New data confirm a long-held but controversial theory that Sanskrit, the ancient language of Northern India, emerged from an earlier language spoken by people in Central Asia, who may have moved into India around 3,500 years ago.
     Study co-author Martin Richards, an archaeo-geneticist at the University of Huddersfield in England, says: "People have been debating the arrival of the Indo-European languages in India for hundreds of years."
     From the earliest days of colonial rule in India, linguists noticed that Sanskrit shared many similarities with languages as disparate as French, English, Farsi (Persian), and Russian, eventually concluding that all derived from a common ancestral language, which they called Indo-European.
     Scholars proposed that a group of people from outside India brought a proto-Sanskrit language to northern India; South Indian languages mostly belong to a different language family.  
     The controversial 'Aryan invasion' theory is the basis for the Indian caste system, and in a bastardised form was incorporated into Nazi ideology.
     Earlier genetic data did not seem to corroborate a dramatic influx into India during the Bronze Age, but past analyses were based on either DNA passed from mothers to daughters, or mutations inherited from both parents but difficult to date.
     Richards and colleagues analysed several types of modern genetic data, including that passed only from father to son. In this way the team was able to link patterns of migration to specific points in time. They found evidence that people began colonising India more than 50,000 years ago, and multiple migrations from the northwest over the last 20,000 years, including people from Anatolia, the Caucasus, and Iran between 9,000 and 5,000 years ago.
     Evidence for one migration points to a group of people who inhabited the grassland between the Caspian and Black seas from about 5,000 to 2,300 years ago - known broadly as the Yamnaya - who typically drove wheeled horse chariots, herded livestock, buried their dead in pit graves, and spoke an early precursor Indo-European language. Another recent study suggests people from this culture almost completely transformed the genetic landscape of Europe about 5,000 years ago, where up to 90 percent of European men from some countries carry a version of the tell-tale genetic subgroup, compared to the 17.5 percent of men on the Indian sub-continent found in this latest study.
     Richards explains that it's very easy for Y-chromosome composition to change quickly, because individual men can father many children. One view is that a group of horse-riding warriors moved across India, murdering men and impregnating local women, but other explanations are available. It's possible that whole family units from the Yamnaya migrated to India, and their men either were seen as or attained higher reproductive status than locals.

Edited from LiveScience (6 July 2017)