Genetics is about to answer a question that has vexed historians for a century. The author examines the range of possible answers

Who built the Indus Valley civilisation? There are few questions more fundamental to our understanding of Indian history than this. On the answer to it hang many details of the country’s past: How did we come to be as we are — culturally, ethnically and linguistically? And what explains the way we are spread out geographically in the subcontinent?

Although this question has always been asked, the correct answer to it has proved resistant to the wiles and charms of historians, archaeologists, linguists and philologists for nearly a century, ever since Harappa and Mohenjo-daro were discovered in the 1920s. The fault doesn’t lie with the remarkable men and women who built what was easily the largest civilisation of their time. They had a script of their own and they left behind enough of their writings on tablets, seals, tools, pottery, and ornaments. But we haven’t managed to decipher it yet. So we don’t know who they were, where they came from, what language they spoke, what kind of social organisation or rulers they had, or even what their names were. Perhaps the only thing we know about their identity is that their trading partners in West Asia referred to their land as “Meluhha.”


[Rakhigarhi] was excavated and the skeletons were recovered in the beginning of 2014 by a team of archaeologists led by Vasant Shinde, Vice Chancellor of Deccan College, Pune. For the 61-year-old Shinde, this project is the culmination of a long and distinguished career in archaeology that has seen him lead excavations at important Harappan and other sites across the country. But Rakhigarhi is a project with a difference

In the three-and-a-half years since its excavation, Professor Shinde has brought together scientists from Indian and international institutions like the Centre for Cellular and Molecular Biology, Hyderabad (CCMB), Harvard Medical School, Seoul National University, and the University of Cambridge to work on different parts of the project, including extracting and analysing DNA from these ancient people, reconstructing their faces, and studying the remains of their habitation to understand their daily habits and ways of life.

The DNA analysis will also help figure out their height, body features, and even the colour of their eyes. In other words, we will know, rather intimately, and with a fair degree of certainty, who lived in the Indus Valley city of Rakhigarhi. It is in that sense that the Rakhigarhi ancient DNA project is unlike any other archaeological excavation that has been done in India. As Professor Shinde says: “We may have excavated a lot of burials, structures, pottery and seals. But what is new in that?”


Scenario 1: The Harappans as Vedic Aryans

In the ancient DNA from Rakhigarhi, scientists identify R1a, one of the hundreds of Y-DNA haplogroups (or male lineages that are passed on from fathers to sons). They also identify H2b — one of the hundreds of mt-DNA haplogroups (or female lineages that are passed on from mothers to daughters) — that has often been found in proximity to R1a.

There is no reason whatsoever to think that this would be the research finding, but if it is, it would cause a global convulsion in the fields of population genetics, history and linguistics. It would also cause great cheer among the advocates of the theory, which says that the Indus Valley civilisation was Vedic Aryan.


Scenario 2: The Harappans as West Asian migrants who may have brought the Dravidian languages to India

Scientists discover Y-DNA haplogroups J2 and L1a among the Rakhigarhi residents, along with mt-DNA haplogroups such as HV, K1 and T1. All these haplogroups are often associated with the origins and spread of agriculture and urbanisation in the earliest cradle of human civilisation, the Fertile Crescent in West Asia. This is a crescent-shaped region that would cover parts of today’s Iraq, Iran, Syria, Egypt, Turkey and Israel, among others. A finding such as this would not cause a major upset to any existing understanding of Asian history, but it would disprove the theory that the Indus civilisation was built by Vedic Aryans. This is because the non-discovery of R1a and the discovery of haplogroups with West Asian affinities would suggest that when the Indus Valley civilisation was thriving, Indo-European language speakers were not present on location.

Who would be cheered to hear such a result, though? That is hard to answer. One could say that the advocates of Dravidian language speakers would be, because there are grounds to think that the migrants from West Asia may have spoken a language or languages closely related to today’s Tamil, Telugu, Kannada, and so on. But the difficulty is that for the Dravidian partisans to cheer this result, they would also have to accept the fact that they too were migrants to India, much like the Sanskrit or proto-Sanskrit-speaking Aryans who arrived many millennia later.


Scenario 3: The original settlers of India as Harappans

Scientists discover Y-DNA haplogroup H and mt-DNA haplogroups M2 and M36 in the Rakhigrahi ancient DNA. All these haplogroups are indisputably autochthonous, or indigenous. In other words, they are descendant lineages of the original OOA migrants. These lineages are spread far and wide across India today, though they vary significantly in their distribution. Female mt-DNA haplogroups that are descended from the OOA migrants dominate the Indian population with a frequency of 70-80% today, while Y-DNA lineages of the same descent are present at a far lower percentage, of around 10-40%, depending on the population group. This asymmetry is not necessarily surprising — male lineages die out and get replaced at a faster rate than female lineages because of the male-biased nature of human conflicts and wars, at least from the Neolithic period onwards.


Scenario 4: The Mundas in the Indus Valley

Scientists discover Y-DNA haplogroup O2a and mt-DNA haplogroup M4a in the Rakhigarhi ancient DNA. These haplogroups are associated with the speakers of Austro-Asiatic languages such as Mundari, Santali and Khasi. These haplogroups and related languages are also present in Southeast Asia. In India, speakers of these languages are currently found mostly in Central and East India. Even though a prominent philologist of Harvard University, Michael Witzel, has argued the case for a language close to Munda (which he calls Para-Munda) being one of the languages of the erstwhile Indus Valley, a finding of this nature will come as a surprise to most others. One inconsistency is that the agricultural backbone of the Indus Valley civilisation was barley and wheat, while the Austro-Asiatic language family is spread across regions (such as Southeast Asia) where rice is the most important cultivar. In fact, one theory is that rice cultivation was pioneered in China from where it spread to Southeast Asia and was brought to India by the Austro-Asiatic language speakers. So, if the geneticists do find haplogroups O and M4a in Rakhigarhi, some of our current understanding of Indian history may have to be revised.