London: A team of archaeologists has claimed that they have found 22,000-year-old stone tools at a site in Brazil.
The finding, according to them, suggests humans lived in South America at the height of the last ice age, thousands of years earlier than we thought, according to New Scientist.
But other archaeologists are disputing the claim.
Christelle Lahaye of Michel de Montaigne Bordeaux 3 University in France and colleagues found 113 stone tools while excavating a rock shelter in north-east Brazil.
The team dated the sediments in which the tools were buried using a technique that determines when the sediments were last exposed to light. Some tools were buried 22,000 years ago - thousands of years earlier than any known human colonisation of the Americas.
For decades, archaeologists thought that the Clovis people were the first to enter the Americas, 13,000 years ago. But since the 1980s evidence has accumulated for an earlier colonisation, at least 15,000 years ago.
The dating tests suggest humans could have been in Brazil 22,000 years ago, said Ann Wintle at the University of Cambridge.
But John McNabb of the University of Southampton, UK, pointed out that rock shelters are difficult to interpret.
Stones falling from above can break, making them look like human-made tools. So, McNabb calls the evidence "suggestive but unproven".
Lahaye insisted that the falling-stone scenario is unlikely in this case because the tools are made of a rock not present at the site.
"They come from at least 15 kilometres away," she said.