Map of Indo-European migrations. Image by Joshua Jonathan via Wikimedia Commons. CC BY SA 4.0 Indo-Aryan migration theory, a controversy for the ages, is fueling discussions once more in India after an article published in The Hindu newspaper highlighted the genetic evidence that the Indo-Aryan peoples came from Central Asia and Europe to South Asia. Indo-Aryan peoples are an ethonolinguistic group of people that speak diverse Indo-Aryan languages and currently live predominantly in the South Asian region. The population of the modern descendants of this group is more than 1 billion, or a seventh of world's population. There has been a long tug-of-war between those who are for and against the theory that Indo-Aryans arrived to India from outside. Among opponents of the theory in India are Hindu nationalists — who sometimes cast it as a product of colonialism designed to denigrate India — as well as some researchers. The alternative theory proposed by opponents based on Rigveda, one of the oldest religious sculptures of Hinduism, suggests that the Aryans were indigenous to the Indian subcontinent. The idea of a pure Aryan race and the social division that many Hindu scriptures recommend based on one's race has pushed the conflict even further. Mainstream researchers tend to reject this theory on the basis of linguistic and genetic studies. Instead, they say evidence points to Indo-Aryans and Iranians originating from the Proto-Indo-Iranians. After this split during the period 1800-1600 BCE, the latter group was settled around Iran while the former migrated to Anatolia (most of modern-day Turkey), Pakistan, northern India, and Nepal. The classic Indo-Aryan models attempt to explain how migrations would have happened around 1500 BCE from Central Asia and Eastern Europe to South Asia and Anatolia, which possibly brought the ancestors of the Indo-Aryan peoples and their language Sanskrit to India. A detailed article published on June 16 in The Hindu, titled “How Genetics Is Settling the Aryan Migration Debate”, touches upon many other societal aspects linked to the hypothesis, such as the patriarchal social structure in India and how the Sanskrit language came to the Indian subcontinent along with the Aryans. ‘Aryan’ migration into India around 2000 BC is no longer a theory. A flood of DNA data settles the debate. My piecehttps://t.co/ZnG7ZNv0Mc — Tony Joseph (@tjoseph0010) June 17, 2017 The article cites multiple instances of research carried out in different countries, both approving and disavowing the theory. One citation is of a recent piece of research done by 16 scientists that led to the publication of a peer-reviewed journal paper titled “A Genetic Chronology for the Indian Subcontinent Points to Heavily Sex-Biased Dispersals” published in the journal “BMC Evolutionary Biology”: In particular, genetic influx from Central Asia in the Bronze Age was strongly male-driven, consistent with the patriarchal, patrilocal and patrilineal social structure attributed to the inferred pastoralist early Indo-European society. This was part of a much wider process of Indo-European expansion, with an ultimate source in the Pontic-Caspian region, which carried closely related Y-chromosome lineages, a smaller fraction of autosomalgenome-wide variation and an even smaller fraction of mitogenomes across a vast swathe of Eurasia between 5and 3.5 ka. Harvard Professor David Reich, who has been working for a long time on this subject favoring the Indo-Aryan migration theories, is also mentioned. In 2009, he published the paper “Reconstructing Indian Population History“, and later in 2016 in an interview highlighted the mixed races of the Indian subcontinent: In the beginning of 2007, we started studying at the whole genome level, the whole organism level, the DNA from initially twenty-five diverse Indian populations. It’s now more than 200 that we’ve studied. We picked these populations to be as diverse as possible, capturing the linguistic diversity of India. […] […] the great majority of Indian groups today are descended from a mixture of basically just two ancestral populations, one which we call the ancient ancestral North Indian and one which we call the ancestral South Indian. Everybody is mixed in India without exception. Even the most isolated groups, which are hunter-gatherers living in the forest or isolated places, everybody is mixed with at least 20 percent of each of these ancestries. Scheme of Indo-European migrations from c. 4000 to 1000 BCE according to the Kurgan hypothesis. Image via Wikimedia Commons by DBachmann.