AsianScientist (Sep. 25, 2019) – An international team of scientists has successfully sequenced the first genome of an individual from the Harappan civilization, also called the Indus Valley Civilization (IVC). They reported their findings in the journal Cell.
The IVC, which at its height from 2600 to 1900 BCE covered a large swath of northwestern South Asia, was one of the world’s first large-scale urban societies. Roughly contemporary to ancient Egypt and the ancient civilizations of China and Mesopotamia, it traded across long distances and developed systematic town planning, elaborate drainage systems, granaries, and standardization of weights and measures.
Hot, fluctuating climates like those found in many parts of lowland South Asia are detrimental to the preservation of DNA. So despite the importance of the IVC, it has been impossible until now to sequence DNA of individuals recovered in archaeological sites located in the region.
In the present study, researchers screened 61 skeletal samples from a site in Rakhigarhi, the largest city of the IVC. A single sample showed promise: it contained a very small amount of authentic ancient DNA, which motivated the team to make more than 100 attempts to sequence the sample.
“The Harappans were one of the earliest civilizations of the ancient world and a major source of Indian culture and traditions, and yet it has been a mystery how they related both to later people as well as to their contemporaries,” said Professor Vasant Shinde, an archaeologist at Deccan College, Deemed University in Pune, India, and first author of the study.
The researchers found that the DNA belongs to an individual who lived four to five millennia ago, suggesting that modern people in India are likely to be largely descended from people of this ancient culture. The sample also offers a surprising insight into how farming began in South Asia, showing that it was not brought by large-scale movement of people from the Fertile Crescent of the Middle East where farming first arose. Instead, farming started in South Asia when local hunter-gatherers became sedentary and began practicing agriculture.
The sequencing data further revealed that the individual fits in with a set of 11 individuals from sites across Iran and Central Asia, known to be in cultural contact with the IVC. Those individuals were genetic outliers among the people at the sites in which they were found. They represent a unique mixture of ancestry related to ancient Iranians and ancestry related to Southeast Asian hunter-gatherers. Their genetic similarity to the Rakhigarhi individual makes it likely that these were migrants from the IVC.
“The insights that emerge from just this single individual demonstrate the enormous promise of ancient DNA studies of South Asia. They make it clear that future studies of much larger numbers of individuals from a variety of archaeological sites and locations have the potential to transform our understanding of the deep history of the subcontinent,” Shinde said.
The article can be found at: Shinde et al. (2019) An Ancient Harappan Genome Lacks Ancestry from Steppe Pastoralists or Iranian Farmers.
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Source: Deccan College Post Graduate and Research Institute; Photo: Vasant Shinde/Deccan College Post Graduate and Research Institute.
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