Public Release: 

Humans occupied Tibetan Plateau thousands of years earlier than previously thought

American Association for the Advancement of Science

A new analysis of an archeological site in the high mountains of Tibet suggests that permanent residents may have set up camp thousands of years sooner than previously thought. Previous analyses estimated that the site's founding residents arrived about 5,200 thousand years ago, but now a more comprehensive analysis by Michael Meyer et al. suggests that it was inhabited, likely on a permanent basis, at least 7,400 thousand years ago, but perhaps as long as more than 12,000 years ago. Upon leaving Africa, humans effectively spread out across most of the Earth, but the timing of their arrival in the highest Himalyan ranges has been unclear. Among some of the best preserved sites for scientists to study is Chusang, a village perched in the central plateau more than 4,000 meters above sea level. The site, discovered in 1998, features 19 human hand- and footprints along the surface of a fossil travertine. In attempts to better date the village, Meyer and colleagues used three different techniques, including thorium/uranium dating of samples taken from and adjacent to the prints; optically stimulated luminescence (OSL) to determine the date of quartz crystals in the travertine; and radiocarbon dating on microscopic plant remains at the site. Their new estimated range for settlement at Chusang, between 7,400 and 12, 6700 thousand years ago, is more in line with results from some genetic studies, the authors note. As well, they highlight how difficult travel from this base camp must have been, with roundtrip routes to other sites likely taking dozens of days and being impassable for most of the year. Therefore, they emphasize that is it very likely that Chusang represents a permanent settlement, before agriculture took hold in the area. Permanent pre-agricultural peopling of the plateau may have been enabled by a wetter climate that prevailed in the region at the time, Meyer and colleagues suggest.

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