Fossil human footprints found in 1998 high in the mountains of Tibet, in what was once the mud of a natural hot spring, have now been dated to between 7,400 and 12,600 years ago, making the ancient site of Chusang the oldest known permanent base of people on the Tibetan plateau.
     The 19 human handprints and footprints were found near Chusang, a village known for its hydrothermal springs, located on Tibet's central plateau at an elevation of about 14,000 feet (4,300 meters) above sea level.
     A previous attempt to date the prints estimated that they were 20,000 years old, but the region's complex geology prompted the new research, which combined three different dating techniques: thorium/uranium dating, optically stimulated luminescence, and radiocarbon dating of microscopic plant remains.
     The three methods gave the researchers a broad time range, showing that the prints could have been made anywhere between 7,400 years ago and 12,600 years ago. Genetic studies have suggested that a permanent population on the high central plateau dates to at least 8,000 to 8,400 years ago. Previous analyses of other sites suggested that the plateau's earliest permanent human residents had settled there no earlier than 5,200 years ago. Older known human camps exist in the region, dating to between 9,000 and 15,000 years ago, but they were likely short-term, seasonal sites.
     Round-trip travel times from a lower-elevation base camp to Chusang 11,500 years ago would have taken anywhere from 28 to 47 days, and crossed the eastern Himalayan range - impassable for much of the year. Another, more passable route would have taken 41 to 71 days. The remote location has led the researchers to conclude that the people would have been permanent residents.
     Chusang was likely a permanent settlement before people began using agriculture in the area. About 11,500 to 4,200 years ago, the region was wetter and more humid than it is today. Study co-leader and assistant professor of geology at the University of Innsbruck, Michael Meyer says: "There is a chance that there are older sites up here. I think we have to keep exploring."

Edited from LiveScience (5 January 2017)