Genetic and linguistic non-correspondence suggests evidence for collective social climbing in the Kol tribe of South Asia

Abstract

Both classical and recent genetic studies have unanimously concluded that the genetic landscape of South Asia is unique. At long distances the 'isolation-by-distance' model appears to correspond well with the genetic data, whereas at short distances several other factors, including the caste, have been shown to be strong determinant factors. In addition with these, tribal populations speaking various languages add yet another layer of genetic complexity. The Kol are the third most populous tribal population in India, comprising communities speaking Austroasiatic languages of the Northern Munda branch. Yet, the Kol have not hitherto undergone in-depth genetic analysis. In the present study, we have analysed two Kol groups of central and western India for hundreds thousands of autosomal and several mitochondrial DNA makers to infer their fine genetic structure and affinities to other Eurasian populations. In contrast, with their known linguistic affinity, the Kol share their more recent common ancestry with the Indo-European and Dravidian speaking populations. The geographic-genetic neighbour tests at both the temporal and spatial levels have suggested some degree of excess allele sharing of Kol1 with Kol2, thereby indicating their common stock. Our extensive analysis on the Kol ethnic group shows South Asia to be a living genetics lab, where real-time tests can be performed on existing hypotheses. The Indian subcontinent is renowned for the cultural, linguistic and genetic diversity of its inhabitants 1,2. This diversity has mainly arisen, in part, through long term human settlement, social customs and genetic drift 3-5. Broadly, Indian populations can be categorised as the castes, tribes, linguistic and religious communities. Presently, India counts hundreds of tribal groups, belonging to four major language families; Austroasiatic, Dravidian, Indo-European and Tibeto-Burman 6,7. Kol is one of them, with their major concentration in Central India (Fig. 1A). Kol is another name for Ho, whose language is a member of the Kherwarian cluster within the Northern Branch of the Munda subgroup of Austroasiatic language family 7-9. In fact, the language family came to be known as 'Mon-Khmer-Kolarian' when Francis Mason first identified that Kol and the other Munda languages were related to the Mon language of eastern Burma and Thailand in 1854. He suggested that these Munda or 'Kolarian' languages of India and the 'Mon-Annam' languages of Southeast Asia, collectively belonged to one and the same language family 10. The language family was given its current name ' Austroasiatic' in 1904 by Wilhelm Schmidt 11-15 .