Ancient Human Footprints in New Mexico: New Dating Techniques Suggest an Even Older Origin

Human footprints discovered in New Mexico's White Sands National Park made headlines two years ago due to their unexpectedly ancient age, dating back to approximately 22,000 years ago. Now, fresh evidence from two distinct dating methods supports these findings, potentially resolving the earlier controversy. This report was published in the October 6th issue of Science.

This revelation contributes to the growing body of proof suggesting that humans arrived in North America far earlier than previously believed.

Archaeologist Loren Davis from Oregon State University underscores the significance of accurately determining the age of these footprints. Understanding the timeline of human presence in the Americas is crucial for archaeological research.

In 2021, researchers described more than 60 footprints preserved in what was once mud near an ancient lake in present-day New Mexico. Radiocarbon dating of seeds from aquatic plants found in and around these footprints, spanning multiple layers of rock, suggested human presence in the area for approximately two millennia, between roughly 23,000 and 21,000 years ago. This finding contradicted the long-held theory that the first humans in North America arrived from Siberia via a land bridge approximately 16,000 to 14,000 years ago.

However, some scientists raised concerns that the aquatic plants used for dating might have absorbed ancient carbon from groundwater, a well-known phenomenon that could lead to inaccurate age estimates. Davis, who co-authored a critique of the 2021 paper, noted the potential for exaggerated age perspectives from these plants.

Geologist Jeff Pigati from the U.S. Geological Survey's Geosciences and Environmental Change Science Center in Denver anticipated such criticism from the outset. Therefore, independent evaluation of the ages using various dating techniques became essential.

To supplement their prior research, Pigati and his team radiocarbon-dated pollen found in the same layers as some of the footprints. The pollen primarily originated from land plants, including pine, spruce, and fir trees, thus circumventing concerns related to groundwater carbon. Additionally, the researchers gathered quartz grains situated above the lowest footprints and employed a dating method to estimate the duration of quartz burial.

The pollen dating yielded an age range of approximately 23,400 to 22,600 years old, while the quartz dating indicated a minimum age of about 21,500 years old. Both results align closely with the earlier age estimate.

This convergence of dating methods from different angles enhances the robustness of the findings and makes them challenging to dispute, according to Pigati.

However, Davis suggests further exploration of quartz ages from additional rock layers with footprints to achieve a more comprehensive resolution of the issue.

The authors acknowledge that many of the other layers are too thin for sampling, and collecting a sediment sample from such layers would entail mixing multiple layers of different silts, sands, and clays, complicating the results.

Despite potential uncertainties in individual dating methods, Bente Philippsen, a physicist at the Norwegian University of Science and Technology in Trondheim, emphasized in a commentary within the same issue of Science that "the data overall from the [new] study strongly indicate human presence in the Americas" around 22,000 years ago.

One certainty remains: there is still much to learn about these ancient footprints, as coauthor Kathleen Springer, a geologist at the USGS's Geosciences and Environmental Change Science Center, noted. She stated that this paper represents the latest chapter in the ongoing story of the White Sands discovery.

Scientists and archaeologists continue to investigate the site, hoping to uncover more clues about the lives and movements of the individuals who left their marks in the sands of time.

As our understanding of these footprints deepens, they remain a testament to the enduring curiosity of humanity and our unceasing quest to unravel the mysteries of our past.

[Source: Study Link - sciencesnew.org]