If science proceeds funeral by funeral, history takes the route of wildfires. And the largest wildfire of them all, one that has consumed us for the better part of a century, is the debate surrounding our roots. Who are we, where did we come from; is this land ours or are we mercenaries? While both science and history struggle to discover answers to these questions, the difference lies in the timescale. RNA World in one case, Aryan World the other.

For the victors a quill to write history with, for the vanquished the burden to peddle it. Nations weaken not because of their past but rather by how they are taught it. For more than a century Müller-putras have sold to us a theory that tries to explain who we are. It goes like this: Around 3,500 years ago, a horde of light-skinned warriors called Aryans invaded the upper reaches of Hindoostan only to percolate slowly to the badlands where they accosted the dark-skinned Dravidians. This so-called Aryan Invasion Theory, or AIT, has echoed forever and a day beyond in our history classrooms and we, the children of a coerced conscience, have lapped it up. There is an opinion – not unfounded – that AIT is nothing but magic realism, a coloniser’s fantasy that hymns n’ high culture came galloping down from the civilised world to the barbaric. The natives had to be shown their place. Run along now!

To her credit, the eminent historian Romila Thapar was among a chosen few to have denounced AIT. “Not only did the invasion not happen, the use of the word Aryan itself is erroneous.” The Aryans were a linguistically similar collection of people and not a race, wrote Prof Thapar. “They didn’t invade India, they migrated to it.”

Prof Thapar may not believe in the Aryan Invasion Theory – preferring the Aryan Migration option instead – but she has done little to oppose it, a fact that emerged from the 2005 California state schools controversy when there were found as many as 49 textbook mentions of the word “Aryan”. These included claims such as: “Around 1500 BCE, invaders called Aryans conquered northern India”…“Some historians credit the Aryans with bringing Hinduism to India.”…“The Aryans created a caste system”…“Aryan technology improved farming in India”. When some Hindu groups protested, Prof Thapar – having earlier never objected to the inclusion of such references – bitterly opposed changes to the curriculum. “We should stick to teaching the facts,” she said.

True, Prof Thapar does not believe in the Aryan Invasion – she has said so publicly. But did she ever believe in it only to adopt later the diluted version? There exists no evidence of this – in her books or in transcripts of her lectures. To be sure, the invasion-migration question is a moot one. Millennia-old human history makes us realise, time and again, that migrations are seldom non-threatening, especially when they happen across populated continents. As Prof Thapar admits in her book Early India: “Some settlements in the north-west and Punjab might have been subjected to raids and skirmishes [by the Aryans], such as are described in the Rig Veda, or for which there appears to be occasional evidence at some site, for example Kot Diji.”

Sure, invasions can be diluted. What is malignant one day can turn benign the next. Here is Prof Thapar on India’s recent past: “I do not see the medieval period as one where the Muslims are the conquerors. It was a period of creation of communities. Muslims came in various ways. They were traders, they were pastoralists, they were conquerors, they were missionaries, and they created different kinds of communities all over the subcontinent…The trauma of Mahmud of Ghazni’s raid on Somnath was never experienced at the time or even for centuries thereafter. This trauma has been appropriated from the reading of the British version of this event.”

There are historians who disagree with Prof Thapar’s diluted view of Islamic invasions, and they cite the same sources as she does – Chachnama or Rihla – sources that either describe the invasions or their immediate aftermath. Many also point out – through their writings on the annihilation of Vijayanagara, academic or narrative – that the assimilation of Islam in south India was hardly the “smooth process” Prof Thapar claims it to be.

History is not Homeopathy – it does not leave an imprint when diluted, it simply disappears. Ironically, Prof Thapar by her own admission is practicing an art that can be doubted at every step. “Even archaeological artefacts are as much subject to interpretation as textual facts,” she says. She is not alone. The acclaimed historian Ilan Pappé told BBC recently: “Sure, the History I write is influenced by my agenda and ideology, but so what!”

What, then, is to be done? Are we to reduce History to dining-table fights, at the returning mercy of wildfires – douse one, get ready for the next? Perhaps.

