Tracking Humans’ First Footsteps in North America

Fossilized footprints, preserved in gypsum mud that hardened over time, are estimated to be 23,000-21,000 years old. NPS / Alamy Ancient human footprints, preserved in a dry lakebed at White Sands National Park in New Mexico, reveal remarkably vivid vignettes of life in the late Pleistocene: children jumping in puddles and splashing, a group of hunters stalking a giant sloth. The scientists studying these…