Ancient starch in China

Today I read the following paper. It discusses about starch residues on archaeological stone tools.

• Yang, XiaoYan, JinCheng Yu, HouYuan Lü, TianXing Cui, JingNing Guo, and QuanSheng Ge. 2009. Starch grain analysis reveals function of grinding stone tools at Shangzhai site, Beijing. Science in China Series D: Earth Sciences 52 (8): 1164-1171.