Debate settled? Oldest human footprints in North America really are 23,000 years old, study finds

Fossilized human footprints in beige and white sand at White Sands in New, Mexico.
Human footprints at White Sands in New, Mexico date to between 21,000 and 23,000 years ago. (Image credit: National Park Service)

Paleo-human footprints dotting White Sands National Park in New Mexico are 23,000 to 21,000 years old, making them the oldest known fossilized trackways left by people in North America, a new study finds. However, not everyone agrees with the results.

The study, which used two dating techniques to verify the trackway's age, is a response to criticism that an earlier study published in 2021 by the same group used unreliable material to date the footprints. Now, all three results — the earlier, controversial one and the two new findings from different dating techniques — point to the trackways being 23,000 to 21,000 years old. That means they date to around the time of the Last Glacial Maximum (26,500 to 19,000 years ago), the coldest part of the last ice age.

The trackway's early age is a big deal. Previously, archaeologists thought that the Clovis people — known for their sharp-edged, leaf-shaped stone points found at archaeological sites across North America — were the first humans to come into the Americas around 13,000 years ago. Only in the past few decades have archaeologists discovered solid evidence for the pre-Clovis, or people who were in the Americas before 13,000 years ago, but many of those newly uncovered sites had shaky evidence or were only a few thousand years older than the Clovis.

The White Sands trackway is now the oldest site in North America with direct evidence of humans and it significantly pushes back the arrival date of the first Americans.

Related: The 1st Americans were not who we thought they were

An illustration that depicts different points in time at the White Sands site during the Last Glacial Maximum, when human and megafaunal lived side by side. (Image credit: Karen Carr/National Park Service)

"When the first paper came out, a lot of archaeologists reached out and told us, 'It was just a matter of time. We knew that people were here earlier,'" said Jeffrey Pigati, who co-lead the study with Kathleen Springer. Both are U.S. Geological Survey research geologists at the Geosciences and Environmental Change Science Center in Denver. "Now we have rock-solid evidence of people here during the Last Glacial Maximum," he said.

But in 2022, a group of archaeologists pointed out in a rebuttal that the radiocarbon dated material used in the first paper — the seeds of the aquatic plant Ruppia cirrhosa — were unreliable.

Scientists had found the seeds smooshed into the footprints, providing organic remnants that could be dated by examining the radioactive decay of their carbon-14. But "Ruppia is a notorious misreporter of its age," Loren Davis, a professor of anthropology at Oregon State University who co-authored the rebuttal, told Live Science. Unlike other once-living organisms that inhale carbon-14 from the atmosphere, "Ruppia prefers to get its carbon from lake water, it doesn't get it from the atmosphere. And in doing so, if there is old carbon being put into the groundwater, then you'll get old ages on plants that are not that old," Davis said.

In the rebuttal, Davis and his colleagues suggested the White Sands group use optically stimulated luminescence (OSL) dating, a technique that estimates how much time has passed since quartz or feldspar grains were last exposed to intense heat or sunlight.

So, for the new paper, published Thursday (Oct. 5) in the journal Science, the researchers did just that.

The team examined quartz grains under the footprints with OSL dating. They found that the layers with the footprints had a minimum age of about 21,500 years old.

The team also isolated and then radiocarbon dated three samples of earth that each contained 75,000 conifer pollen grains from the same footprint layers as the Ruppia seeds. Confer plants get their carbon-14 from the atmosphere, meaning they don't have the same pitfalls as Ruppia. The ages of around 23,000 years ago matched those of both the seeds and the quartz grains. "If the seed ages and the pollen ages and the luminescence ages all agree, then it's case closed," Pigati said. "We can stop arguing about the ages."

Actually, not yet, Davis said.

According to a map showing where the White Sands team took the OSL samples, "it is clear that the three OSL ages come from sediments that are stratigraphically beneath the trackway horizons," Davis told Live Science in an email. So it's possible that the quartz grains were deposited first and that the footprints were deposited on top of them at a later date, possibly between 19,800 and 16,200 years ago, as one OSL sample demonstrates, he said.

"This is why it is critical that the authors continue their efforts to get OSL ages from the sediments that actually buried the footprints," Davis said. He added that it's possible that erosion of older sediments at the lake basin could have caused fossil pollen to be redeposited elsewhere at a later time, meaning that the pollen could be older than the footprints.

