The research in question was published this week in Science, and gives us a new lens into the mysterious Indus Valley (or Harappan) Civilization. This civilization, which started some time around 3,300 B.C.E. and lasted for a good two thousand years, flourished in what is now the western part of India and eastern part of Pakistan, producing massive cities, temples, a distinctive form of pottery, work in tin, bronze, lead, and copper, and a mysterious script that no one has been able to decipher (in fact, some linguists don't even believe it's a written language -- possibly just a set of non-linguistic symbols).
A Harappan seal with an example of the Indus Valley script [Image licensed under the Creative Commons PHGCOM IndusValleySeals.JPG, Indus seal impression, CC BY-SA 3.0]
Considering the extent of the artifacts and archaeological sites the civilization left behind, it's amazing how little we know for sure about them. Their affiliations to other groups who were around at the same time (especially in the Middle East), what language they spoke, what religion they practiced -- all are inferences based on relatively scanty evidence.
This latest research adds a significant piece to what we know for sure about the mysterious Harappans. The researchers who conducted it, a team made up of scientists from Washington University, Harvard Medical School, and the University of Vienna, looked at DNA extracted from 523 skeletons in the region dating all the way back to twelve thousand years ago. The scientists were trying to shed light on two questions. First, where did the Indus Valley Civilization's agricultural knowhow come from -- was it a local invention/innovation, or was it brought into a previous hunter-gatherer society by an influx of migrants? And second, what is the origin of the languages spoken in the region then and now?
The answer to the first question seems to be that Harappans' agriculture was an innovation of their own. The researchers found traces of DNA from contemporaneous farming cultures no nearer than Iran, and no evidence that they got any further than that. So it seems like the Indus Valley transition from hunters to farmers was something they figured out for themselves.
What the research uncovered vis-à-vis the second question was that there was a DNA signature from European hunter-gatherers, but not as big as expected. The usual linguistic model is that when there's a major language shift, it's usually caused by a large influx of migrants (consider the shifts from Native languages to English in Australia and the Americas). Here, there was not nearly the amount of European and Middle Eastern DNA to explain the shift to an Indo-European language; the Eurasians who showed up there, the Yamnaya people, were apparently present in fairly small numbers. What's fascinating, though, is that Yamnaya DNA is disproportionally present in modern-day Indians of the highest social classes -- since social class has traditionally been hereditary in Indian culture, the surmise is that the Indo-European speaking Yamnaya were in charge, and their language ended up superseding (or at least strongly influencing) the language(s) spoken at the time.
It's kind of analogous to the influence Norman French had on Old English in the years after the Norman Invasion in 1066 C. E. Most of our terms that have to do with governance come from Latin via French, while a lot of the basic vocabulary (pronouns, prepositions, and so on) are from the original Germanic language. Even more interesting is that the Norman Invasion left pairs of parallel words associated with food -- the one used for the animal as it's found on the farm is from the Old English peasants who raised them, and the one for the meat as it's seen on the table from Norman French aristocracy who only came in contact with the animal after it was cooked. (Thus cow/beef, sheep/mutton, pig/pork, chicken/poultry, and so on.) As the Indo-European influx into India happened five centuries earlier, you have to wonder if those kinds of word pairs existed for while there, too, eventually being swamped by the higher-prestige Indo-European verbiage.
So this research gives us one more piece of the puzzle regarding a group of people about whom we've known relatively little, despite their being ancestral to the vast majority of the population on the Indian Subcontinent. And, of course, this is nowhere near the last word on the subject. We'll continue to uncover more, and refine our understanding of the Harappans -- a civilization that has been gone for almost three thousand years.
This week's Skeptophilia book recommendation is pure fun: science historian James Burke's Circles: Fifty Round Trips Through History, Technology, Science, and Culture. Burke made a name for himself with his brilliant show Connections, where he showed how one thing leads to another in discoveries, and sometimes two seemingly unconnected events can have a causal link (my favorite one is his episode about how the invention of the loom led to the invention of the computer).
In Circles, he takes us through fifty examples of connections that run in a loop -- jumping from one person or event to the next in his signature whimsical fashion, and somehow ending up in the end right back where he started. His writing (and his films) always have an air of magic to me. They're like watching a master conjuror create an illusion, and seeing what he's done with only the vaguest sense of how he pulled it off.
So if you're an aficionado of curiosities of the history of science, get Circles. You won't be disappointed.
[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]