Seminal Discovery: Humans Arrived in Americas 15,000 Years Sooner Than Thought

SophieL

Findings in Mexico changed the timeline of human presence in North America, but anthropological questions remain.

Excavations in a cave in central Mexico uncovered tools that provide strong evidence that humans had inhabited North America at least 30,000 years ago, about 15,000 years earlier than scientists previously estimated.

  • 1,900 stone tools and other artefacts demonstrated human presence in the high-altitude Chiquihuite Cave over 20,000 years, revealed the studies in Nature.
  • "Our results provide new evidence for the antiquity of humans in the Americas," Ciprian Ardelean, archeologist at the Universidad Autonoma de Zacatecas and lead author of one of the studies.
  • No traces of human bones or DNA were discovered at the site.
  • The stone tools are unique in the Americans, revealing a “mature technology.”

The arrival of Homo sapiens in the Americas is heavily debated among experts.

  • Until recently, experts believed that humans first crossed into the Americas on a land bridge from present-day Russia to Alaska around 13,500 years ago and migrated south. This founding population, called Clovis culture, was supported by archeological evidence, including unique spear points.
  • However, the discovery of human settlements that date back two or three thousand years before Clovis debunked that model. Tool and weapon artefacts at these sites were different from Clovis technologies, indicating distinct origins.
  • The second study used radiocarbon to date samples from 42 sites in North America, finding widespread human presence “before, during and immediately after the Last Glacial Maximum,” which began 27,000 years ago.

Human presence during an earlier period coincided with the disappearance of prehistoric megafauna.

  • "Our analysis suggests that the widespread expansion of humans through North America was a key factor in the extinction of large terrestrial mammals," the second study concluded.
  • It remains a mystery “why no archaeological site of equivalent age to Chiquihuite Cave has been recognized in the continental United States,” said Gruhn, anthropology professor emerita at the University of Alberta. “With a Bering Straits entry point, the earliest people expanding south must have passed through that area.”

Read the full report.

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