The Tibetan Plateau,the world's "Third Pole",has an average elevation above 4,000 masl (meters above sea level) and an area of over 500 × 104 km2.It is the highest and largest plateau on earth and is very sensitive to global climate change [1,2].The cold,dry and hypoxic high-altitude environment of the plateau presents a major challenge to human survival.Therefore,the history and mechanisms of prehistoric human history on the Tibetan Plateau -from brief hunting expeditions to seasonal hunting-gathering and finally to permanent settlements-has attracted both general interest and substantial scientific debates [3-6].Archaeological studies indicate that humans probably first explored the plateau at the end of the late Pleistocene.They practiced intensive seasonal hunting-gathering from 15 ka BP [6],and permanently settled regions above 3,000 masl after 3.6 ka BP,which was facilitated by the development of an agropastoral economy [3].However,the early part of the human history of the Tibetan Plateau is still poorly documented,due to the lack of well-preserved archaeological sites and reliable dating results (Fig.1a).