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Subject: PubMed abstract: Y and mtDNA in India
Date: Wed, 9 Aug 2006 20:59:30 EDT


BMC Genet. 2006 Aug 7;7(1):42 [Epub ahead of print]

Genetic affinities among the lower castes and tribal groups of India:
Inference from Y chromosome and mitochondrial DNA.

Thanseem I, Thangaraj K, Chaubey G, Singh VK, Bhaskar LV, Reddy MB, Reddy AG,
Singh L.

ABSTRACT: BACKGROUND: India is a country with enormous social and cultural
diversity due to its positioning on the crossroads of many historic and
pre-historic human migrations. The hierarchical caste system in the Hindu society
dominates the social structure of the Indian populations. The origin of the caste
system in India is a matter of debate with many linguists and anthropologists
suggesting that it began with the arrival of Indo-European speakers from
Central Asia about 3500 years ago. Previous genetic studies based on Indian
populations failed to achieve a consensus in this regard. We analysed the
Y-chromosome and mitochondrial DNA of three tribal populations of southern India,
compared the results with available data from the Indian subcontinent and tried to
reconstruct the evolutionary history of Indian caste and tribal populations.
RESULTS: No significant difference was observed in the mitochondrial DNA between
Indian tribal and caste populations, except for the presence of a higher
frequency of west Eurasian-specific haplogroups in the higher castes, mostly in the
north western part of India. On the other hand, the study of the Indian Y
lineages revealed distinct distribution patterns among caste and tribal
populations. The paternal lineages of Indian lower castes showed significantly closer
affinity to the tribal populations than to the upper castes. The frequencies of
deep-rooted Y haplogroups such as M89, M52, and M95 were higher in the lower
castes and tribes, compared to the upper castes. CONCLUSIONS: The present
study suggests that the vast majority (>98%) of the Indian maternal gene pool,
consisting of Indio-European and Dravidian speakers, is genetically more or less
uniform. Invasions after the late Pleistocene settlement might have been
mostly male-mediated. However, Y-SNP data provides compelling genetic evidence for
a tribal origin of the lower caste populations in the subcontinent. Lower
caste groups might have originated with the hierarchical divisions that arose
within the tribal groups with the spread of Neolithic agriculturalists, much
earlier than the arrival of Aryan speakers. The Indo-Europeans established
themselves as upper castes among this already developed caste-like class structure
within the tribes.

PMID: 16893451 [PubMed - as supplied by publisher]



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