The footprints look ordinary enough, those of young kids and teenagers walking near what was once a lake. But a new study in Science adds a remarkable twist—scientists say the prints were made about 23,000 years ago in what is now White Sands National Park in New Mexico. The assertion challenges a long-held belief that the first humans came to North America only about 13,000 years ago, when glaciers retreated and made their path possible, reports the New York Times. Previous research has raised doubts about the latter timeline, but proof has been elusive. Which is why National Geographic describes this new study as a "bombshell" and quotes an archaeologist with Mexico's Autonomous University—uninvolved in the study—who says "a discovery like this is very close to finding the Holy Grail."
- A study author: "It is, in my view, the first unequivocal evidence of human presence in the Americas" amid the last Ice Age, says Daniel Odess, chief of science and research at the National Park Service and a senior author of the report, per the Wall Street Journal. "The footprints are inarguably human."
- Potential weak spot: Scientists determined the age of the prints by dating seeds found embedded in the prints. Critics in various stories note that it's possible the seeds absorbed "old" carbon from their surroundings—from carbonate rock, for example—which could distort their age. "I’d like to see stronger data," one skeptic tells the Journal. Another, however, tells National Geographic that even if the seeds were distorted in such a way, the difference probably wouldn't be more than a few thousand years.
- Erosion's curse: The Times notes that the lake where the prints were made dried up thousands of years ago. Sediment then filled in the prints, but modern erosion has exposed them—a mixed blessing. The same erosion could destroy them in a matter of years, or even months. Meaning undiscovered prints will likely emerge and disappear without anyone knowing. "It's heartbreaking," says David Bustos, the park official who first found these prints.
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