Why walk across the planet for seven years? Journalist and National Geographic Fellow Paul Salopek is retracing the migratory path of humankind, from its origins in Ethiopia to the tip of South America. Just as early humans did, he's making this epic journey on foot. Read Paul Salopek's article—the first in a series—in National Geographic magazine online: ngm.nationalgeographic.com/2013/12/out-of-eden/salopek-text Watch videos from the worldwide walk: www.youtube.com/watch?v=Fk8DjvwJjLg www.youtube.com/watch?v=91rVcZihfzY See where Paul is now, and get walk updates: goo.gl/aGa1Wk