Genomic Study: Indian Rors Have Roots in West Eurasia

The geographic distribution and sampling locations of newly reported modern samples from Northwest India.
The geographic distribution and sampling locations of newly reported modern samples from Northwest India. An inset shows a map of Vedic India. Dots denote the samples studied, and green color indicates samples from published literature.

A new genomic study highlights the closeness of the Ror and Jat Indian population groups to populations residing west of India, including modern Europe. The study also suggests that the genetic heterogeneity of the contemporary Indus population possibly originates from the ancient Indus Valley Civilization period.

The Indus Valley Civilization was among the greatest early civilizations, alongside those in ancient Egypt and Mesopotamia. It extended across present-day Pakistan, deep into Northwestern India, and had major settlements established on the plains between the Indus and the Ganges basin.

Archaeologists consider the settlements of Mohenjo-daro, Harappa, Dholavira, Ganeriwala, and Rakhigarhi to be early cities of the Indus civilization. Harappa was such a rich discovery that the Indus Valley Civilization is also called the Harappan civilization. The Indus Valley has been the gateway to South Asia since ancient times. The civilization flourished in the Bronze Age during 3300–1300 BCE.

The study used DNA data from four Northwest Indian population groups — Ror, Gujjar, Jat, and Kamboj — whose long-term existence in the Indus Valley region can be traced back to the early Vedic scriptures. Previously published data on the Khatri community of Punjab was also used for the analysis. The study compared the newly generated data with the DNA data of the present-day global population groups and the ancient DNA data from groups such as West Eurasians.

Ancestral North Indians and South Indians

Previous genetic studies have shown that most Indians are descendants of two ancient population groups: ancestral North Indians, who probably migrated to the subcontinent from the Middle East, Central Asia, and Europe; and Ancestral South Indians (ASI), who were native to the region and had been there much longer.

None of the several thousands of Indian caste and tribal groups seemed to represent purely ANI or ASI, but a mixture of them. Still, the populations living in the northern part of India have a greater ANI component, in contrast to the southern Indian groups that have a greater ASI component.

This study has demonstrated that Rors and Jats stand out from the variation. Rors are genetically closer to populations living west of India, such as prehistorical and early historical ancient individuals from the Swat Valley near the Indus Valley. The observed genetic relationship suggested that Ror have possibly descended from the Ancestral North Indian (ANI) population. The Ror population all over India is estimated to be 750 thousand people.

“We looked at populations in Pakistan and Northwest India and tried to see what genetic differences they are showing compared to East Eurasian and West Eurasian populations. There, Ror and Jat started to stand out from the beginning. They are closer to West Eurasian populations. They represent ancient groups that may have migrated from Central Asia or the Steppe region,” explained Gyaneshwer Chaubey, professor at the Banaras Hindu University and another senior author of the published article.

A gradient map, showing the affinity of the Ror to Eurasian populations.
A gradient map, showing the affinity of the Ror to Eurasian populations. Red color indicates populations that have a high affinity with the Ror, green indicates groups that have a medium affinity, and blue indicates groups that have the least affinity with the Ror. The filled red circle shows the top 10 populations that share the highest amount of shared drift with the Ror. The star indicates the newly sampled population group, and the black star refers to the location of the Ror population.

About the study

The study analyzed 65 genome-wide sequence data from five ethnic groups of Northwest India together with more than 2500 modern and ancient genomes worldwide. The international scientific team collected samples from four modern ethnic groups inhabiting the Harappan Civilization and generated high-resolution genetic data that includes 45 genome-wide sequences and uniparental (Y-chromosome and mtDNA) data for 248 individuals.

How is this important and how is this different from the previous studies? While most of the genetic studies from Northwest India have been focusing on uniparental data that is used to trace either paternal ancestry (Y chromosome) or maternal ancestry (mtDNA), this study is mainly based on the biparental genome data (ancestry contribution from both parents), and that gives a much clearer picture altogether.

 “This exclusive work was the concerted effort of an international team comprised of 17 researchers from 10 institutes across the world and the anonymous sample donors from Northwest Indian ethnic groups. All four ethnic groups that participated in the study are genetically close to the ancient individuals of Northern India,” says Dr. Mait Metspalu, the senior author and Director of the Institute of Genomics at the University of Tartu. “This became clear when we compared new genomic data with the ancient DNA from South Asian individuals.”

This study is the first comprehensive genetic study of the modern Harappan region. “Extensive studies on the Harappan and adjoining populations are essential for a comprehensive reconstruction of the demographic and ethnolinguistic history of Eurasia,” says Prof. Richard Villems, another senior author of the study.

Ajai K. Pathak
Photo from a private collection

Ajai K. Pathak is the lead author of the study and researcher at the Estonian Biocentre-Institute of Genomics, University of Tartu.

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