What is dead may never die

Dana Nuccitelli is an environment scientist who is famous for debunking the myths peddled by climate change deniers. Five years ago, in his column in The Guardian, Nuccitelli wrote about “zombie myths". Simply put, these are denials of conclusive climate science that refuse to die no matter how many times they are debunked. Such examples are legion: “Scientists are falsifying data"; “last winter was so cold, how can the planet be warming?"; “if the climate is changing, it can also change back". These are often peddled by people who preface their “folksy" wisdom with variations of the phrase, “I’m not a scientist, but…"

I was reminded of zombie myths while reading two landmark studies on genetics that were published on 6 September. These papers, one published in Science and the other in Cell, tell a complementary tale. The Science paper is titled The Formation Of Human Populations Of South And Central Asia, by Vagheesh M. Narasimhan and others. It’s a study of the genomic make-up of the ancient DNA of 523 individuals spanning 8,000 years, primarily from Central Asia and northernmost South Asia, and provides a detailed and robust overview of ancient population movements across large parts of Asia. One of the paper’s findings, of particular interest to India and South Asia, is that pastoralists from the Central Asian steppes—in other words, the “Aryans"—did indeed spread to the subcontinent, but that migration began only in the second millennium BC, i.e. between 1500-2000 BC.

The other paper, published in Cell, focuses on the ancient DNA of one particular skeleton, over 4,000 years old and probably a woman’s, found in a Harappan cemetery from the mature Indus Valley Civilization (IVC) site of Rakhigarhi in Haryana and correlates it with that of 11 other skeletons from IVC-adjacent areas sampled in the Science study. Titled An Ancient Harappan Genome Lacks Ancestry From Steppe Pastoralists Or Iranian Farmers, the paper shares many of the same authors, including Vasant Shinde, head of the department of archaeology at Pune’s Deccan College, Narasimhan from the department of genetics, Harvard Medical School, and David Reich of the Howard Hughes Medical Institute, Harvard Medical School. The ancient genomic sequence that this study discusses establishes that Harappan DNA is present in most present-day Indians. The study finds no trace of the steppe pastoralists in the Harappan DNA.

Simply put, this means that the people of the IVC were not genetically related to the steppe pastoralists. The latter did migrate to the subcontinent carrying Indo-European languages, but that happened after the waning of the IVC, around 2000 BC. So the IVC has nothing to do with the culture of the Indo-European languages—the “Vedic" culture of the so-called Aryans. We now have a plausible model of Indo-European language speakers migrating in waves to northern India after the decline of the mature-phase IVC. The DNA findings support that hypothesis.

In a 9 September interview to The Economic Times, Reich spells this out clearly: “For the first time, we have a genetic model that fits statistically for most present-day South Asians: mixture of IVC-like people, and other (smaller contributions) from other populations for which we have genetic data," he says. It’s quite unambiguous; most Indians have a large amount of Harappan DNA, mixed with a varying amount of steppe pastoralist (Aryan) DNA that came in later. Reich says this latter number “ranges from 0-30%. People with this ancestry almost certainly spread into South Asia from the north 4,000-3,500 years ago."

This is where the zombie myths come in. Like climate science, the origin of Indians is a politicized subject, and this makes even a purely scientific finding politically fraught. Let’s look at some of the myths that have been peddled by Hindu nationalist historiography and its proponents. The main one is that a Vedic cultural civilization originated in South Asia, predating the IVC, and later moved to Central Asia and Europe. The corollary to this theory is that India has always been “Hindu"—the Harappans were Vedic Aryans. This Out of India (OOI) thesis allows culture warriors on the right to make claims about an “eternal Hindu civilization" forever tied to the subcontinent. Any attempt to fix the scientific fact that the ancestors of the Vedic pastoralists were themselves “outsiders", like many others, and that too of fairly recent vintage, basically debunks this thesis. The Cell paper says that the genetic results have “linguistic implications" and very clearly states, “(However) a natural route for Indo-European languages to have spread to South Asia is through Eastern Europe via Central Asia in the first half of the 2nd millennium BCE, a chain of transmission that did occur as has been documented in detail with ancient DNA."

But zombie myths are bound to rear their heads again, sooner or later. Although the papers are barely a week old, media pieces have already misrepresented the Cell paper to proclaim that the “Aryan Invasion Theory" has been debunked. That isn’t true, because the theory no longer exists in scholarship. But the genetic data does support what could be called the “Aryan Migration Theory". While revealing the full bouquet of India’s genetic and cultural inheritance remains a work in progress, the fact that this inheritance is multifaceted, is indisputable. However, that is unlikely to stop people from muttering, “I’m not a scientist, but…"