Ancient human footprints preserved in the ground across the White Sands National Park in New Mexico are astonishingly old, scientists reported Thursday, dating back about 23,000 years to the ice age.
The results, if they hold up to scrutiny, would rejuvenate the scientific debate about how humans first spread across the Americas, implying that they did so at a time when massive glaciers covered much of their path.
Researchers who have argued for such an early arrival hailed the new study as firm proof.
“I think this is probably the biggest discovery about the peopling of America in a hundred years,” said Ciprian Ardelean, an archaeologist at Autonomous University of Zacatecas in Mexico who was not involved in the work. “I don’t know what gods they prayed to, but this is a dream find.”
For decades, many archaeologists have maintained that humans spread across North and South America only at the end of the last ice age. They pointed to the oldest known tools, including spear tips, scrapers and needles, dating back about 13,000 years. The technology was known as Clovis, named for the New Mexico town, where some of these first instruments came to light.
The age of the Clovis tools lined up neatly with the retreat of the glaciers. That alignment bolstered a scenario in which Siberian hunter-gatherers moved into Alaska during the ice age, where they lived for generations until ice-free corridors opened and allowed them to expand southward.