February 20, 2006

Y-chromosomes of Eastern India

This paper seems to take an opposite position compared to the other one by the same authors. From the paper:
Haplogroups H* and R2 were the two most common paternal lineages found in Orissa, although the frequency varied among populations. Caste populations displayed clear imprints of M17 (R1a1) at 38.5% and M172 (J2) at 5.7%, which are also found in high frequency in Eastern Europe and Central Asia (Semino et al., 2000; Underhill et al., 2000; Wells et al., 2001) and in the Middle East (Quintana-Murci et al., 2001), respectively. Among the Austro-Asiatic tribal groups, all the Juang Y-chromosomes exhibited the O2a lineage, which is common in eastern Asia (Karafet et al., 2001), while the Saora harbored lineages consisting of the F*, H, O2a, and P* haplogroups. The C haplogroup, which was associated with an early coastal migration of modern humans (Underhill et al., 2001), was found at a low frequency (1.6%) in the Paroja, and was completely absent in Austro-Asiatic tribes and the caste populations.
As I have argued in my review of Indian Y-chromosome variation before, the origin of M17-related Y-chromosomes is not an either-or proposition between Central Asia and India, but rather it is possible that a group of such chromosomes are of Paleolithic antiquity in India, while a subset may have been of more recent introduction. No doubt, more light will be shed on this matter once the phylogeny of M17 is better developed.

Am J Phys Anthropol. 2006 Feb 16; [Epub ahead of print]

Phylogeography of mitochondrial DNA and Y-Chromosome haplogroups reveal asymmetric gene flow in populations of Eastern India.

Sahoo S, Kashyap VK.

Polymorphisms in mitochondrial (mt) DNA and Y-chromosomes of seven socially and linguistically diverse castes and tribes of Eastern India were examined to determine their genetic relationships, their origin, and the influence of demographic factors on population structure. Samples from the Orissa Brahmin, Karan, Khandayat, Gope, Juang, Saora, and Paroja were analyzed for mtDNA hypervariable sequence (HVS) I and II, eight Y-chromosome short tandem repeats (Y-STRs), and lineage-defining mutations diagnostic for Indian- and Eurasian-specific haplogroups. Our results reveal that haplotype diversity and mean pairwise differences (MPD) was higher in caste groups of the region (>0.998, for both systems) compared to tribes (0.917-0.996 for Y-STRs, and 0.958-0.988 for mtDNA haplotypes). The majority of paternal lineages belong to the R1a1, O2a, and H haplogroups (62.7%), while 73.2% of maternal lineages comprise the Indian-specific M*, M5, M30, and R* mtDNA haplogroups, with a sporadic occurrence of West Eurasian lineages. Our study reveals that Orissa Brahmins (a higher caste population) have a genetic affinity with Indo-European speakers of Eastern Europe, although the Y-chromosome data show that the genetic distances of populations are not correlated to their position in the caste hierarchy. The high frequency of the O2a haplogroup and absence of East Asian-specific mtDNA lineages in the Juang and Saora suggest that a migration of Austro-Asiatic tribes to mainland India was exclusively male-mediated which occurred during the demographic expansion of Neolithic farmers in southern China. The phylogeographic analysis of mtDNA and Y-chromosomes revealed varied ancestral sources for the diverse genetic components of the populations of Eastern India.


No comments: