In the Wikipedia entry about the Y-DNA Haplogroup R1a, so popular among the fans of Indo-Europeans, something has recently changed. We find acknowledged the fact that, notwithstanding various studies suggesting a South Asian origin, still there is a resistance by some researchers:
“R1a and R1a1a are believed to have originated somewhere within Eurasia, most likely in the area from Eastern Europe to South Asia. Several recent studies have proposed that South Asia is the most likely region of origin. But on the other hand, as will be discussed below, some researchers continue to treat modern Indian R1a as being largely due to immigration from the Central Eurasian steppes.”
Below, about the South Asian origin hypothesis, we read:
Below, about the South Asian origin hypothesis, we read:
“A survey study as of December 2009, including a collation of retested Y-DNA from previous studies, concluded that a South Asian R1a1a origin was the most likely proposal amongst the various uncertain possibilities.
On the other hand, other recent studies such as Zhao et al. (2009) continue to treat R1a in modern India as being at least partly due to immigration from the northwest associated with Indoeuropean languages and culture. One argument for this, as stated for example by Thanseem et al. (2006), is that this is implied by the uneven distribution pattern of R1a between castes and regions. Higher castes and more northerly Indian populations are considered to be more directly descended from the populations who brought Indoeuropean languages to India, and they tend to have higher levels of R1a than lower castes, and more southerly populations, while tribal castes and non Indoeuropean speaking groups tend to have the lowest frequencies of R1a. In order to explain exceptions to this pattern, these authors propose that R1a in India is also partly due to earlier movements of people from central Asia.”
Then, I decided to see this study of Zhao et al., which I did not know. The title is Presence of three different paternal lineages among North Indians: A study of 560 Y chromosomes. It concerns only North Indians, and two particular categories of North Indians: Brahmins and Muslims. We read in the introduction:
"India occupies a unique stage in human population evolution because one of the early waves of migration of modern humans was out of Africa, through West Asia, into India (Cann 2001). More recently, about 15 000–10 000 years before present (ybp), when agriculture developed in the Fertile Crescent region that extended from Israel through Northern Syria to Western Iran, there was an eastward wave of human migration (Renfrew 1989; Cavalli-Sforza et al. 1994). It has been postulated that this wave brought the Dravidian language into India (Renfrew 1989). Subsequently, the Indo-European (Aryan) language was introduced into India from the Iranian plateau approximately 4000–3000 ybp, where this language was probably brought by pastoral nomads from the Central Asian steppes (Renfrew 1989). Therefore, linguistic evidence suggests that West Asia and Central Asia were two major geographical sources contributing to the Indian gene pool."
So, we find the 'postulate' of the arrival of the Dravidians with agriculture from West Asia, and the 'probability' of Indo-Europeans as pastoral nomads from the Central Asian steppes. These old theories (supported here by a publication of Renfrew, accepted as authority for unknown reasons), become at the end 'linguistic evidence' which can even suggest the major sources of the Indian gene pool. This entails that linguistic speculation can give some proof about the origin of the major part of the Indian gene pool, which is not justified.
Another significant passage:
"Furthermore, it has been reported (Cordaux et al. 2004) that the Y lineages of Indian castes are more closely related to Central Asians than to Indian tribal populations, suggesting that Indian caste groups are primarily the descendants of Indo-European migrants."
Thus, it is taken for granted that this connection means that the members of Indian castes come from Central Asia (and not that there could also be some movement from India to Central Asia), and there is an equation Central Asians=Indo-Europeans, but what do we know of the languages of Central Asia in the II millennium BC and before? Presently, many men belonging to the Hg R in Central Asia speak Turkic languages, as is acknowledged by the study itself:
"Haplogroup R reflects the impact of expansion and migration of Indo-European pastoralists from Central Asia, thus linking haplogroup frequency to specific historical events (Sengupta et al. 2006). Haplogroup R is widely spread in central Asian Turkic-speaking populations and in eastern European Finno-Ugric and Slavic speakers and is less frequent in populations from the Middle East and Sino-Tibetan regions of northern China (Karafet et al. 1999; Underhill et al. 2000)."
It is really strange that the fundamental study by Sengupta is cited to support the idea that Hg R reflects a migration of Indo-European pastoralists from Central Asia, since the main thesis of that study is that Central Asian impact in South Asia is really limited (italics are mine):
"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."
