The first Homo sapiens appear to have reached the Americas at least 20,000 years ago.
A new radiocarbon-dating study offers further confirmation of the antiquity of a series of fossilized footprints in New Mexico that are rewriting the history of human settlement in the Americas.
The analysis, published in Science Advances, confirms that the footprints first revealed in 2021 and widely discussed among anthropologists are between 20,700 and 22,400 years old.
These findings align with two earlier studies that concluded the fossil tracks are around 22,000 years old placing them at the height of the last Ice Age.
The footprints are at least 7,000 years older than the next earliest accepted evidence of human presence in the Americas.
The prevailing theory has long held that the first settlers reached the continent via a land bridge that once connected Asia and Alaska.
Dozens of human footprints at White Sands, New Mexico, were found in a layer of dried mud near a river that once flowed into ancient Lake Otero.
The tracks tell the story of a group of people who collected water from the lake, hunted giant ground sloths and other prehistoric animals, and let their children play along the shore.
Evidence in the Mud
The first study on the footprints, published in Science in 2021, used radiocarbon dating on tiny seeds of an aquatic plant found embedded in the dried mud.
The study caused a sensation but also skepticism, as the seeds could theoretically have absorbed carbon-14 from ancient sediments that somehow washed into the lake.
The same research team returned in 2023 with a new study, this time dating pollen grains from conifer trees found in the same layer as the aquatic plant seeds.
Again, independent experts challenged the findings, arguing that conifer seeds are unreliable indicators.
The latest study now provides support for the two previous efforts by applying carbon-14 dating to other organic materials that were trapped in the mud.
“Three independent sources of carbon pollen grains, seeds, and organic sediments have now been dated by different laboratories,” and they all point to roughly the same age, Jason Windingstad of the University of Arizona, a member of the team behind the new study, told Reuters.
The new findings suggest that Homo sapiens, which emerged in Africa about 300,000 years ago, reached the Americas thousands of years earlier than previously believed.
They do not, however, offer new information about the route they followed.
The prevailing view is that the first settlers arrived via a land bridge that appeared between Asia and Alaska when sea levels dropped in the Pacific during the Ice Age.
An alternative theory proposes that they reached the west coast of the United States from Asia by sea.
