Tools excavated from a cave in central Mexico are strong evidence that humans lived in North America at least 30,000 years ago, about 15,000 years earlier than previously thought, scientists said Wednesday.
The artifacts, including 1,900 stone tools, showed human occupation of the Chiquihuite cave at high altitude over a period of 20,000 years, they reported in two studies published in the journal Nature.
“Our results provide new evidence of the antiquity of humans in the Americas,” Ciprian Ardelean, an archaeologist at the Autonomous University of Zacatecas and lead author of one of the studies, told AFP.
“There are only a few artifacts and a couple of dates in that range,” he said, referring to radiocarbon dating results that locate the oldest samples between 33,000 and 31,000 years ago. “However, the presence is there.”
No traces of human bone or DNA were found at the site.
“Humans are likely to use this site relatively constantly, perhaps in recurrent seasonal episodes that are part of larger migration cycles,” the study concluded.
The saga of how and when Homo sapiens arrived in the Americas, the last great land mass populated by our species, is fiercely debated among experts, and the new findings will likely be discussed.
Until recently, the widely accepted story was that the first humans to set foot in the Americas crossed a land bridge from present-day Russia to Alaska some 13,500 years ago and moved south through a corridor between two massive ice sheets.
Archaeological evidence, which includes spearheads specially designed to kill mammoths and other prehistoric megafaunas, suggested that this founding population, known as the Clovis culture, spread across North America, giving rise to distinct Native American populations.
But the so-called first Clovis model has crumbled in the past two decades with the discovery of several ancient human settlements that date back two or three thousand years.
In the second study published in Nature, evidence from 42 sites in North America indicated that human presence dates back at least to a time called the Last Glacial Maximum, when ice sheets covered much of the continent, approximately 26,000 to 19,000 ago. years and immediately after.
The findings suggest that a small number of people entered the continent earlier than previously understood, some perhaps by boat along a Pacific coastal route rather than crossing the land bridge, and some died without leaving descendants.
“Clearly, people were in the Americas long before the development of Clovis technology in North America,” Gruhn, a professor emeritus of anthropology at the University of Alberta, said in comments on the new findings.
Archaeological scientist Lorena Becerra-Valdivia from the University of Oxford in England and the University of New South Wales in Australia, the lead author of the second paper, said that the continent’s populations expanded significantly from 14,700 years ago.
“These are paradigm-changing results that shape our understanding of the initial dispersal of modern humans in the Americas,” added Becerra-Valdivia.
