Usewear and residue analyses of experimental harvesting stone tools for archaeological research

Chinese millets (Setaria italica and Panicum miliaceum), first domesticated in north China, were among the most important East Asian crops in the past. Previous studies have mainly focused on the morphological changes of millet grains for evidence of domesticity, but very few attempts have been made to understand the predomestication cultivation processes that predated morphological domestication and were likely involved with using certain harvesting methods. In order to develop methods for detecting evidence of this early stage of domestication we conducted a series of experiments cutting various wild and domesticated plants with stone tools, and analyzed the usewear traces and starch and phytolith residues on these tools. To evaluate the origins of the tool residues, we also extracted microbotanical contents from the stems and leaves of related plants with a focus on starch, and observed in-situ starches in leaves. The results show that stone tools with varying hardness and surface roughness used for harvesting cereals show diverse forms of polish and striations on their edges, and the confirmation of relatively large non-transient starch grains existing in stems/leaves provides a new opportunity for functional analysis of archaeological tools. This study proposes a multi-proxy approach to examine cutting tools for the evidence of cereal harvesting, particularly millets.