23,000-Year-Old Footprints Suggest That Humans Were Already in North America During the Ice Age

Ancient footprints discovered in White Sands National Park, New Mexico, confirm that humans arrived in North America well over 20,000 years ago, some 7,000 years earlier than previously thought.

A recent study published in the journal Science has confirmed the astonishing age of human footprints found in White Sands National Park in New Mexico. The footprints, which were first discovered in 2018, date back to about 22,000 to 23,000 years ago, making them the oldest evidence of human presence in the Americas.

The footprints were preserved in the dried-up bed of Lake Otero, a large lake that existed during the last ice age. The lake was a rich source of food and water for animals and humans alike, and its shores were dotted with tracks of mammoths, ground sloths, camels, dire wolves, American lions, and other extinct megafauna. Among these tracks, researchers identified hundreds of human footprints, some of which showed signs of running, jumping, and carrying heavy loads.

In their initial study published back in 2021, the research team used radiocarbon dating on seeds from the aquatic plant Ruppia cirrhosa found within the layers of earth around the footprints. However, because R. cirrhosa grew in the lake, it absorbed carbon-14 from the water, potentially skewing the radiocarbon dating results by making the seeds and footprints seem older than their actual age, as the water might have contained carbon from much older nearby sediments.

So, the White Sands team revisited the site to collect new samples, focusing on pollen extracted from sediment layers associated with various sets of footprints. They isolated and radiocarbon dated pollen from pine trees, which are terrestrial and therefore have no risk of having absorbed older carbon from the water. Additionally, they gathered quartz grains from a clay layer above the oldest tracks.

The researchers used a technique called optically stimulated luminescence (OSL) to determine the age of the quartz grains from the sediment layers by looking at how long they were exposed to sunlight. According to the team’s findings, the pollen dates back to a range of 23,000 to 21,000 years, while the OSL analysis indicates that the quartz grains were buried between 21,400 and 18,000 years ago.

The results were surprising: the footprints were much older than previously thought, predating the widely accepted date of human arrival in the Americas by at least 7,000 years. This challenges the conventional view that humans first entered the continent via a land bridge connecting Siberia and Alaska around 16,000 years ago.

“It’s a paradigm-shattering result,” said Kathleen Springer, a USGS geologist. “People were in New Mexico during the Last Glacial Maximum, when the massive ice sheets farther north were [impassable]—that just flies in the face of all ideas about migrations and migratory routes,” she added, referring to the peak of the last ice, which occurred between 26,000 and 20,000 years ago.

The footprints also shed light on the lifestyle and behavior of these ancient humans, who lived in a harsh and unpredictable environment. A total of 61 footprints were unearthed, predominantly from teenagers and children. The prevailing theory suggests that adults engaged in skilled tasks near the lake, with teenagers handling activities such as fetching and carrying, evident in their more abundant footprints. The smaller footprints of young children might be attributed to playful activities, resulting in a higher number of prints.

Other footprints show humans coexisting and interacting with extinct ice age animals. In one set, human footprints suggest individuals stalking a giant sloth, as evidenced by human footprints found within the sloth’s tracks, indicating tracking. Regrettably for the hunters, there is no evidence indicating a successful outcome from this particular hunt.

In 2018, researchers uncovered footprints believed to be of a female, revealing a narrative that might seem familiar. The prints depict her walking nearly a mile, occasionally accompanied by toddler footprints. Evidence suggests she carried the child, alternating sides and occasionally setting the child down, causing the footprints to widen and slip in the mud due to the added weight.

The researchers hope to continue their work at White Sands National Park, where they believe there are more footprints waiting to be uncovered. They also hope that their findings will inspire more research on other sites in the Americas that may hold clues to the early history of human migration and settlement.

Sources: 1, 2, 3, 4, 5