Double Check: Does evidence support Aryan migration theory?

Former Infosys board member T.V. Mohandas Pai in a recent tweet stirred another debate on the origins of India's current population by saying there is "hardly any evidence" for the Aryan migration theory. 

The Aryan migration theory stipulates that Steppe pastoralists from Europe or Central Asia (Aryans) migrated to the Indian subcontinent after the decline of the Indus Valley civilization.

Pai was responding to journalist and author Tony Joseph's post on research dismissing the "out-of-India model" that claims a family of languages widely spoken globally called the Indo-European languagesma originated from India and spread to Asia and Europe.

The debate was given fresh fire in September 2019 when archaeologist Dr. Vasant Shinde held a press conference with Dr. Niraj Rai from the Birbal Sahni Institute for Palaeosciences claiming that there was no evidence of migration of Aryans from Central Asia. 

The announcement was made after the publication of their paper in the scientific journal Cell titled 'An Ancient Harappan Genome Lacks Ancestry from Steppe Pastoralists or Iranian Farmers.' This publication coincided with another paper co-authored by Rai and Shinde, called 'The formation of human populations in South and Central Asia,' published in Science which analyzed the DNA of 500 people over the last 8,000 years to understand how human populations formed in Central and South Asia.

This press conference led to multiple news organizations like the The Times of India, Deccan Herald, The Week, and News 18 reporting that the Aryan migration theory had been debunked and disproved. 

What does the evidence show? 

In contradiction to Shinde's claims, the papers in Cell and Science do not claim that the Aryan migration theory has been disproved. In fact, both studies further validate the theory by showing how Indo-European languages naturally spread "into South Asia from Eastern Europe via Central Asia." 

Tony Joseph in his book 'Early Indians' describes a timeline for the various migrations that took place into India, taking into account genetic, linguistic, and archaeological data. Joseph writes 65,000 years ago, the First Indians, who form the genetic base of the current Indian population, migrated to India.

Then between 5,400 BCE and 3,700 BCE, early farmers and herders from Iran's mountainous region mixed with the First Indians, according to the book. And between 2,000 and 1,500 BCE, waves of Steppe pastoralists migrants from central Asia came into India. 

They brought Indo-European languages, a new Vedic culture, and religion. This wave of migration is popularly referred to as the Aryan migration.

Narratives on the theory in current times

In the early development days of the theory, it was proposed that the Aryans led a violent invasion into India, resulting in the decline and eventual end of the Indus Valley or Harappan civilization. This theory gradually grew out of favor as no evidence of violence or weapons was found at Harappan site remains. 

But earlier versions of the theory are still echoed by figures such as Bharatiya Janata Party (BJP) leader Dr. Subramanian Swamy who has previously called the theory "bunkum." The topic has been routinely covered by mainstream content creators, including popular YouTube channels like Beer Biceps, The Jaipur Dialogues, and Abhijit Chavda that claim in their video titles that the "Aryan invasion theory" has been debunked.

Although some of the aforementioned content might provide a holistic view on the theory, the flashy graphics and video titles enable narrative-building. 

"Ideologically-driven non-scholars who want to deny the migration usually prefer to attack a strawman called the 'Aryan invasion theory' because they think this will free them from the onerous task of dealing with the evidence that exists," Joseph told Logically Facts.

Joseph explained that the term "Aryan invasion" has not been used by scholars since the last few decades as there is not enough evidence to prove a cataclysmic and sudden invasion.

Steppe migration towards the end of the Harappans

Modern Indian DNA has various percentages of Steppe ancestry depending on factors such as caste and location. The paper in Cell showed that Harappans did not have Steppe ancestry, leading to the conclusion that Steppe migrations into India must have occurred towards the end or after the decline of the civilization. These findings give validity to the timeline for the Aryan migration.

This is confirmed by higher presence of Steppe ancestry in the so-called Indian 'upper caste' - those who spoke and had dominance over Sanskrit, the oldest Indo-European language in India.

Route of Steppe migrations Source: Joshua Jonathan/ WikimediaCommons

Tracing genetics

Modern science uses ancestry from human cells to trace genetics of populations by studying mitochondrial DNA passed from the mother to the offspring and Y-chromosomes passed down from father to son.

Using these, family trees of patrilineal and matrilineal lineages can be made, and an analysis points towards a migratory event into India between 2,000-1,500 BCE. This migration is also thought to be male-dominated, according to this article in the Journal of Human Genetics.

"Only about ten to 30 percent of matrilineal lineages in the country result from later migrations. But the picture is radically different on the Y-chromosome (DNA passed father to son) side," according to Joseph in the 'Early Indians.' He writes that over 60 percent of patrilineal DNA in modern Indian males results from later migrations and not from the first Indians. 

Linguistic evidence 

The Indo-European languages are a family of languages widely spoken in the Americas, Europe, and western and southern Asia. They include far-ranging languages like English, German, Greek, Sanskrit, and Bengali. All modern Indo-European languages originated from a common ancestor language called the Proto-Indo-European language.