Springer and Pigati said the OSL samples were taken from the same layer as the footprints, while Davis stood by his interpretation of their data.

But others were impressed by the findings.

A single human footprint at White Sands National Park. (Image credit: National Park Service)

"I think it's a really great contribution and a very convincing and detailed case," Thomas Higham, an archaeological scientist and radiocarbon dating specialist at the University of Vienna who was not involved with the study. He disagreed with Davis' take that more OSL data is needed. "Getting those samples is not an easy feat," Higham said, adding that the team took the lower-dated layer into account and used a model to bracket the ages of the footprints above them.

The initial 2021 finding was "a groundbreaking result," Higham told Live Science. "I think that duplicating and reproducing those results is a hallmark of the scientific method."

Editor's note: Updated at 12:05 p.m. EDT on Oct. 12 to include that Springer and Pigati disagree with Davis' assertion that the OSL samples were taken from beneath the trackway, and that Davis stands by his interpretation of the data.

Laura Geggel
Editor

Laura is the archaeology and Life's Little Mysteries editor at Live Science. She also reports on general science, including paleontology. Her work has appeared in The New York Times, Scholastic, Popular Science and Spectrum, a site on autism research. She has won multiple awards from the Society of Professional Journalists and the Washington Newspaper Publishers Association for her reporting at a weekly newspaper near Seattle. Laura holds a bachelor's degree in English literature and psychology from Washington University in St. Louis and a master's degree in science writing from NYU.

  • SouthSideRich
    Which indicates that we don't really know how far back humanity actually goes. What is also intriguing is the lack of fossilized records showing a transition between any species. The official narrative insists that evolution created everything. However, there's no record of that. There is a record of every single recent civilization saying that we were genetically altered and provided technology by other Beings. Might 'those who came from above' to create our latest upgrades still be in charge and directing our lives via secret societies, manipulation, and control over most everything?
    Wouldn't it be interesting if it was really us who created all of this and intentionally forgotten that we did so; just so that we can enjoy the marvel of our abilities to continue creating, without knowing too much -in order to- keep us intrigued?
    So far, so good... What an adventure!
    Reply
  • Otto_Didactic
    The site is fake. The tracks are unnatural. Next time you are at the beach look and see if anybody has toe prints like that. https://its-all-fake.com/2023/10/08/fake-footprints-at-white-sands-national-park-and-the-world-heritage-tribute-to-the-new-world-order/
    Reply
  • backcountry164
    SouthSideRich said:
    Which indicates that we don't really know how far back humanity actually goes. What is also intriguing is the lack of fossilized records showing a transition between any species. The official narrative insists that evolution created everything. However, there's no record of that. There is a record of every single recent civilization saying that we were genetically altered and provided technology by other Beings. Might 'those who came from above' to create our latest upgrades still be in charge and directing our lives via secret societies, manipulation, and control over most everything?
    Wouldn't it be interesting if it was really us who created all of this and intentionally forgotten that we did so; just so that we can enjoy the marvel of our abilities to continue creating, without knowing too much -in order to- keep us intrigued?
    So far, so good... What an adventure!
    In no way does it indicate any such thing. In fact, your entire post is bad fiction.
    Reply
  • backcountry164
    Much of the pushback comes from the fact that these pre-clovis people likely came from Europe rather than Aisa. Science is supposed to be open-minded but, sadly, scientists rarely are...
    Reply
  • backcountry164
    Otto_Didactic said:
    The site is fake. The tracks are unnatural. Next time you are at the beach look and see if anybody has toe prints like that. https://its-all-fake.com/2023/01/01/indians-are-fake-thread/
    Thanks for the link. It was literally the dumbest thing that I've ever read on the internet. And that's sayin' something...
    Reply
  • SouthSideRich
    backcountry164 said:
    In no way does it indicate any such thing. In fact, your entire post is bad fiction.
    Fiction it may be. Bad to you it may be.
    However we don't really know where any of this came from, what we've got here, nor where it's going. To believe otherwise is ignorance and some people prefer to embrace that.
    Reply
  • mama turtle
    Otto_Didactic said:
    The site is fake. The tracks are unnatural. Next time you are at the beach look and see if anybody has toe prints like that. https://its-all-fake.com/2023/10/08/fake-footprints-at-white-sands-national-park-and-the-world-heritage-tribute-to-the-new-world-order/
    The tracks weren't made last week or even last year. They were made 23,000 years ago. It's not unreasonable to think that footprints would change in 23,000 years, especially since the development of hard shoes. When you put hard shoes on the feet of growing children their feet conform to the shape of the shoes. That alone is enough to explain the difference between footprints then and footprints now.
    Reply
  • Hartmann352
    U.S. Geological SurveySummary:

