Origin of Indians

Origin of Indians

Current Biology. Volume 14, Issue 3 , 3 February 2004, Pages 231-235
Independent Origins of Indian Caste and Tribal Paternal Lineages
Richard Cordaux et al.
Abstract
The origins of the nearly one billion people inhabiting the Indian subcontinent and following the customs of the Hindu caste system [1 and 2] are controversial: are they largely derived from Indian local populations (i.e. tribal groups) or from recent immigrants to India? Archaeological and linguistic evidence support the latter hypothesis [2, 3 and 4], whereas recent genetic data seem to favor the former hypothesis [5]. Here, we analyze the most extensive dataset of Indian caste and tribal Y chromosomes to date. We find that caste and tribal groups differ significantly in their haplogroup frequency distributions; caste groups are homogeneous for Y chromosome variation and more closely related to each other and to central Asian groups than to Indian tribal or any other Eurasian groups. We conclude that paternal lineages of Indian caste groups are primarily descended from Indo-European speakers who migrated from central Asia ~3,500 years ago. Conversely, paternal lineages of tribal groups are predominantly derived from the original Indian gene pool. We also provide evidence for bidirectional male gene flow between caste and tribal groups. In comparison, caste and tribal groups are homogeneous with respect to mitochondrial DNA variation [5 and 6], which may reflect the sociocultural characteristics of the Indian caste society.
Indigenous/Non-indigenous Contributions in Y chromosomes
In contrast with the Y chromosome evidence, the mtDNA evidence suggests a common origin of tribal and caste groups [5 and 6]. It is likely that most maternal lineages largely represent the original mtDNA gene pool of India, implying that caste maternal lineages mainly derive from local tribal ancestors [5, 6 and 7].
The current frequency of west Eurasian-typical mtDNAs in Indian caste populations of ~10% [5] and the practice of female infanticide over centuries, perhaps at rates as high as 30%–80% in some groups [22], suggest that (1) the replacement was not completely achieved, consistent with the recent origins of the caste system [2 and 17], and (2) the current frequency of west Eurasian-typical mtDNAs in the Indian caste gene pool may underestimate the ancestral frequency, consistent with the view that the Indo-European migrants were not necessarily mostly males.
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