Acheulian stone tools, dating back to about 1.51 million years ago, have been discovered at Attirampakkam in the Kortallayar River Basin, about 60 km northwest of Chennai.
Researchers from the Chennai-based Sharma Centre for Heritage Education made the discovery, which is being published on Friday in the journal, Science.
The discovery indicates that early humans (hominins), using the tools, lived in India much earlier than previously estimated (0.6 million-0.5 million years). The tools are much older than those found in Europe.
The discovery clearly overturns the earlier assumption that the technology to produce bifacial tools appeared in South Asia at almost the same time as they did in Europe.
Acheulian tools, having their origin in Africa about 1.51 million years ago, are found in several countries in South Asia, including India, Nepal, and Pakistan.
“We need more evidence from more sites in India to know more about early human migration and dispersal [outside Africa],” said Shanti Pappu, director of the project and secretary of the Sharma Centre for Heritage Education.
Ms. Pappu is the lead author of the paper published in Science. “The tools are found in many parts of north Chennai and other places in India,” she said.
More than hundreds of different artefacts have been discovered from the Attirampakkam site. The most common ones are hand-axes, cleavers and small flakes. The stone axes are elongated teardrop or ovate-shaped with bifacial symmetry.
Unlike the hand-axes, the cleavers have broad cutting edges.
“The tools must have been used for butchering and skinning of animals and [probably] for exploiting plant resources like roots and tubers. But we are not sure about it,” Ms. Pappu said.
Ms. Pappu and her colleague and co-author of the paper, Kumar Akhilesh, have been working on the project for nearly 10 years to understand the site in terms of its archaeology and geomorphology.
“It is only after understanding the archaeology [of the site] did we start dating the tools,” she said. The dating was carried out in France by French co-authors.
The Acheulian artefacts were found at 1-9 metres depth in thick layers of clay that were deposited by a low-energy fluvial system.
“The tools are fresh [with little abrasion] and hence in situ in nature,” Ms. Pappu said.
Two different kinds of measurements were undertaken to determine the age of the artefacts.