Unlocking the Mysteries of Ancient Footprints in White Sands: A Journey Through Time and Controversy
A group of human footprints can be found beneath the White Sands National Park in New Mexico’s supposedly desolate desert. These imprints are far more than just chance scribbles; they are old photographs that were preserved in gypsum-rich sand. These tracks tell tales of hunters pursuing enormous sloths, people trudging through mud while pulling a toddler behind them, and kids jumping gleefully in puddles.
Researchers studying these prints have, however, been stumped by the question of when they were first created. Unexpectedly, the answer was given in a 2021 study paper: “These footprints may be as old as 21,000 to 23,000 years old, making them some of the earliest signs of human presence in the Americas.
The outcome sparked interest and skepticism, with requests for more research to support the astounding claims. The age of the tracks was further determined in a new study that was published on Thursday in the journal Science, adding to the mounting evidence supporting those startlingly early dates.
“This opens up a whole new chapter in our understanding of the peopling of the Americas,” says Summer Praetorius, a paleoceanographer at the U.S. Geological Survey who was not involved in the work.
The argument, according to some researchers, is still open. Since about a century ago, there has been debate over the time that humans first arrived in the Americas. The oldest stone tools that have been linked to the Clovis culture—named for the town in New Mexico close to where they were discovered—are believed to have been created no earlier than 13,000 years ago. Most scientists recently agreed that humans descended from earlier hominins by a few thousand years.
However, an increasing number of locations offer intriguing evidence of far earlier human existence. At the height of the Last Glacial Maximum, according to dates for human footprints found at White Sands, people lived deep within the North American continent. At the time, it was believed that ice sheets up to two miles thick would prevent travel from Siberia across the Bering Land Bridge.
Geologist Kathleen Springer from the U.S. Geological Survey acknowledged, “We anticipated controversy from the start.” Consequently, when the team released their initial report, they had already planned further research.
In the 2021 study, seed analysis from the aquatic plant ruppia was used to establish dates, but concerns were raised about the reservoir effect potentially affecting radiocarbon results for these plants. For the recent study, the team opted for a different approach, analyzing the carbon isotopes of ancient pollen from terrestrial plants. They collected more than 75,000 pollen grains from layers interspersed within the trackways at the New Mexico site, conducting a thorough analysis.
After nearly a year of meticulous work, the investigation revealed pollen indicative of a lush environment during the Last Glacial Maximum, characterized by cooler temperatures. The landscape featured abundant fir, spruce, pine, and sagebrush. The largest pollen grains, predominantly pine, underwent carbon analysis at Lawrence Livermore National Laboratory. Additionally, the team employed optically stimulated luminescence to date a layer of sediments at White Sands, illuminating how long quartz sand had remained below the surface.
Jeff Pigati, a geologist at the geological survey and a study co-author, emphasized the convergence of seed ages, pollen ages, and luminescence ages, making it challenging to dispute the findings. This sentiment is shared by many independent scientists.
Edward Jolie, an archaeologist at the University of Arizona, commended the study’s scientific response to criticism and highlighted the significance of these discoveries for Native communities, affirming their long-held beliefs.
Nevertheless, some scientists maintain reservations. Loren Davis, an archaeologist at Oregon State University, acknowledged that no method is flawless. He stressed the need for more luminescence dates from sediment layers throughout the track sites to enhance confirmation.
Thomas Stafford, a geochronologist with Stafford Research not involved in the research, noted that the distinct conditions affecting each method’s accuracy actually strengthen the latest findings. He underscored the significance of three different dating methods producing similar ages, bolstering the case for the 21,000-year-old dates.
While debate persists regarding these footprints, White Sands promises numerous additional discoveries, with thousands of tracks dotting the saline landscape. Dr. Jolie anticipates ongoing research in this remarkable area for years to come.