Thousands of ancient footprints left by Ice Age humans and animals stretch for miles across the blinding white surfaces of New Mexico’s White Sands National Park. The phenomenal collection of prints provides a snapshot of life, capturing moments when humans crossed paths with now-extinct Ice Age beasts, including enormous ground sloths and mammoths. This month, NOVA’s Ice Age Footprints explores the stories these footprints tell, including remarkable new evidence of people who lived on the North American continent earlier than archaeologists had previously known. The film premieres on May 25 on GBH 2.

“The story of human habitation and migration around the world keeps getting more complicated,” said Chris Schmidt, NOVA co-executive producer. “The findings in New Mexico significantly push back the scientifically verified date of human habitation, and they raise a lot of questions regarding who these people were and how they got to North America.”

It’s important to note that the footprints were not just “discovered,” said Julia Cort, NOVA co-executive producer. “Local Indigenous people have long known about them, but this is the first time scientists have been able to use radiocarbon dating technology to try to pinpoint when they were made.”

The prints suggest that humans were in North America as long as 23,000 years ago—at the height of the last Ice Age—eclipsing previous estimates of 16,000 years.

Hosted by Kirk Johnson, Sant Director of the Smithsonian’s National Museum of Natural History and host of NOVA’s 2020 documentary Polar Extremes, the film also features archaeologist Joe Watkins, a member of the Choctaw Nation of Oklahoma, and Kim Charlie from the Pueblo of Acoma in New Mexico.

“We all talk about having been here forever. We’ve never been anywhere else,” said Watkins in the film. “Now we have the evidence. It really does put our footprints firmly into the past here in North America. These are our relatives. We’ve been here since time immemorial.”

Bringing that history to light is an important part of the film, said Cort. “There’s a long history of some White historians minimizing or delegitimizing Indigenous people’s histories and legacy of living on these lands,” she said. “Only recently have there been real efforts to make sure Indigenous peoples have agency over their own histories.”

Digging beneath the surface of the sand, archaeologists not only discovered multiple layers of footprints, they also uncovered long-buried seeds that gave them the raw material they needed to use carbon dating to estimate the age of the prints. “It’s amazing that the archaeologists were lucky enough to find that plant matter that allowed them, in a very credible way, to associate a date with the footprints,” said Schmidt.

Footprints, as opposed to the more typical archaeological find of pottery or stones, are especially remarkable, says Cort. “These are remnants of actual people moving through the world. And the footprints tell stories—we can see that a person carried a child over a long distance, then put the child down and lifted them up again, because the child’s footprints appear for a little bit on the ground and then disappear again,” she said. “To be able to reconstruct human activity in this way is so profound. You can almost feel the presence of the person making those footprints.”

Like almost any episode of NOVA, this one illuminates the exciting twists and turns of scientific discovery. “We take people on a journey though the challenges of trying to understand the past,” said Cort.

“We’re not at the end of this story,” said Schmidt. “I’m certain there will be more studies that could push the date of human life on North America back even further.”