Reading the paper that has been cited in several postings:
<
http://www.genome.org/cgi/content/abstract/11/6/994>
I'll copy it to make it simple:
Genetic Evidence on the Origins of Indian Caste Populations
Michael Bamshad,1,10,12 Toomas Kivisild,2 W. Scott Watkins,3 Mary E.
Dixon,3 Chris E. Ricker,3 Baskara B. Rao,4 J. Mastan Naidu,4 B.V. Ravi
Prasad,4,5 P. Govinda Reddy,6 Arani Rasanayagam,7 Surinder S. Papiha,8
Richard Villems,2 Alan J. Redd,7 Michael F. Hammer,7 Son V. Nguyen,9
Marion L. Carroll,9 Mark A. Batzer,9,11 and Lynn B. Jorde3
1 Department of Pediatrics, University of Utah, Salt Lake City, Utah
84112, USA; 2 Institute of Molecular and Cell Biology, Tartu
University and Estonian Biocentre, Tartu 51010, Estonia; 3 Department
of Human Genetics, University of Utah, Salt Lake City, Utah 84112,
USA; 4 Department of Anthropology, Andhra University, Visakhapatnam,
Andhra Pradesh, India; 5 Anthropological Survey of India, Calcutta,
India; 6 Department of Anthropology, University of Madras, Madras,
Tamil Nadu, India; 7 Laboratory of Molecular Systematics and
Evolution, University of Arizona, Tucson, Arizona 85721, USA; 8
Department of Human Genetics, University of Newcastle-upon-Tyne, UK; 9
Department of Pathology, Biometry and Genetics, Biochemistry and
Molecular Biology, Stanley S. Scott Cancer Center, Louisiana State
University Health Science Center, New Orleans, Louisiana 70112, USA
The origins and affinities of the ~1 billion people living on the
subcontinent of India have long been contested. This is owing, in
part, to the many different waves of immigrants that have influenced
the genetic structure of India. In the most recent of these waves,
Indo-European-speaking people from West Eurasia entered India from the
Northwest and diffused throughout the subcontinent. They purportedly
admixed with or displaced indigenous Dravidic-speaking populations.
Subsequently they may have established the Hindu caste system and
placed themselves primarily in castes of higher rank. To explore the
impact of West Eurasians on contemporary Indian caste populations, we
compared mtDNA (400 bp of hypervariable region 1 and 14 restriction
site polymorphisms) and Y-chromosome (20 biallelic polymorphisms and 5
short tandem repeats) variation in ~265 males from eight castes of
different rank to ~750 Africans, Asians, Europeans, and other Indians.
For maternally inherited mtDNA, each caste is most similar to Asians.
However, 20%-30% of Indian mtDNA haplotypes belong to West Eurasian
haplogroups, and the frequency of these haplotypes is proportional to
caste rank, the highest frequency of West Eurasian haplotypes being
found in the upper castes. In contrast, for paternally inherited
Y-chromosome variation each caste is more similar to Europeans than to
Asians. Moreover, the affinity to Europeans is proportionate to caste
rank, the upper castes being most similar to Europeans, particularly
East Europeans. These findings are consistent with greater West
Eurasian male admixture with castes of higher rank. Nevertheless, the
mitochondrial genome and the Y chromosome each represents only a
single haploid locus and is more susceptible to large stochastic
variation, bottlenecks, and selective sweeps. Thus, to increase the
power of our analysis, we assayed 40 independent, biparentally
inherited autosomal loci (1 LINE-1 and 39 Alu elements) in all of the
caste and continental populations (~600 individuals). Analysis of
these data demonstrated that the upper castes have a higher affinity
to Europeans than to Asians, and the upper castes are significantly
more similar to Europeans than are the lower castes. Collectively, all
five datasets show a trend toward upper castes being more similar to
Europeans, whereas lower castes are more similar to Asians. We
conclude that Indian castes are most likely to be of proto-Asian
origin with West Eurasian admixture resulting in rank-related and
sex-specific differences in the genetic affinities of castes to Asians
and Europeans. (end copy)
Doesn't an admixture of European-like chromosomes in the higher
castes of India point to the ancestors thereof being intrusive; and
moreover that this shows in the male rather than female chromosomes,
not simply immigrants, but invaders?
Is there any other reasonable interpretation?
Dan