"The pattern of clustering does not support the model that the primary source of the R1a1-M17 chromosomes in India was Central Asia or the Indus Valley via Indo-European speakers. Further, the relative position of the Indian tribals (fig. 6), the high microsatellite variance among them (table 12), the estimated age (14 KYA) of microsatellite variation within R1a1 (table 11), and the variance peak in western Eurasia (fig. 4) are entirely inconsistent with a model of recent gene flow from castes to tribes and a large genetic impact of the Indo-Europeans on the autochthonous gene pool of India. Instead, our overall inference is that an early Holocene expansion in northwestern India (including the Indus Valley) contributed R1a1-M17 chromosomes both to the Central Asian and South Asian tribes prior to the arrival of the Indo-Europeans. The results of our more comprehensive study of Y-chromosome diversity are in agreement with the caveat of Quintana-Murci et al. (2001, p. 541), that “more complex explanations are possible,” rather than their simplistic conclusion that HGs J and R1a1 reflect demic expansions of southwestern Asian Dravidian-speaking farmers and Central Asian Indo-European–speaking pastoralists."
So, even the 'postulate' of the West Asian 'agricultural' origin of Dravidians is refuted by Sengupta's study, which appears to accept without discussion the traditional theory about the coming of Indo-Europeans, but gives no genetic support for it. Actually, this 'early Holocene expansion in northwestern India' could have something to do with the diffusion of Indo-European languages, in connection with the emergence of agriculture, which is placed in the Early Holocene (see here). The only thing said about an origin of the Hg R out of South Asia is this:
"The phylogeography of the HG R*-M207 spans Europe, the Caucasus, West Asia, Central Asia, and South Asia; therefore, the hypothesis that there is an HG R*-M207 expansion locus central to all these regions is both plausible and parsimonious. This is consistent with our observation that HG R*-M207 is observed at a maximum of 3.4% frequency in Baluchistan and Punjab regions, whereas, in inner India, it is 0.3%."So, it can even be that all Hg R comes from North-western South Asia. More recently, a study by Firasat et al. (2007), R* has been found in 10.3% (10/97) of a sample of Burusho (speakers of an isolated non-IE language, Burushaski), 6.8% (3/44) of a sample of Kalash, and 1.0% (1/96) of a sample of Pashtuns from northern Pakistan.
But Zhao's study appears to ignore all this, and finally asserts:
"we suggest that Central Asia is the most likely source of North Indian Y lineage considering the historical and genetic background of North India (Karve 1968; Balakrishnan 1978)."
So, it seems that publications of the '60s and '70s give us the final authority on the genetic background of North India.
Now, we do not want to deny genetic differences between castes and tribals, but there are other explanations. Castes developed in the agrarian civilization of Northern India (and present Pakistan), and then spread with Brahmanism to Eastern and Southern India. So, it is to be expected that Hgs more connected with Western and Central Asia like J and R are more frequent in castes than in tribals.
J because it is originally connected with West Asian agriculturists, and R because it is probably connected with agriculturists, pastoralists and metal-workers from North-western South Asia and maybe also Afghanistan, which is an ancient area of Neolithic and rich in R1a.
And if some Turks of Central Asia have a high frequency of R1a, it can be because of the migrations of Iranians and Tocharians in those regions from the South and West. Turks arrived later from North-Eastern Asia, with some Mongolic features which are not a legacy of R1a, and mingled with the previous Indo-European speakers.
I would like to add another note about the relation between India and Central Asia. It has been generally thought that horse came to India from Central Asia, where it was firstly domesticated 5500 years ago in Kazakhstan. But a very recent discovery in Arabia can change the picture. In the site of Al-Magar in Central Arabia archaeologists have found remains of a Neolithic civilization dated back to 9000 years ago (see here, cfr. here). In that site, there are many images, drawn and sculpted, of the horse.
One is this, around 1 m. in length, with possible signs of harness. A cave drawing appears to show a man riding a horse. The shape of these horses reminds the famous Arabian horse... now, Indian horse breeds like Marwari and Kathiawari are akin to Arabian horses, and there is an interesting detail which was noted by Rajaram (I am not a follower of Rajaram, but useful remarks are always welcome): Vedic horse (see RV I.162.18) has 34 ribs, differently from the average Central Asian horse, who has 36 ribs. Now, what is not observed by Rajaram, as far as I know, is that the Arabian horse has typically 17 pairs of ribs (see here). Moreover, horse in Indian mythology comes from the ocean, and at Ajanta we find a picture with horses brought in a ship (see here). So, maybe the first horses came to India directly from Arabia and not from Central Asia, at least in the 3rd millennium BC, when they appear in Harappan sites (often near the coast)...