Perhaps not, with a little help from science. Indian historians may think otherwise but Population Genetics, a discipline still in its infancy has made immense contribution towards corroborating historical details and is as indispensable today as an archaeologist’s coco-bristled hand brush. At its base it is the study of haplogroups, a term meant to indicate a common ancestor traceable because of identical mutations in lineage DNA. These mutations, called Single Nucleotide Polymorphisms or SNPs, accumulate through the passage of time and act as “markers” to identify a specific haplotype. To make sense out of SNPs, one ideally needs a region of genome that doesn’t undergo recombination. Mitochondrial DNA or mtDNA, is one such region as is also the Y chromosome, passed down from father to son. Mitochondrial DNA does not recombine, only gathers mutations along the evolutionary timeline. Remarkably, the human egg is genetically programmed to tag any incoming sperm mitochondria with a “death-tag” protein called ubiquitin, thereby assuring its destruction. All mitochondria, therefore, are inherited exclusively from the mother’s side; the further away in time they are the more SNP mutational differences there will be. Indeed, using a calibrated molecular clock, i.e. a verifiable tool to calculate the mutational rate, one can estimate the age of divergence or coalescence (merging). To understand how population genetics has helped solve the Aryan question it is worth recounting some of its monumental discoveries beginning with, well, the beginning.

Africa is where Man began – and Woman, too, of course. No surprise, then, that both Adam and Eve, our “most recent common ancestors”, are African. Information gained from sequencing whole genomes of 69 males from nine populations has led scientists to estimate Adam’s age to be between 120,000 and 156,000 years. For Eve it is 99,000 to 148,000 years. And even though the Adams were a happy lot, it wasn’t long before curiosity got the better of them. Migrations started in earnest, first briefly to Israel (90,000 years ago) and then in a major way 5000 years later to other parts of the world including India (66,000 years ago) and, following the southern route, Australia some 3000 years later. Population genetics has helped us understand the nature and timescale of these migrations, from North America to Singapore to Gujarat, besides solving some long-standing mysteries. For example, we now know that Roma gypsies migrated to central Europe exclusively from Punjab.

To return now to the question of the troublesome Aryans, Prof Thapar believes Aryan Migration happened around the time of the Rig Veda that, she concurs, resembles the Iranian sacred text Avesta – dated 1400 BC. The Iranians split into two groups one of which – the Indo-Aryans – migrated eastwards and reached India. Upon reaching India they penned the Rig Veda, a facsimile of Avesta except for a bizarre reversal of subject matter – the Avesta Gods became Rig Veda demons and vice-versa. The migration of peoples was also accompanied by migration of names and places. “The Harahvati becomes Sarasvati, quite a distance away from Afghanistan to Punjab. The Harayu becomes Sarayu from Afghanistan to UP.”

In her book, Early India, Prof Thapar accepts the theory that “Indo-Aryan speakers gradually migrated from Indo-Iranian borderlands and Afghanistan to northern India where they introduced the language. The migrations were generally not disruptive of settlements and cultures [no citation provided]”…“[The immigrants] were dissident groups that had broken away from the speakers of Old Iranian, whose language and ideas came to be encapsulated in the Avesta.”

Clearly, Prof Thapar is of the view that the migration happened after Avesta, i.e. around 1400 BC or 3,500 years ago. Unfortunately for her, science knows otherwise.

In a remarkable 2009 study published in the journal Nature, scientists were able to show that Indians can lay a worthy claim to two ancestral groups – Ancestral North Indians, ANI, and Ancestral South Indians, ASI. The ANI, Singh and co-workers discovered, were genetically close to Central Europeans or Eurasians. Interestingly, the Andaman tribe Onge were found to possess no ANI ancestry of any kind. In fact, Singh and co-workers were the first to study the origin of the Andaman and Nicobar people. The Onge, they revealed, have evolved quite independently from other human populations, untouched since their ancestors migrated from Africa 50-70,000 years ago. These findings have since been corroborated by several research groups worldwide. ANI indeed possesses a higher component of European ancestry compared to ASI even as the two groups share common genetic variants. Another extended study, that analysed as many as 1.4 million ANI and 1.6 million ASI SNPs, also reached the same conclusion, of a gene-flow from Europe to north India.

