Novel 4,400-year-old ancestral component in a tribe speaking a Dravidian language:
Research has shown that the present-day population on the Indian subcontinent derives its ancestry from at least three components identified with pre-Indo-Iranian agriculturalists once inhabiting the Iranian plateau, pastoralists originating from the Pontic-Caspian steppe and ancient hunter-gatherer related to the Andamanese Islanders. The present-day Indian gene pool represents a gradient of mixtures from these three sources. However, with more sequences of ancient and modern genomes and fine structure analyses, we can expect a more complex picture of ancestry to emerge. In this study, we focus on Dravidian linguistic groups to propose a fourth putative source which may have branched out from the basal Middle Eastern component that gave rise to the Iranian plateau farmer related ancestry. The Elamo-Dravidian theory and the linguistic phylogeny of the Dravidian family tree provide chronological fits for the genetic findings presented here. Our findings show a correlation between the linguistic and genetic lineages in language communities speaking Dravidian languages when they are modelled together. We suggest that this source, which we shall call ‘Proto-Dravidian’ ancestry, emerged around the dawn of the Indus Valley civilisation. This ancestry is distinct from all other sources described so far, and its plausible origin not later than 4,400 years ago on the region between the Iranian plateau and the Indus valley supports a Dravidian heartland before the arrival of Indo-European languages on the Indian subcontinent. Admixture analysis shows that this Proto-Dravidian ancestry is still carried by most modern inhabitants of the Indian subcontinent other than the tribal populations. This momentous finding underscores the importance of population-specific fine structure studies. We also recommend informed sampling strategies for biobanks and to avoid oversimplification of ancestral reconstruction. Achieving this requires interdisciplinary collaboration.
Not definitive, but I think this shows the value of greater sampling in Indian subcontinental populations.
Better genetic data is nice and solid. The historical linguistic analysis, less so. A lot of the linguistic analysis hangs on dubious assumptions: (1) that Brahui is a part of ancestral Dravidian territorial extent rather than representing elite driven language shift ca. 1000 CE; (2) that the Harappan civilization spoke Dravidian, rather than their own non-Dravidian, non-Indo-European, non-Austroasiatic language; (3) that ties to the Iranian peninsula are sufficient to support a linguistic connection between the Elamite language of SW Iran and the Dravidian languages. The first two are very likely false assumptions, the third has no foundation. It also ignore the timing of admixture events in South Asia with Indo-Europeans and seemingly short time depth of the Dravidian language family despite its correlation with the Onge-like Ancestral South Indian ancestry, that demands an explanation better than the one provided.
A better solution is that: (1) Dravidian emerged in the South Indian Neolithic ca. 2500 BCE perhaps from a local indigenous language that gained supremacy at that point OR perhaps from some outside linguistic influence (perhaps from the parts of Africa where some of the key South Indian Neolithic crops have their origins), (2) Dravidian is not even in the same language family as Harappan, (3) Brahui is a result of elite language shift ca. 1000 CE (as are other North Dravidian languages), (4) the Elamite language is unrelated to Dravidian, (5) Dravidian has less internal variability because of extreme contraction of the Dravidian range due to Indo-European (call it Sanskrit) expansion that killed most of its internal variation followed by a Dravidian reconquest that restored Dravidian languages to most of their current range but only the version that survived IE conquest in a sole redoubt probably about midway up the Deccan Peninsula — the IE conqueror’s religion struck after the reconquest, but their language did not.
The bit of genetic detail I’d like more data on is the distribution and phylogeny and genetic mutation age depth of Y-DNA T in East Central India, which still lacks of a good explanation.
An important part of this will be the proposed TMRCA of Elamo-Dravidian languages. Supposedly Brahui is put closer to Elamite tha to Dravidian languages in at least 1 proposal. This is a problem because the TMRCA of Brahui and Dravidian languages is only 4500 years ago. So they need to rework things for a TMRCA on the order of 10,000 years instead.
Secondly, from an anthropological and archeological viewpoint, there is a discontinuity in copper age Mehrgarh. Neolithic Mehrgarhites were closer to Mesolithic Ganga people than to Copper age Mehrgarhites. So separate Iran-like sources (Iran hg vs Iran farmer) makes sense and I have believed this for some time.
However this new study doesn’t really provide much info other than here be dragons. For confirmation, there needs to be a better sampling of mesolithic eastern Iran, mesolithic North India + Pakistan ad also Neolithic + chalcolithic North India and Pakistan. There is plenty of copper age sampling in Eastern Iran and it indicates a near replacement of local HGs by western Iranian farmers. Although the extent extent of the replacement seems to not be too high since farmers typically outnumber HGs 100 to 1, and there is ~10% hg ancestry in copper age Iranians.
“The time depth of the shared ancestry between the Koraga and Early Neolithic Ganj Dareh 10,000 years ago coincides with the time ascribed by linguists to the hypothetical Elamo-Dravidian linguistic phylum in the Early Holocene and matches geographically with the Elamo-Dravidian homeland in the Zagros mountains, as proposed by McAlpin (1981). ”
“We suggest that this source, which we shall call ‘Proto-Dravidian’ ancestry, emerged around the dawn of the Indus Valley civilisation. This ancestry is distinct from all other sources described so far, and its plausible origin not later than 4,400 years ago on the region between the Iranian plateau and the Indus valley supports a Dravidian heartland before the arrival of Indo-European languages on the Indian subcontinent. Admixture analysis shows that this Proto-Dravidian ancestry is still carried by most modern inhabitants of the Indian subcontinent other than the tribal populations.”
This 4400/4500 vs 10000 dilemma needs to be addressed. I think one solution could be the hypothesis that the Pre-Proto-Dravidian languages arrived into South Asia in the Copper Age, long after the original Iran-like signal arrived, then proto-Dravidian emerged out of this and spread southward, while the Indus valley back up in North India and Pakistan developed out of a fusion between the new copper age farmer (+AASI admixed?) migratory stock and the older Iran HG + AASI admixed stock, with the latter being more prominent on the eastern side of the IVC. Also, for this to work, they’d need to put Brahui in the Dravidian clade and not the Elamite clade, otherwise, a 4500 bp tmrca would be needed and a copper age migration wouldn’t work as an explanation, it would have to be a separate bronze age migration into South Asia, for which I do not think we have physical evidence yet.