A study from AAAS is shedding new light on the mystery of the timing of human migration into the Americas. While analyzing exposed outcrops of an ancient lake in White Sands National Park, New Mexico, the researchers discovered multiple human footprints that are 23,000 to 21,000 years old.  "Archaeologists and researchers in allied fields have long sought to understand human colonization of North America," wrote the researchers. "Questions remain about when and how people migrated, where they originated, and how their arrival affected the established fauna and...