How and when people first set foot in the Americas is one of the enduring mysteries of human history. Most archaeologists now agree people lived in the Americas before Clovis-style tools—once thought to be linked to the first Americans—appeared about 13,000 years ago. Last year, for example, researchers reported human footprints in White Sands National Park in New Mexico, dating back 23,000 years.
Many scientists pursuing the question acknowledge that too often, they have not included Native Ame...