evident. The craniofacial variations suggest that the generalized Asian populations (Negritos, Dayaks, Lesser Sunda Islands, etc.) represent at least part of the morphological background of not only the majority of present Southeast Asians, but also the Neolithic Jomon people and their lineage in Japan, Polynesians, and western Micronesians. The original craniofacial features of Southeast Asians may have occurred as the result of convergent microevolution due to similar environmental conditions such as tropical rain forest. This supports the local-evolution hypothesis for modern Southeast Asian craniofacial features. © 1993 Wiley-Liss, Inc.     

Melanesian and Asian origins of Polynesians: mtDNA and Y chromosome gradients across the Pacific

The human settlement of the Pacific Islands represents one of the most recent major migration events of mankind. Polynesians originated in Asia according to linguistic evidence or in Melanesia according to archaeological evidence. To shed light on the genetic origins of Polynesians, we investigated over 400 Polynesians from 8 island groups, in comparison with over 900 individuals from potential parental populations of Melanesia, Southeast and East Asia, and Australia, by means of Y chromosome (NRY) and mitochondrial DNA (mtDNA) markers. Overall, we classified 94.1% of Polynesian Y chromosomes and 99.8% of Polynesian mtDNAs as of either Melanesian (NRY-DNA: 65.8%, mtDNA: 6%) or Asian (NRY-DNA: 28.3%, mtDNA: 93.8%) origin, suggesting a dual genetic origin of Polynesians in agreement with the "Slow Boat" hypothesis. Our data suggest a pronounced admixture bias in Polynesians toward more Melanesian men than women, perhaps as a result of matrilocal residence in the ancestral Polynesian society. Although dating methods are consistent with somewhat similar entries of NRY/mtDNA haplogroups into Polynesia, haplotype sharing suggests an earlier appearance of Melanesian haplogroups than those from Asia. Surprisingly, we identified gradients in the frequency distribution of some NRY/mtDNA haplogroups across Polynesia and a gradual west-to-east decrease of overall NRY/mtDNA diversity, not only providing evidence for a west-to-east direction of Polynesian settlements but also suggesting that Pacific voyaging was regular rather than haphazard. We also demonstrate that Fiji played a pivotal role in the history of Polynesia: humans probably first migrated to Fiji, and subsequent settlement of Polynesia probably came from Fiji.     

Multiple origins of the mtDNA 9-bp deletion in populations of South India

The origins and genetic affinities of the more than 500 tribal populations living in South Asia are widely disputed. This may reflect differential contributions that continental populations have made to tribal groups in South Asia. We assayed for the presence of the intergenic COII/tRNALys 9-bp deletion in human mtDNA in 646 individuals from 12 caste and 14 tribal populations of South India and compared them to individuals from Africa, Europe, and Asia. The 9-bp deletion is observed in four South Indian tribal populations, the Irula, Yanadi, Siddi, and Maria Gond, and in the Nicobarese. Length polymorphisms of the 9-bp motif are present in the Santal, Khonda Dora, and Jalari, all of whom live in a circumscribed region on the eastern Indian coast. Phylogenetic analyses of mtDNA control region sequence from individuals with the 9-bp deletion indicate that it has arisen independently in some Indian tribal populations. Other 9-bp deletion haplotypes are likely to be of Asian and African origin, implying multiple origins of the 9-bp deletion in South India. These results demonstrate varying genetic affinities of different South Indian tribes to continental populations and underscore the complex histories of the tribal populations living in South Asia. Am J Phys Anthropol 109:147–158, 1999. © 1999 Wiley-Liss, Inc.     

Genetic Structure of Tibeto-Burman Populations of Bangladesh: Evaluating the Gene Flow along the Sides of Bay-of-Bengal

Human settlement and migrations along sides of Bay-of-Bengal have played a vital role in shaping the genetic landscape of Bangladesh, Eastern India and Southeast Asia. Bangladesh and Northeast India form the vital land bridge between the South and Southeast Asia. To reconstruct the population history of this region and to see whether this diverse region geographically acted as a corridor or barrier for human interaction between South Asia and Southeast Asia, we, for the first time analyzed high resolution uniparental (mtDNA and Y chromosome) and biparental autosomal genetic markers among aboriginal Bangladesh tribes currently speaking Tibeto-Burman language. All the three studied populations; Chakma, Marma and Tripura from Bangladesh showed strikingly high homogeneity among themselves and strong affinities to Northeast Indian Tibeto-Burman groups. However, they show substantially higher molecular diversity than Northeast Indian populations. Unlike Austroasiatic (Munda) speakers of India, we observed equal role of both males and females in shaping the Tibeto-Burman expansion in Southern Asia. Moreover, it is noteworthy that in admixture proportion, TB populations of Bangladesh carry substantially higher mainland Indian ancestry component than Northeast Indian Tibeto-Burmans. Largely similar expansion ages of two major paternal haplogroups (O2a and O3a3c), suggested that they arose before the differentiation of any language group and approximately at the same time. Contrary to the scenario proposed for colonization of Northeast India as male founder effect that occurred within the past 4,000 years, we suggest a significantly deep colonization of this region. Overall, our extensive analysis revealed that the population history of South Asian Tibeto-Burman speakers is more complex than it was suggested before.     

