New Delhi, June 27: A team of Indian researchers has used the genetic make-up of three tribes mentioned in the Ramayan to challenge the longstanding view that Indo-European speakers populated India after their root language originated in Central Asia over 6,000 years ago.

Biologist Gyaneshwar Chaubey from an Estonian research centre and his collaborators in India say their genetic analysis suggests India has not witnessed any massive influx of populations for at least 12,500 years.

The researchers analysed the genetic make-ups of the Bhils, Gonds and Kols, tribes mentioned in the Ramayan, specifically in the sections known as the Ayodhyakanda, Aranyakanda and Kiskindhakanda, and published their findings in the journal PLOS One.

"We picked these tribes because the Ramayan is among the oldest of epics from India, and we assume that the tribes mentioned in this epic would have existed beyond the timeline described in the epic," Chaubey told The Telegraph .

But some geneticists and linguists have questioned the claims made in the paper.

"The critical time estimate of 12,500 years does not appear to come from this study," said Partha Majumder, director of the National Institute of Biomedical Genomics, Kalyani, who was not associated with the paper but had himself earlier published findings about the influx of populations into India.

"Not all the inferences made in the paper can be robustly drawn from the data and the results in this study."

Linguistics specialists too have questioned the claim about the absence of large-scale influx of Indo-European speakers into the subcontinent.

"The overwhelming evidence supports the movement of people into the subcontinent," said Imtiaz Hasnain, professor of linguistics at Aligarh Muslim University.

"There is abundant evidence in the language patterns for the southward movement of populations within India, possibly triggered by the influx of Indo-European-speaking population groups from Central Asia."

Some researchers also say that anthropological, linguistic and genetic studies have "without doubt" established the arrival of Indo-European speakers into the subcontinent.

"They arrived in waves, not in one go," said Anvita Abbi, former professor at the Centre for Linguistics at the Jawaharlal Nehru University, New Delhi. "A claim that Indo-European speakers did not arrive is untenable."

Earlier genetic studies by scientists at the Centre for Cellular and Molecular Biology, Hyderabad, had shown that most modern Indians have their origins in two root populations.

These are the ancestral south Indians (ASI), not related to any population outside the subcontinent, and the ancestral north Indians (ANI), related to present-day Central Asians, Caucasians and Europeans.

The new analysis by Chaubey and his colleagues suggests that the genetic elements that mark the ASI are found at their highest levels in the Bhils, Gonds and Kols and are shared across almost all modern Indian populations.

"These genetic signatures that we call ASI appear to be the common thread connecting all Indians," Chaubey said.

"When we assemble Indian populations in the context of other world populations, they unite into one cluster."

The genetic differences observed within Indian populations, the researchers say, appear to have primarily resulted from the emergence of the caste system, environmental pressures and specific food habits.

The modern caste groups and the tribes appear to share a common ancestry from the initial settlement of the subcontinent between 50,000 and 60,000 years ago, Chaubey said.

The claims challenge the conventional view based on linguistic studies that most modern Indian caste populations are the descendants of the Indo-European speakers.