‘No Genghis KhanY chromosome found in India’: Gyaneshwer Chaubey

Gyaneshwer Chaubey, professor, Gyan Lab, Cytogenetics Unit, department of zoology, Banaras Hindu University

How did the lab’s research develop after it was established?

We started the lab in 2017. I joined in October and by December we began recruiting students. Our students were interested in the population history of the Gangetic plains. That region has thousands of caste groups, and many people claim higher status within the social hierarchy. There is strict endogamy. Communities share food and cultural practices, but marriages usually take place within the same group. We began collecting samples in this region.

At the same time, we also travelled to Bangladesh and collected samples from Bangladeshi and Rohingya populations in December 2019. Soon after that the Covid-19 pandemic began.

What kind of research did you conduct during the pandemic?

During Covid-19, we could not collect new samples, so we analysed existing datasets. At that time, scientists had identified the ACE2 gene as the receptor that allows the virus to enter the human body.

Our question was whether all Indian populations had the same entry point for the virus or whether there were differences. We analysed the ACE2 gene, which is located on the X chromosome. We discovered a particular DNA segment that reduces the ability of the virus to enter the body. Nearly 60 per cent of Indians carry this segment. This led us to the concept of susceptibility. Some individuals are more susceptible to infection and others are less susceptible. Genes play an important role in this difference.

When we compared genetic patterns with Covid-19 data, we found correlations between the structure of the gene and case fatality rates in regions such as the northeast, the northwest, Maharashtra and Kerala. When we studied the Andaman population, we found very high susceptibility. We informed the government and strict measures were taken to protect those communities.

You have proposed the ‘father tongue hypothesis’. What does that mean?

Usually, we talk about the mother tongue because children spend more time with their mother and learn her language first. For example, if a European male marries an Indian female, the children generally learn the Indian language first. But while studying the origins of Austroasiatic language speakers in India, we found something different. Genetic evidence showed that this language came from southeast Asia, particularly Laos. A group of people migrated from Laos to India and married local women. In this case, the next generation learned the father’s language instead of the mother’s language. We called this the father tongue hypothesis. Once the language entered the population through the father’s line, it continued across generations.

Your research has also looked at the Mushahar community. What did you find there?

The word Mushahar literally means ‘rat eaters’. Traditionally, this community depended on rats as a food source.

When I was growing up in my village, Mushahar people lived nearby. While playing cricket, I noticed that they spoke a coded language that I could not understand. Later, a linguist told me it belonged to the Austroasiatic language family.

We collected DNA samples from the community and found that 60 to 70 per cent of their genes are associated with Austroasiatic ancestry. Over time, they moved from forests into villages, where different languages were spoken. Within a few generations, they adopted the local language, but their genetic ancestry remained the same.

Are there other communities that show similar patterns?

Yes. Central India is a melting pot of languages. Dravidian, Indo-Aryan and Austroasiatic languages are all present there.

For example, the Halba community speaks a language called Halbi, but scholars disagree on whether it belongs to the Indo-Aryan or Dravidian family. Similarly, the Kol community near the Mirzapur region and along the Uttar Pradesh–Madhya Pradesh border was once believed to speak an Austroasiatic language, but today most of them speak Indo-Aryan languages.

You have also studied the Rohingya population. What have you found?

The Rohingya study is one of our major projects because the issue is complex. Anthropological and linguistic studies present many conflicting explanations. With the help of the Bangladeshi government and collaborators, we collected samples from Cox’s Bazar. DNA analysis showed that the Rohingya have a large proportion of ancestry linked to south Asia, but they have lived in Myanmar for at least a thousand years. They also have around 20 per cent ancestry associated with populations in Myanmar.

Your team recently collected samples during the Kumbh gathering in Prayagraj. What was the aim of that study?

We received support from the local administration, residents and students. Collecting a saliva sample takes only about 10 seconds. Initially, we planned to collect detailed health information as well, but the scale of the gathering made that impossible. Instead, we collected random samples from people without asking where they came from.

In population genetics, random sampling from a mixed population can reveal the overall genetic structure. We have already analysed about 40,000 samples from India and developed a scale of Indian ancestry from 0 to 100 per cent. The idea was to see how much of India’s genetic diversity is represented in such a gathering.

Your team also collected samples from Naga sadhus. What are you trying to study there?

With the help of a doctor collaborator, we collected around 156 samples from Naga sadhus. Our question is unusual. We want to see whether there is any gene associated with becoming a Naga sadhu. Some people, when frustrated with life, may take their own lives. But these individuals choose to renounce the world. We are trying to see whether there could be any genetic factor behind that decision. It is possible we may not find anything, but it is an interesting question.

Your research has examined the ‘Genghis Khan effect’. Has anything similar been found in India?

So far, we have analysed around 12,000 samples from mainland India, although Kashmir and Ladakh still need to be studied in detail. We have not found the Genghis Khan Y chromosome in India. Globally, around 16 million people share that lineage. It is common in Central Asia, southern China and among the Hazara community in Pakistan, where about 45 per cent carry it.

This case is important because it shows how power and wealth can dramatically change population genetics. Instead of natural selection, one individual’s lineage expanded because of political dominance.

Can genetic research help address health challenges in India?

Yes. For example, one mutation in the MYBPC3 gene increases the risk of heart attack sevenfold. When we studied populations in high-altitude regions such as Ladakh and the Himalayan fringes, we found that this mutation was almost absent. This kind of information can guide medical policy. If a medicine is developed to address that mutation, it should not be used in populations where the mutation does not exist. Similarly, during Covid-19, we found that people who had already been infected produced antibody levels 20 to 30 times higher after the first vaccine dose. Based on that analysis, we suggested that those individuals might not need an immediate second dose.