The similarities in the vocabulary of these languages are very striking. Mātṛ́ in Sanskrit is mother in English, bʰrā́tṛ in Sanskrit is brother in English, and so on. This similarity was noticed by European scholars as early as the 16th century. 

Genetics and linguistics go hand in hand in helping to decipher the migratory patterns of ancient humans. This is where the papers in Cell and Science contradict Shinde's claims.

The paper published in Cell says, "A natural route for Indo-European languages to have spread into South Asia is from Eastern Europe via Central Asia, a chain of transmission that did occur has been documented in detail with ancient DNA." 

Similarly, the paper in Science says: "We reveal a parallel series of events leading to the spread of Steppe ancestry to South Asia, thereby documenting movements of people that were likely conduits for the spread of Indo-European languages."

Both clearly indicate that Indo-European languages most likely originated outside of India and were brought in by Aryan migrants. A Scroll article also traced how Sanskrit was recorded in Syria before India. While the Harappan script remains undeciphered, evidence suggests that the Harappans spoke a proto-Dravidian language, from which languages spoken in South India descend. 

The scholarly disagreement

Both Shinde and Rai support the "out-of-India" theory. Shinde says that there has been no major migration into India in the last 9,000 years, and that there is a cultural and linguistic continuity between the Harappan civilization and modern India. 

Shinde also opines that the Harappans were the originators of the Vedic culture – not the Steppe pastoralists – and spoke a form of early Sanskrit. Rai, however, disagrees with Shinde's view that the Harappans were Vedic people. 

But several of Shinde's co-authors in the Cell and Science papers have disagreed. Nick Patterson, one of the scientists involved in sequencing the Neanderthal genome in 2010 and a co-author, told Scroll that he disagrees that the Harappan people spoke an Indo-European language. 

In an interview with The Economic Times, American geneticist David Reich, also a co-author on both studies, made it clear that the findings show a foreign origin of Indo-European languages. He said, "Our study is not ambiguous on this topic."

Co-author of the Science study Vagheesh Narasimhan from the genetics department at Harvard Medical School told Scroll that Shinde's proposition that Harappans and Vedic people were the same "makes jumps that I am not comfortable with."

Joseph told Logically Facts that Shinde's lead-authored paper clearly states the natural route for Indo-European languages to have spread into South Asia is from Eastern Europe via Central Asia in the first half of the second millennium BCE, and a chain of transmission did occur.

"So if anyone at all were to deny that a migration from the Central Asian Steppes brought Indo-European languages to India, you have to confront them and ask them, 'Please tell me, what does this (evidence mentioned above) mean then?" Joseph said.

Shinde recants earlier findings?

Logically Facts spoke to Shinde and asked why such a disagreement exists between scholars. He said, "I differ (from my colleagues) because I'm an archeologist, and archeological evidence is very strong. Niraj Rai and David Reich are pure scientists and not archaeologists." 

This is in stark contrast to American anthropologist David Anthony who in his book 'The Horse, the Wheel, and Language' has described, in the words of Joseph, "surprising evidence of the connection between the archeological evidence in the Steppe and the myths of Indians and Iranians."

On his own papers concluding that the Indo-European languages came to India from Eastern Europe Shinde said, "We had gone with the contemporary views of the scholars at that time. But later I started synthesizing archeological sources and we did not find any strong evidence. I disagree with this line now."

He said his claims of the Indian origins of Indo-European language were based on a "hunch" and that he was making a logical argument, not a scientific one. Shinde believes that the Steppe ancestry that Indians show today is due to "some intermixing" with foreign populations and not due to migrations. 

Why the opposition?

In a now-famous incident described by Reich he revealed how his Indian colleagues threatened to shut down their 2009 research project if the term' West Eurasian' was used to describe one of the population groups from which most Indians today descend. This disagreement led to renaming the group as 'Ancestral North Indian.'

"Hindustan must be looked upon both as a fatherland (pitribhu) and a holyland (punyabhu). Muslims and Christians cannot be incorporated into Hindutva because their holyland is in far off Arabia or Palestine. Their names and outlook smack of a foreign origin. Their love is divided", wrote Vinayak Savarkar, a popular Hindutva figure with significant political and ideological influence on the BJP. 

BJP's parent organization Rashtriya Swayamsevak Sangh's (RSS) chief Mohan Bhagwat said, "DNA of Indians has been same for over 40,000 years."

If the Steppe migrations were the source of Indo-European languages and Vedic culture in India, then Savarkar's point of a Hindu holyland becomes moot. This challenges the central premise of Hindutva i.e., an indigenous origin of Vedic culture and beliefs, which may contribute to such stark opposition to the Aryan migration.

According to Harvard University Sanskrit professor Michael Witzel the 'out-of-India' narrative is a "revisionist project" which is a "political undertaking for the purpose of 'nation building.'"

(Edited by Ilma Hasan)