Phylogeography and ethnogenesis of aboriginal Southeast Asians

Studying the genetic history of the Orang Asli of Peninsular Malaysia can provide crucial clues to the peopling of Southeast Asia as a whole. We have analyzed mitochondrial DNA (mtDNAs) control-region and coding-region markers in 447 mtDNAs from the region, including 260 Orang Asli, representative of each of the traditional groupings, the Semang, the Senoi, and the Aboriginal Malays, allowing us to test hypotheses about their origins. All of the Orang Asli groups have undergone high levels of genetic drift, but phylogeographic traces nevertheless remain of the ancestry of their maternal lineages. The Semang have a deep ancestry within the Malay Peninsula, dating to the initial settlement from Africa >50,000 years ago. The Senoi appear to be a composite group, with approximately half of the maternal lineages tracing back to the ancestors of the Semang and about half to Indochina. This is in agreement with the suggestion that they represent the descendants of early Austroasiatic speaking agriculturalists, who brought both their language and their technology to the southern part of the peninsula approximately 4,000 years ago and coalesced with the indigenous population. The Aboriginal Malays are more diverse, and although they show some connections with island Southeast Asia, as expected, they also harbor haplogroups that are either novel or rare elsewhere. Contrary to expectations, complete mtDNA genome sequences from one of these, R9b, suggest an ancestry in Indochina around the time of the Last Glacial Maximum, followed by an early-Holocene dispersal through the Malay Peninsula into island Southeast Asia.     

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

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.     

Mitochondrial and nuclear genetic relationships among Pacific Island and Asian populations.

Mitochondrial and autosomal short tandem-repeat (STR) genetic distances among 28 Pacific Island and Asian populations are significantly correlated (r=.25, P<.01) but describe distinct patterns of relationships. Maternally inherited-mtDNA data suggest that Remote Oceanic Islanders originated in island Southeast Asia. In contrast, biparental STR data reveal substantial genetic affinities between Remote Oceanic Islanders and Near Oceanic populations from highland Papua New Guinea and Australia. The low correlation between maternal and biparental genetic markers from the same individuals may reflect differences in genome-effective population sizes or in sex-biased gene flow. To explore these possibilities, we have examined genetic diversity, gene flow, and correlations among genetic, linguistic, and geographic distances within four sets of populations representing potential geographic and cultural spheres of interaction. GST estimates (a measure of genetic differentiation inversely proportional to gene flow) from mtDNA sequences vary between 0.13 and 0.39 and are typically five times greater than GST estimates from STR loci (0.05-0.08). Significant correlations (r>.5, P<.05) between maternal genetic and linguistic distances are coincident with high mtDNA GST estimates (>0.38). Thus, genetic and linguistic distances may coevolve, and their correspondence may be preserved under conditions of genetic isolation. A significant correlation (r=.65, P<.01) between biparental genetic and geographic distances is coincident with a low STR GST estimate (0.05), indicating that isolation by distance is observed under conditions of high nuclear-gene flow. These results are consistent with an initial settlement of Remote Oceania from island Southeast Asia and with extensive postcolonization male-biased gene flow with Near Oceania.     

Phylogeography and population structure of the Japanese wild boar Sus scrofa leucomystax: mitochondrial DNA variation

Phylogeographic characteristics and population structure of Japanese wild boar (Sus scrofa leucomystax) were investigated using mitochondrial DNA (mtDNA) sequence data. Sixteen Japanese wild boar haplotypes detected from partial sequences of the mtDNA control region (574-bp) from 180 Japanese wild boar specimens from 10 local populations on Honshu, Shikoku, and Kyushu islands and 41 haplotypes from other S. scrofa were analyzed using the neighbor-joining method. The Japanese wild boars were more closely related to Northeast Asian wild boars from Mongolia than to the other Asian continental S. scrofa. The Japanese and Northeast Asian wild boars were not significantly distinguished by corrected average pairwise difference analysis. The ancestors of Japanese wild boars are suggested to have been part of the continental S. scrofa population that spread from Southeast to Northeast Asia during the Middle to Late Pleistocene. The Japanese wild boar mtDNA haplotype cladogram shows 95% parsimoniously plausible branch connections supporting three sympatric clades. Nested clade analysis indicates that these three clades are the result of distinct historical events or gene flow. The present population of Japanese wild boars may have been formed by a few independent migrations of distinct clades from the continent with subsequent mixing on the Japanese Islands.     

Mitochondrial DNA diversity in Southeast Asian populations

In a previous study of Southeast Asian genetic variation, we characterized mitochondrial DNAs (mtDNAs) from six populations through high-resolution restriction fragment length polymorphism (RFLP) analysis. Our analysis revealed that these Southeast Asian populations were genetically similar to each other, suggesting they had a common origin. However, other patterns of population associations also emerged. Haplotypes from a major founding haplogroup in Papua New Guinea were present in Malaysia; the Vietnamese and Malaysian aborigines (Orang Asli) had high frequencies of haplogroup F, which was also seen in most other Southeast Asian populations; and haplogroup B, defined by the Region V 9-base-pair deletion, was present throughout the region. In addition, the Malaysian and Sabah (Borneo) aborigine populations exhibited a number of unique mtDNA clusters that were not observed in other populations. Unfortunately, it has been difficult to compare these patterns of genetic diversity with those shown in subsequent studies of mtDNA variation in Southeast Asian populations because the latter have typically sequenced the first hypervariable segment (HVS-I) of the control region (CR) sequencing rather than used RFLP haplotyping to characterize the mtDNAs present in them. For this reason, we sequenced the HVS-I of Southeast Asian mtDNAs that had previously been subjected to RFLP analysis, and compared the resulting data with published information from other Southeast Asian and Oceanic groups. Our findings reveal broad patterns of mtDNA haplogroup distribution in Southeast Asia that may reflect different population expansion events in this region over the past 50,000-5,000 years.