New research has uncovered compelling evidence that prehistoric human footprints in New Mexico may rewrite the history of human presence in the Americas—an intriguing and previously controversial topic.

This question gained widespread attention in 2021 when scientists claimed to have discovered the oldest human footprints ever found in North America, dating back approximately 23,000 years. This discovery ignited debates and raised questions about the methodologies used. Until then, the widely accepted theory was that humans colonized North America about 15,000 years ago, following the last ice age.

Now, the original researchers have responded with additional evidence and explanations in a recent study published in the journal Science.

The Original Discovery

In a study published in September 2021 in Science, it was reported that the oldest known human footprints in North America had been unearthed at White Sands National Park in New Mexico. Researchers identified around 60 fossilized footprints buried in layers of gypsum soil on a vast playa in the Tularosa Basin. By employing carbon dating techniques on seeds found within the footprints, the U.S. Geological Survey estimated that these prints could be up to 23,000 years old.

According to the 2021 study, it was suggested that humans might have migrated from Asia into the Americas between 26,000 to 19,000 years ago, likely via land connecting what is now Russia and Alaska during the last ice age.

This discovery challenged established archaeological theories regarding the peopling of the American continent and its timeline. The reported age of the footprints contradicted the traditional belief that humans did not reach the Americas until a few thousand years before rising sea levels submerged the Bering land bridge between Russia and Alaska, which occurred approximately 15,000 years ago.

The controversy surrounding the footprints mainly revolved around the method used to determine the age of the seeds. In 2022, a separate group of scientists published a study suggesting that the seeds were significantly younger than 23,000 years, casting doubt on the previous findings.

The Latest Developments

In the study released on Thursday, the scientists behind the 2021 study defended their methodology and findings, reinforcing their claim that humans were indeed present in North America 23,000 years ago.

The new study conducted multiple independent age estimates of the White Sands footprints, all of which supported the conclusions of the previous study. Jeff Pigati, a research geologist with the U.S. Geological Survey, explained, «We always knew that we would have to independently evaluate the accuracy of our ages to convince the archaeological community that the peopling of the Americas occurred far earlier than traditionally thought.»

According to the new study, with three separate lines of evidence—samples of pollen grains and two different sediments—all pointing to the same approximate age, there is strong support for the footprints’ age falling within the 21,000 to 23,000-year range.

Kathleen Springer, a USGS research geologist and co-lead author of the new study, emphasized the rigorous testing they conducted. She stated that they were confident in the original seed ages but aimed to gain community confidence in their findings. She added, «Our new ages, combined with the strong geologic, hydrologic, and stratigraphic evidence, unequivocally support the conclusion that humans were present in North America during the last Glacial Maximum.»

Thomas Stafford, an independent archaeological geologist in Albuquerque, New Mexico, who was not involved in the study, expressed his initial skepticism and subsequent conviction. He noted that when three entirely different methods converge to indicate a single age range, it carries significant weight.

Is the Debate Settled?

While the recent research has provided substantial evidence in favor of the earlier findings, some questions remain. According to Loren Davis of Oregon State University, whose team questioned the original findings in 2022, the dating issue remains unresolved until more information becomes available regarding when the footprints were buried.