Y-chromosome evidence suggests a common paternal heritage of Austro-Asiatic populations

Abstract

Background: The Austro-Asiatic linguistic family, which is considered to be the oldest of all the families in India, has a substantial presence in Southeast Asia. However, the possibility of any genetic link among the linguistic sub-families of the Indian Austro-Asiatics on the one hand and between the Indian and the Southeast Asian Austro-Asiatics on the other has not been explored till now. Therefore, to trace the origin and historic expansion of Austro-Asiatic groups of India, we analysed Y-chromosome SNP and STR data of the 1222 individuals from 25 Indian populations, covering all the three branches of Austro-Asiatic tribes, viz. Mundari, Khasi-Khmuic and Mon-Khmer, along with the previously published data on 214 relevant populations from Asia and Oceania.

Results: Our results suggest a strong paternal genetic link, not only among the subgroups of Indian Austro-Asiatic populations but also with those of Southeast Asia. However, maternal link based on mtDNA is not evident. The results also indicate that the haplogroup O-M95 had originated in the Indian Austro-Asiatic populations ~65,000 yrs BP (95% C.I. 25,442-132,230) and their ancestors carried it further to Southeast Asia via the Northeast Indian corridor. Subsequently, in the process of expansion, the Mon-Khmer populations from Southeast Asia seem to have migrated and colonized Andaman and Nicobar Islands at a much later point of time.

Conclusion: Our findings are consistent with the linguistic evidence, which suggests that the linguistic ancestors of the Austro-Asiatic populations have originated in India and then migrated to Southeast Asia.

Figure 1

Map showing present-day distribution of Austro-Asiatic groups (modified from van Driem [2]) and the schematic representation of the routes of migration of the different Austro-Asiatic linguistic subgroups of India.

Figure 2

Rooted maximum-parsimony tree of haplogroups defined by binary markers along with their frequency in different groups.

Figure 3

Rooted maximum-parsimony tree of sub-haplogroups of O-M122 along with their frequencies in Khasi and Garo samples.

Figure 4

Median-Joining network of Y-STR haplotypes of O-M95 haplogroup. Samples with data on some STRs missing were excluded and the remaining 564 chromosomes were analysed. Circles represent haplotypes with area proportional to their frequency. Microsatellite mutations are represented by black lines.

Figure 5

The isofrequency maps portraying spatial distribution of Haplogroups in Asia and Oceania for O-M95 and O-M122 (data are from [14-16, 18-30]). For O-M95, Nicobarese samples were excluded. The dots indicate the populations and the regions from where it was sampled.