Earliest Americans: 23,000 Year Old Footprints

For decades, archaeology students were taught that humans arrived in North America roughly 13,000 years ago. A groundbreaking discovery at White Sands National Park in New Mexico has shattered that timeline. Fossilized footprints confirm that humans walked across the continent at least 21,000 to 23,000 years ago, pushing back the clock on American history by nearly 10,000 years.

The Discovery at Ancient Lake Otero

The evidence comes from the dry basin of an ancient body of water known as Lake Otero. During the Ice Age, this area was not the dry desert of shifting gypsum dunes we see today. It was a muddy, grassy wetland teeming with life. As the water levels of the lake fluctuated, humans and animals walked across the soft mud. When the ground dried, these tracks hardened and were eventually buried by new layers of sediment, preserving them for millennia.

The site contains thousands of footprints. Analysis by researchers from the US Geological Survey (USGS) and international universities identified tracks from various individuals. Interestingly, most of the prints belong to children and teenagers. This suggests that while adults might have been hunting or foraging further away, young people were tasked with fetching water or working near the safety of the lake edge.

These human tracks are not alone. They appear alongside the footprints of Ice Age megafauna, including:

• Columbian mammoths
• Giant ground sloths
• Dire wolves
• Camels

In some incredible instances, the footprints tell a story of interaction. There are sequences where human prints appear inside the tracks of a giant sloth, indicating that a human stepped into the animal’s footprint shortly after it passed.

Solving the Dating Controversy

When the findings were first published in the journal Science in September 2021, they caused a major stir in the scientific community. The dates were so old that many experts were skeptical.

The initial radiocarbon dating relied on seeds from an aquatic plant called ditch grass (Ruppia cirrhosa). Critics pointed out a potential flaw known as the “hard water effect.” Aquatic plants often absorb carbon dissolved in the groundwater rather than from the atmosphere. If the groundwater flows through old limestone, it can contain carbon that is thousands of years old. This could theoretically make the seeds, and the footprints, appear much older than they actually were.

To settle the debate, the research team returned to the site for a new study, the results of which were released in October 2023. Led by USGS research geologists Kathleen Springer and Jeff Pigati, the team used two independent dating methods to verify their original claim.

Method 1: Conifer Pollen

The team isolated approximately 75,000 grains of pollen from the exact same sediment layers that held the footprints. Unlike the aquatic ditch grass, this pollen came from terrestrial plants like fir, spruce, and pine trees. These trees extract carbon directly from the atmosphere, meaning they are not subject to the hard water effect. The radiocarbon dating of the pollen matched the original seed dates perfectly, placing the footprints between 21,000 and 23,000 years ago.

Method 2: Optically Stimulated Luminescence (OSL)

The team also used a technique called Optically Stimulated Luminescence. This method dates the last time quartz grains in the soil were exposed to sunlight. Once the quartz is buried, it accumulates energy from background radiation in the soil. By measuring this energy, scientists can determine exactly when the mud was buried. The OSL results confirmed the sediment layers were indeed laid down during the Last Glacial Maximum, aligning with the pollen and seed dates.

Implications for Human Migration

The confirmed age of these footprints forces a complete rewrite of migration theories.

For years, the “Clovis First” hypothesis dominated archaeology. It suggested that the Clovis people, known for their distinct fluted stone points, were the first inhabitants roughly 13,000 years ago. They were thought to have crossed the Bering Land Bridge from Siberia when the ice sheets retreated enough to open an ice-free corridor.

The White Sands footprints prove people were in New Mexico during the Last Glacial Maximum (LGM). The LGM was the peak of the Ice Age, roughly 19,000 to 26,000 years ago. During this period, two massive ice sheets (the Laurentide and the Cordilleran) covered much of Canada and the northern United States. These ice sheets had merged, creating an impassable wall of ice from the Atlantic to the Pacific.

If humans were already in New Mexico 23,000 years ago, they must have arrived before those ice sheets closed off the inland route. Alternatively, they may have traveled down the Pacific coast by boat, skirting the edge of the ice.

A Glimpse into Ice Age Life

Beyond the dates, the White Sands fossils offer a rare, intimate look at daily life in the Pleistocene era. Traditional archaeology often relies on stone tools or bones, which are static objects. Footprints capture movement and behavior.

The tracks show:

• Play and Work: The prevalence of teen and child prints suggests a community structure where young people contributed to daily labor.
• Speed: Biomechanics experts analyzed the stride length of some tracks and determined people were moving at a fast walk or jog, roughly 3.8 miles per hour.
• Carrying Loads: Some tracks show weight distribution consistent with a person carrying a heavy object, or perhaps a child, on one hip. As the tracks progress, the weight shifts or the tracks change, suggesting the person put the child down.

The preservation of these prints is fragile. As erosion removes the sediment covering them, they are exposed to the elements and can disappear in a matter of months or years. The work done by the National Park Service and the USGS is a race against time to document this physical evidence of the earliest known Americans before the wind erodes it away.

Frequently Asked Questions

Where exactly were these footprints found? They were found in White Sands National Park in southern New Mexico. They are located on the alkali flats of what was once Lake Otero.

How do we know the footprints aren’t just 13,000 years old? The 2023 study used pollen dating and Optically Stimulated Luminescence (OSL) to confirm the age. Both methods independently pointed to a date range of 21,000 to 23,000 years ago, ruling out the younger Clovis timeline.

Did these people hunt mammoths? While mammoth tracks are found in the same area, there is no direct evidence at White Sands (like a spear point in a bone) proving a kill took place there. However, the footprints show humans and megafauna shared the terrain, and humans were certainly tracking these animals.

Why haven’t we found their bones? Fossilization of bones is rare and requires very specific chemical conditions. Footprints in drying mud, however, can be preserved more easily under the right rapid-burial conditions. It is common to find millions of footprints for every single skeleton discovered.

Are the footprints open to the public? Most of the fossilized footprints are in remote areas of the park and are fragile. However, the park service sometimes offers guided tours, and there are exhibits at the visitor center explaining the findings.