The researchers noted that previous studies on the subject lacked depth.
Sri Lanka's two largest ethnic groups, the Sinhalese and the Sri Lankan Tamils, who were engaged in a longstanding civil war, are genetically more similar to each other than any other South Asian population group, according to a study.
The research, published on Friday in the journal iScience and conducted jointly by Indian and Sri Lankan DNA scientists, sheds light on the historical origins of the ethnic groups in Sri Lanka as well as their social interactions.
The researchers noted that despite significant cultural and linguistic differences, the two groups intermingled in the past for several hundred years, which resulted in genetic affinity.
"Though the majority Sinhalese and the minority Sri Lankan Tamils entered into a bloody conflict during the colonial era, which continued till 2009 with the end of the civil war, mutual distrust and enmity still exist between them. However, our findings are truly intriguing," Professor Gyaneshwer Chaubey from the Department of Zoology, Banaras Hindu University (BHU), Varanasi, said.
Besides BHU, the team includes researchers from the Birbal Sahni Institute of Palaeosciences, Lucknow, Mangalore University, Mangalore, and the University of Colombo, Sri Lanka.
The researchers noted that Sri Lanka's major ethnic group is Sinhalese, which is 74.9 percent. Sri Lankan Tamils and Muslims (locally known as Moors) are 11.1 percent and 9.3 percent, respectively. Indian Tamils are the fourth population group with 4.1 percent, and a very small percentage constitute Burgher, Malay, Vedda (Adivasi), etc.
The study found that both ethnic communities-the Sinhalese and the Sri Lankan Tamils-migrated to Sri Lanka from India around 500 BC, i.e., 2,500 years ago.
"While the Sinhalese migrated to Sri Lanka from the western part of India, Sri Lankan Tamils relocated from southern India, both around the same time. There seems to be a flow of genes from both sides for hundreds of years, resulting in this genetic affinity," said R. Ranasinghe, a senior scientist at the University of Colombo.
The researchers noted that previous studies on the subject lacked depth in terms of gene mapping, and hence their findings were inconclusive.
"This is the first study that has been done on half a million genetic mutations in an individual. Due to its vast and intensive scope of work, we believe that the outcome is robust and conclusive," Chaubey said.
The team noted that normally, it has been observed that an individual's genetic profile has some commonality with his or her surroundings.
"For instance, a person who belongs to the northern part of the country shares a great deal of genetic similarity with other people from other cities in North India, but in the Sri Lankan study, we found a higher West Indian genetic component than in South India, with traces of common roots of Sinhala and Maratha," Ranasinghe said.
"Another startling aspect is the strong gene flow between Sri Lankan Tamils and Sinhalese beyond the boundary of ethnicity and language, which is unusual in a South Asian context," he added.
The team of scientists also observed that the legends say that Sinhala came from Sinhapura, which is located in India; however, scholars have disputed the correct location.
"There are two schools of thought; one says it is North-West India, whereas the other says West Bengal. This study confirmed North-West India as their homeland," Niraj Rai, another DNA scientist from the Ancient DNA Lab at the Birbal Sahni Institute of Palaeosciences, said.
The study took five years and involved, besides an extensive study and analysis, the collection of 834 DNA samples from Sri Lankan Tamils (88), Sinhalese (129), Indian Tamils from Sri Lanka (56), and Indian Tamils from India (562).