In politically sensitive study, India looks to DNA to track ancient migrations
Introduction
A hundred years ago, archaeologists discovered a sophisticated Bronze Age civilization that flourished between 5000 to 3500 years ago along the Indus River, now India and Pakistan. The discoveries, consisting of extensive fortified cities and remarkable artifacts, assisted in altering the region’s history.
Currently, geneticists in India aim to employ the DNA extracted from over 300 human bones and bone fragments collected during those excavations to shed new light on the origins of India’s population. Reported by Indian media last month, the project has “enormous value and potential” to deliver further insights into ancient ancestries and migrations in the region, according to geneticist Partha Majumder, founder of India’s National Institute of Biomedical Genomics, who is not involved in the study.
However, the project has the potential to either worsen or resolve a politically sensitive debate. For years, Hindu nationalists who aligned with India’s current government have been hesitant to accept research findings suggesting that ancient migrants from the Eurasian Steppe, which spans from China to central Europe, played an important role in the establishment of Indian society.
The Anthropological Survey of India (ASI), a 70-year-old institute under the Ministry of Culture that oversees biological remains from the colonial-era excavations, is conducting the DNA study. ASI has joined forces with the government-funded Birbal Sahni Institute of Palaeosciences, one of the two labs in India capable of isolating ancient DNA (aDNA) from bones and other tissues.
Origins and Potential Implications
According to ASI Director BV Sharma, majority of the skeletal remains were found during the excavations that took place from the 1920s to the late 1950s at Harappa, Mohenjo-Daro, and other ancient settlements of the Indus Valley.
By comparing aDNA retrieved from the bones with DNA sequences from modern people, “we hope to generate more insights on the history of Indian populations as well as information on diets, living environment, and disease,” Sharma told Science. Although researchers are already aware of the origins of India’s populations, “there are gaps in the timeline that need to be filled,” says Gyaneshwer Chaubey, a population geneticist at Banaras Hindu University who is involved in the project. For example, scientists do not know much about the people who cultivated rice along the Ganges River thousands of years ago.
Researchers aim to complete their analyses by the end of 2025, but obtaining aDNA from the bones may present challenges. As stated by Sharma, DNA degrades more rapidly in tropical climates, and previous procedures for excavating and handling bones may have exacerbated the issue. “But with today’s advanced technology, we might be able to get something more out of it,” he says. “Even if 10% or 20% of the old DNA samples can be isolated and analysed, it will be useful,” adds K Thangaraj, a senior scientist at the Centre for Cellular and Molecular Biology who is not involved in the study.
Other researchers are supportive of this initiative. They highlighted that South Asia is underrepresented in genomic studies, despite being one of the world’s most diverse populations. Majumder notes that much of the present understanding of the structure and ancestry of India’s population is derived from studying DNA from alive human beings. If modern data can be corroborated or validated by older DNA samples, it would be highly valuable. Thangaraj emphasises that the aDNA could be useful in understanding the evolution of human diseases in the region. He also observes that Indian populations are particularly susceptible to recessive or rare diseases due to higher occurrences of endogamy (the practice of marrying within clans) and ancient genomics could uncover insights on the origins of those diseases.
What the DNA reveals about the origins of the Indian people could carry political implications. Some of the bones may date back to 3800 to 3500 years ago, coinciding with the period when Yamnaya pastoralists from the steppes, previously referred to as Aryans, are believed to have migrated to India. Historians suggest that Sanskrit, a classical language of the region, originated with these immigrants. Nonetheless, many Hindu nationalists dismiss or reject this scenario, partly due to its lingering association with colonial narratives about fair-skinned Aryans dominating the region. Experts believe that the Yamnaya were nomadic herders who arrived in small waves. On the contrary, Hindu nationalists propose an opposite sequence: that Aryans were indigenous to India and eventually introduced their language and culture to Central Asia and Europe.
Conclusion
Most academics disagree with this viewpoint, but it remains popular among some Hindu nationalist supporters of India’s ruling Bharatiya Janata Party and certain Indian Media outlets. For instance, in 2019, many Indian journalists reported that a study of aDNA from a 4500-year-old skeleton of a woman who lived in the Indus Valley demonstrated there had been no “Aryan migration,” because she carried no steppe ancestry. In reality, the study simply reinforced previous evidence that the steppe migration happened later. In April, India’s government revised an established grade 12 history textbook to portray the study as undermining the steppe migration scenario.
Chaubey suggests that the new study is likely to “refine” the mainstream scientific understanding rather than overturn it. Additionally, he doubts that any genetic discoveries will put a stop to the political claims.
“Scientists are not confused,” he claims. “Politicians are.”
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