AFRICANGLOBE – The first early humans to leave Africa did so half a million years earlier than we thought, according to an analysis of simple stone tools and three cow bones with cut marks found in Asia. But not everyone is convinced yet.
A joint Indian-French team found the artefacts on the Siwalik hills about 300 kilometres north of New Delhi, India, where tectonic activity has exposed an outcrop of bedrock dating back at least 2.6 million years.
The bones and tools were found lying on the surface, which made their dating tricky. But given that artefacts are rare in the younger rocks surrounding the outcrop, and the latest finds were preserved in the same way as those previously uncovered in the ancient bedrock, they probably eroded out of the bedrock on which they sit, the team says.
“There is no doubt regarding their origin,” says Mukesh Singh of the Society for Archaeological and Anthropological Research in India, who co-led the team that scoured the area for signs of ancient human activity between 2003 and 2015.
The team’s examination of the cut marks on bones (shown above) suggests that they were made with a stone tool. “We are absolutely confident,” says Singh. “Hominins lived in sub-Himalayan floodplains 2.6 million years ago.”
The earliest accepted evidence of early humans outside Africa so far is Homo erectus remains found at a site at Dmanisi, Georgia, that date back about 1.85 million years. Taken at face value, the new finds suggest that our Homogenus had migrated into Asia much earlier – it may even have evolved in Asia before moving into Africa.
Another possibility is that the Siwalik finds are evidence that earlier ape-like hominins in the genusAustralopithecus lived in Asia as well as Africa. But Anne Dambricourt Malassé at the Institute of Human Palaeontology in Paris – another co-head of the team – says this is unlikely because australopiths were adapted to life in trees and probably wouldn’t have undertaken long migrations across the savannahs.
Yves Coppens of the Collège de France in Paris has long favoured the idea that hominins left Africa much earlier than 2.5 million years. He says he encouraged the team to explore deposits of this age in the Siwaliks and offered advice once they had found the artefacts. “I pushed them to check and cross-check,” he says. “Everything seems to be all right.”
More Evidence Needed
But other researchers say stronger evidence is needed to back the team’s extraordinary claim.
“They’re making a huge claim here – that early humans were in Asia hundreds of thousands of years earlier than we expected,” says Michael Petraglia at the University of Oxford, who studies the early spread of humans from Africa.
He’s open to the idea in principle – and says the Siwalik hills are certainly worth archaeological investigation – but he thinks far more evidence is needed. “There is a lot to prove with respect to deposits, age of deposits, cut marks and whether these are human-manufactured tools,” Petraglia says.
It is problematic that the stone tools and bones were found on the surface rather than in a dateable rock layer, says Shannon McPherron at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who studied possible butcher marks on 3.4-million-year-old bones found at Dikika in Ethiopia. Also, proving cut marks on bones were made by hominins is a huge challenge, he says, as description and interpretation of such marks is an area of contentious debate.
This isn’t the first find that hints at a much earlier human presence outside Africa. Last year, a research team reported very early stone tools from a cave in China dated to 2.48 million years ago, which Dambricourt Malassé interprets as growing evidence for a much earlier human presence outside Africa.
But Petraglia says it’s unlikely these early reports will change the orthodox view that early humans first left Africa much later.
By: Colin Barras
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