But it was the publication in 2011 of a path-breaking study that ultimately sealed the fate of the Aryan Invasion or Migration theory. Analysing 600,000 SNPs from as many as 30 ethnic groups – thereby extending the 2009 Nature ANI study through the inclusion of more European samples – Toomas Kivisild and co-workers discovered that both components of Indian ancestry, ANI and ASI, predate the Aryan Migration event by at least 9000 years. This was because the so-called k5 component, that bestows ancestry to South Asians, was found to contain no regional diversity differences; its spread across the Indian subcontinent must have happened well before 12,500 years ago (the detection limit) and not through a recent gene-flow event. In 2013 Singh and co-workers extended the Kivisild study with some acute observations, namely that the ANI and ASI populations mixed robustly between 1900 to 4200 years ago and that these two groups didn’t mix either before or after this window. The authors, by analysing genomes of 571 individuals representing 73 ethno-linguistic groups, also ruled out Eurasian gene flow during this time period, concurring with the finding of another study that such an event could not have happened before 12,500 years. Moreover, argued the scientists, 3500 years ago India was a already a densely populated region with well-established agricultural practices and therefore the Eurasian migration would have had to be immense in order to explain the fact that half the Indian population is derived from ANI. The Aryan Migration event of 1500 BCE has also been questioned based on an authoritative haplogroup U linkage study wherein scientists found an extensive and deep late-Pleistocene link between Indians and Europeans, suggesting a coalescence near the time when Asia was initially being peopled. The migration that led to the Indo-Eurasian stock, according to these scientists, happened not 3,500 years ago but rather 12,500 years or earlier. Another study, this time involving Y-DNA haplotyping, rules out substantial gene-flow from Europe to Asia at least since the mid-Holocene period, i.e. the last 6,500 years. It has also been shown that the gateway to the subcontinent, the Hindu Kush – where the earliest archaeological evidence of human remains dates back to 26,500 years before the Rig Veda – was a confluence of gene-flows in the early Neolithic period as opposed to an indigenous population.

There is one other way to corroborate that Eurasian migration happened much before the time-point vouched for by AMT proponents – skin colour. It has long been known that a single mutation, rs1426654, in the human pigmentation gene SLC24A5 accounts for the lighter skin tone of Europeans. A year ago, scientists discovered that an allele of the rs1426654 mutation was shared among many South Asian and Western Eurasian populations. The coalescence was calculated to be 22000-28000 years ago, with the frequency of occurrence of this mutation – called the allele frequency – found to be significantly higher in the ANI compared to the ASI.

The verdict of population genetics is clear, and profound, as pointed out subsequently by the lead author of the Nature study Dr Lalji Singh himself: “There is no genetic evidence that Indo-Aryans invaded or migrated to India. It is high time we re-write India’s prehistory based on scientific evidence.”

Prof Thapar, though, is dismissive of the overwhelming scientific evidence that negates the Aryan Migration event. “The DNA results from various sources,” she says, “have been so confused and contradictory that it is difficult for me to accept what any of them say. None of them are social historians nor do they consult historians and sociologists before they make their categories, hence the confusion.”

The force of science is brute yet unassuming. Yes, Galileo had to apologise but he must have done so with a smirk. Popular opinion matters little when the thrill of eureka has already been consumed and relished by the discoverer. One learns to move on. In the 1950s, two theories that explained to us the universe – the Steady State and the Big Bang – garnered equal wrestling time. But then over the ensuing decades it was the Big Bang that came through unscathed, with the result that only those who had a hand in proposing the Steady State now believe in it.

Time waits for no one, least of all junked theories. Scientists, having pointed out that the Müllerian Aryan Invasion – or the Romilian Aryan Migration – never happened, have returned to their garages. Historians are still at the dining table. C’est la vie.

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 Author’s note: Some of the statements and quotes have been abridged for want of space.