The thorniest, most fought-over question in Indian history is slowly but surely getting answered: did Indo-European language speakers, who called themselves Aryans, stream into India sometime around 2,000 BC – 1,500 BC when the Indus Valley civilisation came to an end, bringing with them Sanskrit and a distinctive set of cultural practices? Genetic research based on an avalanche of new DNA evidence is making scientists around the world converge on an unambiguous answer: yes, they did. Tony Joseph, Hindu TimesInteresting piece in the Hindu Times again illustrating the way that DNA analysis is re-shaping our view of the world.
I have absolutely no expertise in the question of Indo-Aryan migration, nor am I familiar enough with Indian politics to know how how questions of the direction of migration play out domestically. I had always assumed that part of the ethnic difference between the north and south of the country lay in the different migration patterns, with the north open to waves of migration from elsewhere in Eurasia. The latest data would appear to support that view.
Until recently, only data on mtDNA (or matrilineal DNA, transmitted only from mother to daughter) were available and that seemed to suggest there was little external infusion into the Indian gene pool over the last 12,500 years or so. New Y-DNA data has turned that conclusion upside down, with strong evidence of external infusion of genes into the Indian male lineage during the period in question.Tony Joseph suggests that the reason for the difference in mtDNA and Y-DNA data is obvious in hindsight: there was strong sex bias in Bronze Age migrations. In other words, those who migrated were predominantly male and, therefore, those gene flows do not really show up in the mtDNA data. On the other hand, they do show up in the Y-DNA data:
In fact, about 17.5% of Indian male lineage has been found to belong to haplogroup R1a (haplogroups identify a single line of descent), which is today spread across Central Asia, Europe and South Asia. The Pontic-Caspian Steppe is seen as the region from where R1a spread both west and east, splitting into different sub-branches along the way. Genetic analysis suggests that the Indian versions of R1A split of between 2,000 and 1,500 BC.
Postscript 21 June 2017
Ramana, my Indian blogger friend, pointed me to this rebuttal of the Joseph piece, Genetics Might Be Settling The Aryan Migration Debate, But Not How Left-Liberals Believe. My first reaction was that Anil Kumar Suri appeared to be wielding a rather hatchet in what was clearly an ideological dispute that I did not properly understand.
I need to go back to to the Joseph piece and look at the detail of DNA material provided to try to determine what is factual as compared to ideological positioning on both sides. Meantime, some one may be able to explain just what the apparent ideological and political dispute really is..
On a different topic, regular commenter Johnb has pointed me to yet another DNA study, First complete genome data extracted from ancient Egyptian mummies. For later reference.