Genome sequence of skeleton from Rakhigarhi of Harappan civilization raises amazing questions!

The Indus Valley Civilization (IVC) or the Harappan Civilization comprised of multiple cultural societies which lived together in large cities like Harappa (Punjab), Mohenjo-Daro (Sindh), Rakhigarhi (Haryana), Dholavira (Kutch/Gujarat), and Ganweriwala (Cholistan). Of these Rakhigarhi is one of the largest sites and was at its peak around 2800–2300 BCE.

A team led by geneticist David Reich at Harvard University and archaeologist Vasant Shinde at Deccan College in Pune have successfully isolated the DNA material and sequenced the genome for a lady’s skeleton from Rakhigarh.

Although many skeletons and remains have been found from the IVC sites, the isolating of the DNA and sequencing of the genome to do more detailed studies was very tough. A new technique has helped scientists to do this for the first time.

Although hundreds of skeletons from the Indus Valley have been uncovered, the region’s hot climate rapidly destroys the genetic material that has been instrumental in tracing the history of other early civilizations. In recent years, however, scientists have learned that the petrous bone of the inner ear contains an unusually high quantity of DNA, allowing them to locate usable genetic material even in otherwise degraded skeletons. (source)

Please download and read the study paper here – Ancient Harappan Genome.

The resulting genome of the study was compared to the outlier genome sequences from the skeletons in Iran and Turkmenistan. DNA of 11 individuals out of a set of 523 ancient DNA sequences were found to be outliers for the indigenous population at those sites. The genome of this Rakhigarhi lady closely matched DNA from 11 individuals in Iran and Turkmenistan.

First, of the 44 individuals with good-quality data we have from Gonur and Shahr-i-Sokhta, only 11 (25%) have this ancestry profile; it would be surprising to see this ancestry profile in the one individual we analyzed from Rakhigarhi if it was a migrant from regions where this ancestry profile was rare. Second, of the three individuals at Shahr-i-Sokhta who have material culture linkages to Baluchistan in South Asia, all are IVC Cline outliers, specifically pointing to movement out of South Asia (Narasimhan et al., 2019). Third, both the IVC Cline individuals and the Rakhigarhi individual have admixture from people related to present-day South Asians (ancestry deeply related to Andamanese hunter-gatherers) that is absent in the non-outlier Shahr-i-Sokhta samples and is also absent in Copper Age Turkmenistan and Uzbekistan (Narasimhan et al., 2019), implying gene flow from South Asia into Shahr-i-Sokhta and Gonur, whereas our modeling does not necessitate reverse gene flow. Based on these multiple lines of evidence, it is reasonable to conclude that individual I6113’s ancestry profile was widespread among people of the IVC at sites like Rakhigarhi, and it supports the conjecture (Narasimhan et al., 2019) that the 11 outlier individuals in the Indus Periphery Cline are migrants from the IVC living in non-IVC towns. We rename the genetic gradient represented in the combined set of 12 individuals the “IVC Cline” and then use higher-coverage individuals from this cline in lieu of I6113 to carry out fine-scale modeling of this ancestry profile. (source – emphasis added)

So there are a few important learnings from this study:

1. The IVC inhabitants had a similar genome to that of modern Indians
2. IVC inhabitants traveled to as far as Iran and Turkmenistan as far back as 3000 BC
3. There is no evidence to show, as of now, the reverse flow from Persia or Central Asia to India

What one finds most interesting is that migrants from the Indus Valley were visiting far-flung places like Iran and Turkmenistan. The three places that we are talking about are quite far off from each other.

We are looking at a civilization where the residents were moving thousands of kilometers while they traded with those regions.

To move across cold and icy mountain ranges to another land altogether and live in that culture does not necessarily come to me as a “hunter-gatherer” trait. It is far more than that. Try going on foot to Iran and you will know what that means in terms of life skills and preparation to deal with hunger, cold and heat. To go that distance requires planning and an objective-driven people, not mere hunter-gatherer attitude.

This whole categorization by the historians is very simplistic and has no relationship to the complexity of skills required to make that journey.