The items are dated to 26,000 years ago:
For most of the 20th century archaeologists generally agreed that humans who had crossed the Beringia land bridge from Siberia to North America only ventured further into the continent only when retreating ice sheets opened a migration corridor, about 13,000 years ago. But a few decades ago, researchers began discovering sites across the Americas that were older, pushing back the first Americans’ arrival by a few thousand years. Now, the authors of a new study at Mexico’s Chiquihuite cave suggest that human history in the Americas may be twice that long. Put forth by Ciprian Ardelean, an archaeologist at the Autonomous University of Zacatecas (Mexico), and his colleagues, the new paper suggests people were living in central Mexico at least 26,500 years ago.
Brian Handwerk, “Discovery in Mexican Cave May Drastically Change the Known Timeline of Humans’ Arrival to the Americas” at Smithsonian Magazine
Here’s the paper at Nature. (open access, for now)
But—also at Nature— some have come forward to say that they are not really artifacts.
The team makes a good case for ancient human occupation, says François Lanoë, an archaeologist and anthropologist at the University of Arizona in Tucson. But he adds that data from caves are “notoriously troublesome” to interpret. Stone tools might have been shifted into deeper layers by geological or biological activity — perhaps moved by burrowing animals — making them seem older than they really are.
That’s assuming they really are stone tools. “If an artefact is a stone tool, you see numerous chips removed from the edge,” says Rademaker. He sees no clear evidence of this in the images in the paper — a point echoed by archaeologist Ben Potter at Liaocheng University in China.
Colin Barras, “Controversial cave discoveries suggest humans reached Americas much earlier than thought” at Nature
One suggestion is that the misshapen tools were made by novices. We likely need more discoveries to tell.