More than 10,000 years ago, a woman or young man—a toddler balanced on one hip—set out on a harried trip northward through what is now White Sands National Park, New Mexico. Rain may have pelted the traveler’s face as their bare feet slid on the mud. They paused to briefly set the toddler on the ground before pressing on; a wooly mammoth and giant sloth ambled across their freshly laid tracks. Several hours later, the traveler followed the same route south, this time empty-handed.Now, a team of scientists have documented nearly a mile of fossilized footprints from the out-and-back venture—the longest human trackway of its age ever found. “I’ve never seen anything quite like it,” says Chatham University’s Kevin Hatala, an evolutionary biologist who was not part of the study team.The trackway consists of more than 400 human prints, including several tiny child prints, as described in a new study published in Quaternary Science Reviews. By analyzing the shape, structure, and spread of the tracks the research team unveiled an intimate portrait of one ancient person’s walk across the landscape, right down to their toes slipping on the slick surface.