Plant utilization at the Jiangxigou site during the middle Holocene

Agricultural activities on the Qinghai–Tibetan Plateau (QTP) are difficult due to the hostile environment. Despite the difficulties, recently early agriculture has been documented by Holocene plant remains on the QTP. The details of the time, place, and mechanisms of agricultural origin as well as the evolution of agriculture on the QTP are still lacking. The Jiangxigou site (JXG2) contains artifacts dominated by microliths from the early to middle Holocene and provides important information on agricultural origins and evolution of prehistoric culture on the QTP. Here we report ancient starch grains and pollen extracted from ceramics and deposits excavated from each layer. The starch remains include 21 grains identical to starches from millets (Setaria spp. and Panicum spp.), probably including 24% domesticated foxtail millet (Setaria italica), indicating that humans at 3000 m above sea level (masl) in the northeastern margin of the Qinghai–Tibetan Plateau (QTP) began to use millets ca. 5600 cal BP. Considering archeological evidence, the reasons for millet utilization by plateau residents may be associated with the expansion and influence of the Yangshao culture via the Loess Plateau.