By Andrea Tiajungla Langstieh
Immigration issues found a new lease of life this past year with a number of parties in Meghalaya resurrecting their concerns about paperless interlopers just in time to juice up pre-election zeal. As opposed to noisy and violent war cries of ‘Us versus Them’, the science of migration in the Northeast is a fascinating subject that is only just beginning to throw up answers to our past.
Northeast India is one of many microcosms in the country with its cultural, biological and linguistic complexities. Colonial era studies made the first impressions in the region’s ethnographic literature through ethnic and racial classifications. Linguistically, the area was classified into people belonging to Indo-European, Tibeto-Burman and Austro-Asiatic families. This was followed by micro evolutionary studies involving collaborative efforts to corroborate genetic, anthropological and linguistic information through DNA markers in the population.
The story of how the Indian subcontinent came to be populated by a series of migrations is sustained by much scientific study. Of these, Darwin’s widely accepted African model of migration occupies pride of place. Yet, the ‘out of Africa’ contention of entrance into India via a sea route or land has until now, not been entirely clear. Along with the Mundari and Mon-Khmer of South and Southeast Asia, the Khasi-Khmuic form a part of the Austro-Asiatic group of languages and are possibly one of the earliest migrants arriving some 65,000 years BP. The hypothesis is that the Austro-Asiatics originated out of Africa and spread to parts of Asia and Europe. Scientists have studied the Y-chromosome haplogroups and mitochondrial DNA (mtDNA) to reconstruct probable past human migratory routes and thereby support macro evolutionary ideas. This is because the Y-chromosome remains unchanged when passing from father to son and mtDNA is similarly used to trace the maternal line. Both can be employed to differentiate between groups like the Khasis and the Tibeto-Burmans, the latter named after its largest speaking members from Tibet and Myanmar.
Since Northeast India is the only region which currently forms a bridge of land between the Indian subcontinent and Southeast Asia, the general belief is that it is an important passage for the initial peopling of East Asia contributing to an admixture of genes . However, a study in 2004 published in the Oxford journal Molecular Biology and Evolution observed ‘genetic discontinuity’ between Northeast Indian groups and other Indian groups and suggested that Northeast India might have acted as a geographic barrier rather than a facilitator for human migrations between the Indian subcontinent and East or Southeast Asia.
Not everyone was convinced by the suggestion. The linguistic connection of Mon-Khmer among the Austro-Asiatics in India (including the Nicobarese of the Andaman and Nicobar islands), Northeast India and the whole of Southeast Asia offered tantalising signs of a genetic link. The practice of matrilineal descent and matrilocal practice of residence amongst the Khasis and Tibeto-Burman speaking Garos was also at odds with the patrilineal and patrilocal practices of neighbours in the region. It was felt that this extreme cultural and linguistic diversity implied a high degree of genetic heterogeneity possibly due to the passage of diverse populations through the region.
Therefore, a subsequent study conducted by Indian scientists from Hyderabad in collaboration with the Department of Anthropology, North Eastern Hill University at Shillong, extended the framework of testing this hypothesis to adequately represent Northeast people. Unlike the earlier study which included only a few Tibeto-Burman groups and other Indian populations with possibly no genetic link with East Asians, samples were collected from Tibeto-Burmans, Indian Austro-Asiatics, Khasis and Garos. These were compared with previous data on Mundaris, Nicobarese, Indo-Europeans and other South and Southeast Asian populations. This allowed a more expansive exploration of the missing genetic link between the Indian and Southeast Asian populations. As hypothesized, the idea of genetic continuity between the two populations was supported by evidence from the Y-chromosome haplogroup O-M95 which suggested a common paternal heritage for Austro-Asiatics. The study found this haplogroup the most widespread in all the Austro-Asiatic populations.
Interestingly, though ethnically similar to the Khasis, when compared to them the Garos and other Tibeto-Burmans in India showed a low frequency of O-M95 and a divergence of certain mtDNA. This suggested that the Khasis had a distinct genetic origin and a separate migration as compared to the Tibeto-Burmans. The results also indicated that the haplogroup O-M95 had originated in the Indian Austro-Asiatic population 65,000 years BP and not in Southeast Asia as previously thought. 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 the Andaman and Nicobar Islands at a much later point in time.
Research groups from the Centre for Cellular & Molecular Biology in Hyderabad and the Indian Statistical Institute in Kolkata are still probing molecular genetics with larger sample sizes to widen the representation of the Tibeto-Burman population in their tracing of Northeast Indians. These researchers say that pre-historic archaeological findings would augment their investigation. The discovery of late Palaeolithic & Neolithic stone tools recovered from sites in the Garo Hills besides Nagaland, Manipur, Arunachal Pradesh and other states would help shed more light on the record of peopling in the region. However, challenges of climate and terrain, the lack of skilled researchers and inadequate funding mean that it will be sometime yet before we get a detailed picture of modern man’s dispersal across the South Asian corridor.
(The author is a lawyer currently based in Mumbai)