On 6th September, 2019, two ground-breaking research articles were published in the Science magazine and Cell journal:

• The formation of human populations in South and Central Asia
• An Ancient Harappan Genome Lacks Ancestry from Steppe Pastoralists or Iranian Farmers

A flurry of news articles immediately proclaimed that the “Aryan migration theory”(or the ever popular “Aryan Invasion theory”) has been debunked:

• Rakhigarhi DNA study questions Aryan invasion theory, claims author
• New DNA study debunks Aryan invasion theory
• DNA analysis of Rakhigarhi remains challenges Aryan invasion
• New DNA study challenges Aryan invasion theory

Is it time to re-write the textbooks? Let’s take a closer look.

What is the Aryan Migration Theory?

The Indo-Aryan migration theory posits an origin of Indo-Aryan speaking people outside of the Indian subcontinent. Their migration from the Central Asian steppes (thus they’re called Steppe Pastoralists) ca. 1800-1500 BCE led to a language and culture shift in the subcontinent, with the spread of Indo-Aryan languages and Vedic religious practices. A split from this population also migrated into present day Iran in the same period - bringing with them the Indo-Iranian languages.

The fledgling theory had its roots in colonial India where the British officers, who were tasked with studying local languages, noticed strong affinities between Sanskrit and other European languages. Over the years, the theory has garnered linguistic, archaeological and genetic support.

Today, the theory is used in the broader concept of Indo-European migrations to understand how one of the largest language families on the planet spread across cultures and geographic boundaries.

Aryan Invasion Theory vs. Aryan Migration Theory

The Indus Valley Civilization was one of the largest advanced civilizations of the Bronze Age, lasting from 3300 BCE to 1300 BCE. It spanned a large area in the north-western regions of South Asia.

The initial archaeological research in the Indus Valley Civilization sites revealed that it drew to an end around the same time that the Aryans migrated to India. This prompted a lot of colonial archaeologists such as Mortimer Wheeler to interpret this as an “invasion” by the Aryans that led to the downfall of the civilization.

However, no evidence to support this position was found. Rather, we see that the decline of Indus Valley Civilization had many factors including climate change. The migration of Aryan peoples into the subcontinent can thus be termed as an integration and not invasion.

Despite the fact that no informed scholar presents the theory as an “invasion”, Hindutva nationalists will present the theory as an “Aryan Invasion Theory” in order to criticize it as a racist and colonial discourse. The alternative theory favored by such Hindutva nationalists is that Hindu culture and Indo-Aryan languages originated in India and subsequently spread all over Asia and Europe (it is known as the Out-of-India theory). This view is not supported by any genetic, archaeological or linguistic evidence and is not mainstream.

The research articles

I have summarized a list of findings from both the research articles below:

Science Magazine: The formation of human populations in South and Central Asia

• After the Indus Valley Civilization’s decline, its people mixed with individuals in the southeast to form the “Ancestral South Indian” (ASI) component.
• Simultaneously, this population mixed with Steppe pastoralists who spread via Central Asia starting around 4000 years ago, to form the “Ancestral North Indian” (ANI) component.
• These movements of people spread the Indo-European languages into South Asia.

Cell Journal: An Ancient Harappan Genome Lacks Ancestry from Steppe Pastoralists or Iranian Farmers

• An ancient individual’s genome from Indus Valley Civilization was sequenced.
• The individual has a profile that is a mixture of people related to ancient Iranians (split off from Iranian plateau lineages > 12000 years ago) and Southeast Asian hunter-gatherers.
• The individual had little to none Steppe pastoralist derived ancestry. This is in contrast with the present South Asian population with more Steppe pastoralist ancestry.
• The genome also matches 11 outlier individuals in locations such as Gonur in Turkmenistan and Shahr-i-Sokhta in far-east Iran, suggesting that these were migrants from Indus Valley Civilization.

A timeline thus emerges as follows:

1. The ancient Out-of-Africa migration of Southeast Asian hunter gatherers 60000-40000 years ago populated parts of the Indian subcontinent.

2. More than 12000 years ago, a branch of ancient Iranian hunter-gatherers split off and mixed with the existing populations of South Asia.
3. This population eventually formed the basis of the Indus Valley Civilization 5000-4000 years ago, with evidence to support the indigenous development of farming.
4. Steppe pastoralists migrated to South Asia in waves beginning 4000 years ago. This explains the steppe ancestry in the current South Asian population.

The press conference by Dr. Vasant Shinde and Dr. Niraj Rai

Dr. Vasant Shinde is a former Vice Chancellor of Deccan College in Pune. Dr. Niraj Rai is Group Head, Ancient DNA Lab, Birbal Sahni Institute of Palaeosciences. They are major contributors to both the research articles discussed above.

On 6th September, 2019, they held a press conference to discuss findings of the Cell article. Surprisingly, they had a very different conclusion that does not match with the findings in both the papers. Shinde attempted to play down the Steppe migration by saying that such a migration would have left behind “material” or “cultural” markers. He also tried to demolish the old straw-man of “Aryan Invasion” by Mortimer Wheeler, by saying “The skeleton remains found in the upper part of the Citadel area of Mohenjo Daro belonged to those who died due to floods and were not massacred by Aryans…“. Rai went one step further and said that OIT (Out of India Theory) “is probably there”. Rai based this stand on the fact that there were individuals with IVC genetic makeup as outliers in Iran and Turkmenistan. However, it is widely accepted that such individuals were migrants in these regions with trade and cultural contacts.

So, why would Shinde and Rai take such a contradictory stand and show support for the fringe OIT theory? There could be a few reasons:

• They were under pressure from the current Hindutva government to promote the idea of “mool-nivasis” (sons of the soil) when it comes to the genetic make-up of the Indian people
• They have a strong bias toward the OIT theory and are being disingenuous (or even dishonest) when they came across evidence against it
• They know something that they haven’t revealed yet. This is unlikely since they’ve explained some of their thought process already in the conference.

Your guess is as good as mine. I think however that such conduct from India’s top scientists hurts the credibility of other good work being done here. Hopefully, we can move forward with less bias and be more rational in our conclusions.