The first footprints were found in a dry lake bed in White Sands National Park in 2009. Scientists from the US Geological Survey recently analyzed seeds stuck in the footprints to determine their approximate age, ranging from about 22,800 to 21,130 years. The findings could shed light on a mystery that has long puzzled scientists: When did people first arrive in the Americas, after dispersing from Africa and Asia?
Most scientists believe the ancient migration came from a now submerged land bridge that connected Asia to Alaska. Based on a variety of evidence – including stone tools, fossil bones, and genetic analyzes – other researchers have proposed a range of possible dates for humans to arrive in the Americas, 13,000 ago. at 26,000 years or older.
The current study provides a more solid baseline for when humans were definitely in North America, even though they could have arrived even earlier, according to the authors. Fossil fingerprints are more indisputable and direct evidence than “cultural artifacts, modified bones or other more conventional fossils,” they wrote in the journal Science, which published the study Thursday.
“What we are presenting here is proof of a firm time and place,” they said.
Based on the size of the footprints, researchers believe at least some were made by children and adolescents who lived during the last ice age.
David Bustos, the park’s resource program manager, spotted the first footprints in ancient wetlands in 2009. He and others have found more in the park over the years.
“We knew they were old, but we had no way of dating the prints until we found some with (seeds) on them,” he said Thursday.
Made up of fine silt and clay, the footprints are fragile, so researchers had to work quickly to collect samples, Bustos said.
“The only way to save them is to save them – to take a lot of pictures and create 3D models,” he said.
Previous excavations in White Sands National Park have uncovered fossilized traces left by a saber-toothed cat, a terrible wolf, a Colombian mammoth, and other Ice Age animals.