What follows is comments by Dr. Shiv Sastry to a twitter comment (via/based on another blog article).
Deliberate or not, such nonsense is been repeated time and again.
Dr. Shiv Sastry responds, aptly, via two referenced journal articles.
(I am reproducing it for general reading but also as handy reference when eventually I get around the use of the genetic evidence for corroborating (and as appropriate – falsifying) various theories related to ancient Indian history)
Here it goes….
1 can estimate that approximately at least 50% of the Y-chromosomes of varNa populations as a group originated from invading Aryan males
Dr. SS comments… (very apt)
Sengupta S, Zhivotovsky LA, King R, Mehdi SQ, Edmonds CA, Chow CE et al. (2006) Polarity and tem-
porality of high-resolution y-chromosome distributions in India identify both indigenous and exogenous
expansions and reveal minor genetic influence of Central Asian pastoralists. Am J Hum Genet 78:202–221.
Although considerable cultural impact on social hierarchy and language in South Asia is attributable to the arrival
of nomadic Central Asian pastoralists, genetic data (mitochondrial and Y chromosomal) have yielded dramatically
conflicting inferences on the genetic origins of tribes and castes of South Asia. We sought to resolve this conflict,
using high-resolution data on 69 informative Y-chromosome binary markers and 10 microsatellite markers from
a large set of geographically, socially, and linguistically representative ethnic groups of South Asia. We found that
the influence of Central Asia on the pre-existing gene pool was minor. The ages of accumulated microsatellite
variation in the majority of Indian haplogroups exceed 10,000–15,000 years, which attests to the antiquity of
regional differentiation. Therefore, our data do not support models that invoke a pronounced recent genetic input
from Central Asia to explain the observed genetic variation in South Asia. R1a1 and R2 haplogroups indicate
demographic complexity that is inconsistent with a recent single history. Associated microsatellite analyses of the
high-frequency R1a1 haplogroup chromosomes indicate independent recent histories of the Indus Valley and the
peninsular Indian region. Our data are also more consistent with a peninsular origin of Dravidian speakers than
a source with proximity to the Indus and with significant genetic input resulting from demic diffusion associated
with agriculture. Our results underscore the importance of marker ascertainment for distinguishing phylogenetic
terminal branches from basal nodes when attributing ancestral composition and temporality to either indigenous
or exogenous sources. Our reappraisal indicates that pre-Holocene and Holocene-era—not Indo-European—expansions have shaped the distinctive South Asian Y-chromosome landscape.
Kivisild T, Rootsi S, Metspalu M, Mastana S, Kaldma K, Parik J et al. (2003) The genetic heritage of the
earliest settlers persists both in Indian tribal and caste populations. Am J Hum Genet 72: 313–332.
Two tribal groups from southern India—the Chenchus and Koyas—were analyzed for variation in mitochondrial
DNA (mtDNA), the Y chromosome, and one autosomal locus and were compared with six caste groups from
different parts of India, as well as with western and central Asians. In mtDNA phylogenetic analyses, the Chenchus
and Koyas coalesce at Indian-specific branches of haplogroups M and N that cover populations of different social
rank from all over the subcontinent. Coalescence times suggest early late Pleistocene settlement of southern Asia
and suggest that there has not been total replacement of these settlers by later migrations. H, L, and R2 are the
major Indian Y-chromosomal haplogroups that occur both in castes and in tribal populations and are rarely found
outside the subcontinent. Haplogroup R1a, previously associated with the putative Indo-Aryan invasion, was found
at its highest frequency in Punjab but also at a relatively high frequency (26%) in the Chenchu tribe. This finding,
together with the higher R1a-associated short tandem repeat diversity in India and Iran compared with Europe
and central Asia, suggests that southern and western Asia might be the source of this haplogroup. Haplotype frequencies of the MX1 locus of chromosome 21 distinguish Koyas and Chenchus, along with Indian caste groups, from European and eastern Asian populations. Taken together, these results show that Indian tribal and caste populations derive largely from the same genetic heritage of Pleistocene southern and western Asians and have received limited gene flow from external regions since the Holocene. The phylogeography of the primal mtDNAand Y-chromosome founders suggests that these southern Asian Pleistocene coastal settlers from Africa would have provided the inocula for the subsequent differentiation of the distinctive eastern and western Eurasian gene pools