Until recently, if you asked most experts when the first human beings arrived and settled in North America, you’d get an answer along the lines of 13,500 years ago.
But over the last few years, evidence has been mounting that humans arrived at the continent earlier. And now a massive discovery of hundreds of thousands of stone tools suggest we might have to push the date of human settlement back by at least 2,500 years.
Artefacts recently uncovered at a dig called the Gault site in Texas appear to predate by thousands of years one of the oldest and best studied collections of relics we have, named Clovis after the spot where the first group of tools was found in the 1920s, in Clovis, New Mexico.
Since the initial discovery, stone tools dating to the Clovis period have been uncovered in various other places across North and South America, but the new find adds to the growing body of evidence that people arrived on this continent long before then.
“These projectile points are unique,” says one of the researchers, Thomas Williams from Texas State University. “We haven’t found anything else like them.”
“Combine that with the ages and the fact that it underlies a Clovis component and the Gault site provides a fantastic opportunity to study the earliest human occupants in the Americas.”
Williams and his team have uncovered around 150,000 stones modified by the hands of humans at the Gault dig, which is around 64 kilometres (40 miles) north of Austin, analysing close to 200 of them. They would have been used as blades, engraving tools, scrapers, and more.
Some of these objects cloud date as far back as 20,000 years, according to the researchers, and look to be at least 16,000 years old – that’s based on an optically stimulated luminescence process, where exposing artefacts to light and measuring the emitted energy can determine when those artefacts last saw sunlight.
Add the dating to the techniques used to make these tools, which seem to be different from the various Clovis finds, and it looks as though we might have to find “a more elaborate framework” for how civilisation begin in this part of the world, the team writes.
This isn’t the first occasion that the Clovis timeline has been called into question, and the some researchers are now moving towards the idea that people were living in the Americas much earlier.
All kinds of clues – like how humans might have travelled from Asia – are being reassessed.
This particular part of the world would have appealed as a place to settle – it would have offered plenty of wild springs for feeding people and animals, as well as an abundance of flinty outcrops for fashioning tools like these.
Indeed the site has a long history, and the researchers have previously found tools matching the date and design of previous Clovis finds at the dig too.
All the signs from the Gault dig seem to suggest that the tool-making technology of the Clovis period spread across a population that was already established and indigenous, rather than one that had just arrived, the researchers conclude.
So it looks as if we have a new page of history to write, and an earlier starting date for humans in North America – at least until the next discovery.
The research has been published in Science Advances.