White Sands footprints provide unequivocal evidence that people were in the Americas at the height of the Last Ice Maximum, rather than some time after, as previously thought. This is a big problem for our understanding of the settlement of the Americas and the genetic makeup of Native Americans.
Using the DNA of modern Native Americans, scientists discovered that their ancestors arrived from Asia in several waves, some of which became genetically isolated. The cause of this isolation is not clear. Now our new footprint evidence provides an explanation, suggesting that the first Americans were isolated south of the North American ice cap, only to be joined by others when that sheet melted.
Our discovery could also reopen speculations on other archaeological sites in the Americas. One of them is the Chiquihuite cave in Mexico. Archaeologists recently claimed that evidence from this cave suggests humans occupied the Americas around 30,000 years ago – 7,000 years before people left White Sands footprints.
But the findings at Chiquihuite Cave are disputed by some, as stone tools can be difficult to interpret and tool-like stones can form through natural processes. Stone tools can also move between layers of sediment and rock. Fossil prints can’t. They are attached to a sleeping surface and thus provide more reliable evidence of exactly when humans left them.