    New research reaffirms that human footprints found in White Sands National Park, NM, date to the Last Glacial Maximum, placing humans in North America thousands of years earlier than once thought. In September 2021, scientists announced that ancient human footprints discovered in White Sands National Park were between 21,000 and 23,000 years old. This discovery pushed the known date of human presence in North America back by thousands of years and implied that early inhabitants and megafauna co-existed for several millennia before the terminal Pleistocene extinction event. In a follow-up study, researchers used two new independent approaches to date the footprints, both of which resulted in the same age range as the original estimate.

    "The immediate reaction in some circles of the archeological community was that the accuracy of our dating was insufficient to make the extraordinary claim that humans were present in North America during the Last Glacial Maximum. But our targeted methodology in this current research really paid off," said Jeff Pigati, USGS research geologist and co-lead author of a newly published study that confirms the age of the White Sands footprints.

    The controversy centered on the accuracy of the original ages, which were obtained by radiocarbon dating. The age of the White Sands footprints was initially determined by dating seeds of the common aquatic plant Ruppia cirrhosa that were found in the fossilized impressions. But aquatic plants can acquire carbon from dissolved carbon atoms in the water rather than ambient air, which can potentially cause the measured ages to be too old.

    "Even as the original work was being published, we were forging ahead to test our results with multiple lines of evidence," said Kathleen Springer, USGS research geologist and co-lead author on the current Science paper. "We were confident in our original ages, as well as the strong geologic, hydrologic, and stratigraphic evidence, but we knew that independent chronologic control was critical."

    For their follow-up study, the researchers focused on radiocarbon dating of conifer pollen, because it comes from terrestrial plants and therefore avoids potential issues that arise when dating aquatic plants like Ruppia. The researchers used painstaking procedures to isolate approximately 75,000 pollen grains for each sample they dated. Importantly, the pollen samples were collected from the exact same layers as the original seeds, so a direct comparison could be made. In each case, the pollen age was statistically identical to the corresponding seed age.

    "Pollen samples also helped us understand the broader environmental context at the time the footprints were made," said David Wahl, USGS research geographer and a co-author on the current Science article. "The pollen in the samples came from plants typically found in cold and wet glacial conditions, in stark contrast with pollen from the modern playa which reflects the desert vegetation found there today."

    In addition to the pollen samples, the team used a different type of dating called optically stimulated luminescence, which dates the last time quartz grains were exposed to sunlight. Using this method, they found that quartz samples collected within the footprint-bearing layers had a minimum age of ~21,500 years, providing further support to the radiocarbon results.

    With three separate lines of evidence pointing to the same approximate age, it is highly unlikely that they are all incorrect or biased and, taken together, provide strong support for the 21,000 to 23,000-year age range for the footprints.

    The research team included scientists from the USGS, Lawrence Livermore National Laboratory, the National Park Service, and academic institutions. Their continued studies at White Sands focus on the environmental conditions that allowed people to thrive in southern New Mexico during the Last Glacial Maximum and are supported by the Climate Research and Development Program | U.S. Geological Survey and USGS-NPS Natural Resources Protection Program

    See: https://www.sciencedaily.com/releases/2023/10/231005161809.htm
    New research reaffirms that human footprints found in White Sands National Park, New Mexico, date to the Last Glacial Maximum, placing humans in North America thousands of years earlier than once thought.
    Hartmann352
    Reply
  • backcountry164
    SouthSideRich said:
    Fiction it may be. Bad to you it may be.
    However we don't really know where any of this came from, what we've got here, nor where it's going. To believe otherwise is ignorance and some people prefer to embrace that.
    ?? Lol!! After posting that link you clearly have no business suggesting other people are ignorant!!
    Reply