Tony Joseph in The Hindu:
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.
This may come as a surprise to many — and a shock to some — because the dominant narrative in recent years has been that genetics research had thoroughly disproved the Aryan migration theory. This interpretation was always a bit of a stretch as anyone who read the nuanced scientific papers in the original knew. But now it has broken apart altogether under a flood of new data on Y-chromosomes (or chromosomes that are transmitted through the male parental line, from father to son).
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.