Discrimination of Cereal Residue Adsorbed by Pottery Based on Metabolomics

Cereal remains are common and important archaeological finds, providing crucial evidence for the origin and development of agriculture. Many previous studies have utilized one or several molecules as biomarkers to identify archaeological remains. However, there is a lack of systematic research on characteristic metabolites of common grains, especially of ancient varieties. The goal of this study was to derive a series of more species-indicative biomarkers using untargeted metabolomics as well as provide new insights into the identification of cereal remains excavated in archaeology. First, modern cereal, pottery and archeological samples were used for untargeted metabolomics to obtain plant metabolites. Then, statistical analyses were employed to screen candidate biomarkers. It was determined there are 73, 42, 138 and 58 metabolites representing broomcorn millet, foxtail millet, wheat and rice, respectively. Among the compounds mentioned above, 33 were found to be present in the archaeological samples from the Dongxiafeng site dating back around 3600 years. These 33 biomarkers would serve as characteristic elements for systematic clustering. The results indicated that among pottery sherds from the Dongxiafeng site, the most likely processed cereal is foxtail millet, and the least likely processed cereal is wheat. The theoretical calculated proportions of four grains are as follows: broomcorn millet 26%; foxtail millet 51%; wheat 18%; rice 5%. This aligns with the agricultural tradition in this region during the early Bronze Age, characterized by dryland farming with a focus on foxtail millet and broomcorn millet, while rice and wheat were also introduced.