The primary source of ancestry in modern South Indians is a prehistoric genetic gradient between people related to early hunter-gatherers of Iran and Southeast Asia, a newly published study titled ‘An ancient Harappan genome lacks ancestry from Steppe pastoralists or Iranian farmers’ said.
The paper makes three crucial points, as noted in the Economic Times, The skeletal remains from the Rakhigarhi individual was from a population that is “the largest source of ancestry for South Asians”; the “Iranian related ancestry in South Asia split from Iranian plateau lineage over 12,000 years ago”; the “first farmers of the fertile crescents contributed little to no ancestry to later South Asians”.
The study which involved the inspection of DNA samples of the skeletons found in Rakhigarhi, an Indus Valley Civilisation (IVC) site in Haryana, found no traces of the R1a1 gene or Central Asian ‘steppe’ genes, colloquially called the ‘Aryan gene’. “The population has no detectable ancestry from Steppe pastoralists or from Anatolian and Iranian farmers, suggesting farming in South Asia arose from local foragers rather than from large-scale migration from the West,” the study said.
The study further notes, “After the Indus Valley Civilization’s decline, its people mixed with individuals in the southeast to form one of the two main ancestral populations of South Asia, whose direct descendants live in southern India. Simultaneously, they mixed with descendants of Steppe pastoralists who, starting around 4000 years ago, spread via Central Asia to form the other main ancestral population. The Steppe ancestry in South Asia has the same profile as that in Bronze Age Eastern Europe, tracking a movement of people that affected both regions and that likely spread the distinctive features shared between Indo-Iranian and Balto-Slavic languages.”
The study says that the section of the IVC population that mixed with northwestern groups with Steppe ancestry to form the “Ancestral North Indians”(ANI) and also mixed with southeastern groups to form the “Ancestral South Indians” (ASI), whose direct descendants today live in tribal groups in southern India.
“The Iranian related ancestry in IVC derives from a lineage leading to early Iranian farmers, herders and hunter-gatherers before their ancestors separated, contradicting the hypothesis that the shared ancestry between early Iranians and South Asians reflects a large-scale spread of western Iranian farmers east. Instead, sampled ancient genomes from the Iranian plateau and IVC descend from different groups of hunter-gatherers who began farming without being connected by substantial movement of people,” the paper states. It means that farming was developed in the Indian subcontinent by indigenous populations.
Vagheesh Narasimhan, one of the researchers involved in the study, noted on Twitter, “Our results also contradict the hypothesis that the shared ancestry between early Iranians and South Asians reflects a large-scale spread of western Iranian farmers east.” He added, “Instead, sampled ancient genomes from the Iranian plateau and IVC descend from different groups of hunter-gatherers who began farming without being connected by substantial movement of people.”
Instead, sampled ancient genomes from the Iranian plateau and IVC descend from different groups of hunter-gatherers who began farming without being connected by substantial movement of people.
— Vagheesh Narasimhan (@vagheesh) September 5, 2019
The new study suggests the Iranian-related DNA in both the Indus individuals and modern Indians actually predates the rise of agriculture in Iran by some 2000 years. In other words, that Iranian-related DNA came from interbreeding with 12,000-year-old hunter-gatherers, not more recent farmers, geneticist David Reich from Harvard University explained.
“The paper indicates that there was no Aryan invasion and no Aryan migration and that all the developments right from the hunting-gathering stage to modern times in South Asia were done by indigenous people,” Prof Vasant Shinde, lead author of the paper, told Economic Times.