'Incredible:' Oldest known human footprints in North America discovered at national park

LAS CRUCES — The oldest known human footprints in North America have been discovered at White Sands National Park in New Mexico. 

Researchers identified approximately 60 fossilized footprints buried in layers of gypsum soil on a large playa in the Tularosa Basin in findings published in the journal Science on Thursday.

By carbon dating seeds embedded in the footprints, the U.S. Geological Survey estimated the prints were up to 23,000 years old. 

The article reports researchers believe humans could have crossed from Asia into the Americas 26,000 to 19,000 years ago, through land connecting what is now Russia and Alaska, during the last ice age. From there, they are thought to have settled a now mostly submerged region called Beringia, but found their way south blocked by glaciers.

The discovery could upset existing theories of how human beings came to populate the American continent, and how long ago.

Research over recent decades suggested people reached today's continental North America by boat at least 16,000 years ago. Before that, archaeologists thought the first human arrivals walked through a corridor between glaciers by around 13,500 years ago.

If the dating of the new discovery in New Mexico is correct, it establishes the strongest evidence yet that human beings reached the Americas thousands of years earlier than previously supposed by archaeologists, the paper states, before advancing glaciers closed migration routes from Asia.

"This study illustrates the process of science — new evidence can shift long-held paradigms," U.S. Geological Survey Acting Rocky Mountain Regional Director Allison Shipp said. 

Research teams included scientists from White Sands National Park, the National Park Service, the U.S. Geological Survey, Bournemouth University, University of Arizona and Cornell University in consultation with the park’s Native American partners.

Two historic Apache trails cross what is now the park. The descendants of the original Apache who settled in the area are the Mescalero Apache.

“These incredible discoveries illustrate that White Sands National Park is not only a world-class destination for recreation, but is also a wonderful scientific laboratory that has yielded groundbreaking, fundamental research,” White Sands Superintendent Marie Sauter said in a news release.

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Dynamic landscape makes dating difficult

David Rachal, a geomorphologist based in Las Cruces who was not involved in this project, published a research paper in April warning that the geology of White Sands and the bed of Paleolake Otero are dynamic.

Layers of sediment bearing trackways of humans and large ice age animals, or megafauna, have eroded, moved around and exposed layers over time. The lake itself has risen and fallen and the shoreline has shifted.

On Thursday, Rachal said the dynamics make accurate dating of specific tracks very difficult, as when footprints occurring many thousands of years apart might be superimposed.

Rachal praised the team's work before adding one note of caution about how these findings characterize other trackways at the site.

“You can’t dispute the dates, the prints are amazing, everything lines up, it’s perfect,” he said, noting that the team was working in an area with superior conditions for trackway preservation.  

“The only thing I’m concerned about is that it’s not that clean of a landscape,” he added, warning that the landscape at White Sands “has experienced a tremendous amount of geologic change over a short timeframe and you need to interpret these tracks that are exposed in a surface context, as a dynamic landscape.”

Note: Story updated at 4:45 p.m. Sept. 23 with comments from geomorphologist.

Algernon D'Ammassa can be reached at 575-541-5451, adammassa@lcsun-news.com or @AlgernonWrites on Twitter.