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. CC BY SA 3.0

‘If the evidence has really changed, I will also change my view’

Audrey Truschke, assistant professor of South Asian history at Rutgers University in the US, tweeted out the article:

The linguistic evidence for the #AryanMigration theory is very strong. For those that need hard science also: https://t.co/AigrwNS4wX

— Audrey Truschke (@AudreyTruschke) June 16, 2017

Sitaram Yechury, a veteran leader of the Community Party of India, and Devdutt Pattanaik, a mythologist and writer, similarly hailed the article:

The historical evidence of Aryan migration and the confluence that India is. Brilliant piece by @tjoseph0010 https://t.co/wCZvoPY4pm

— Sitaram Yechury (@SitaramYechury) June 17, 2017

Excellent article . Scientific so will upset myth-haters. https://t.co/8xxXpIMe9e

— Devdutt Pattanaik (@devduttmyth) June 17, 2017

However, Anand Ranganathan, a consulting editor at the Indian news outlet Newslaundry.com, attacked the article in the Hindu:

A few quick points on the interesting piece on Aryan Migration published today in the Hindu. pic.twitter.com/UjaBmEdZx9

— Anand Ranganathan (@ARanganathan72) 17 de junio de 2017

Nityanand Jayaraman, a Facebook user, also pointed at the possibility of a close connection of north Indians with the people of Afghanistan and Pakistan:

Interesting article on how Yogi Adityanath and Vishnu Bhagwat may be more closely related to their brothers in Pakistan and Afghanistan than they care to acknowledge. And about India's multiculturalism.

Sanjeev Sanyal, a writer who earlier opposed the Aryan invasion theory, has written on Facebook that he would read the recently published papers and is ready to change his opinion if there is a changed evidence:

The genetic evidence on “Aryan Invasion” appears to have shifted to support a migration around 2000 BC (according to this article anyway). Have not closely followed the latest papers, will need time to read the new papers on this. If the evidence has really changed, I will also change my view. Only way to do research.

The debate on whether Indo-Aryans migrated from outside India and brought their oldest language Sanskrit to the South Asian region continues to rage and pave the way for more anthropological research on the people, cultures and languages of the region. There are over 780 languages across India which makes India one of the most linguistically diverse countries in the world. However, of these languages, only 22 enjoy constitutional protection while over 196 languages are endangered.