High-Altitude Occupations and Early Trans-Tibetan Interaction: Evidence from the Piluo Site

FENG Yue1*, ZHENG Zhexuan2, TAN Peiyang2, and ZHANG Jiafu3

The Tibetan Plateau has long been considered as a major obstacle for the dispersal of early hominids along the southern migration route, leading to the isolation of East Asian Palaeolithic populations and technological stasis before the arrival of Homo sapiens. Located on southeastern Tibetan Plateau at an elevation of 3750m, the Piluo Site yielded nine sequential cultural layers dated from MIS 8 to MIS 3, marking the oldest and longest occupational sequence of high altitudes. Based on stratigraphy, OSL dates, paleo-environmental reconstruction and techno-complexes of lithic artifacts, the developmental trajectory can be further classified into four phases. Phase one (layers 7-10, MIS8) was represented by simple core-and-flake industry exploiting sandstone pebbles, indicating that the earliest inhabitants of the Plateau were likely migrated upstream from Southeast China. Phase two (layers 5-6, MIS7) witnessed the first emergence of typical handaxes and cleavers, which were connected with Late Acheulean complexes discovered in South Asia, and they were also the Acheulean at the highest elevation worldwide known so far. Bifaces in phase 3 (layers 3-4, MIS 6) increased in number but were miniaturized in size, resembling Middle Paleolithic in South Asia. Phase 4 (layer 2 and ETG 1, MIS 5-3) was characterized by small-sized quartz flake tools, possibly related to southward migration of the Denisovans from the northeast Tibetan Plateau. This sequence revealed that various populations with different technological traditions have occupied the high-elevation areas, and their interactions provided crucial evidence to reevaluate human dispersal and cultural exchange along the southern migration route.