The researchers are confident that this is conclusive evidence that people lived in North America at least 30 thousand years ago, which is 15 thousand years earlier than previously thought.
An excavation report published in the journal Nature says artifacts, including 1,900 stone tools, indicate that humans have occupied Chiquihuit High Mountain Cave for 20,000 years.
No traces of human bones or DNA were found at the excavation site, which gave scientists reason to believe that humans used the site on a relatively consistent basis.
“Perhaps in recurring seasonal episodes that are part of larger migration cycles,” says Cyprian Ardelean, an archaeologist at the University of Autónoma de Zacatecas.
This is further evidence that the American continent was inhabited in ancient times.