A new archaeological method to reveal the arrival of cereal farming: Development of a new method to extract and date of carbonised material in pottery and its application to the Japanese archaeological context

Abstract

Cereal farming, such as rice and foxtail and broomcorn millets, originated in mainland China. When such farming was introduced to surrounding areas of East Asia remains an archaeological mystery because of scant data on carbonised grains from the initial farming stage. Even when data are sufficient, there remains uncertainty in whether the grains coincided with the accompanying pottery type. This problem can be overcome by examining grain impressions in pottery fabric through the use of silica casts, which allows us to obtain data on the introduction of crops without contamination, even from archaeological sites where flotation was not conducted or carbonised grains have not been detected. Thus, the estimated age of the grain impression can be assessed through the associated pottery type. However, where the chronology of pottery types is not clearly established, and chronological variations exist over a wider geographic area, this method alone cannot establish the first appearance of grains. We thus propose a new method that uses X-ray equipment to search for carbonised grains embedded within earthenware and directly date these grains to overcome the aforementioned limitation. We apply this method to a key site, the Etsuji (江辻) site, Fukuoka, Kyushu Island, to examine the introduction of rice and millet agriculture to Japan. The results push back the dating of the Etsuji Phase and the introduction of cereal farming by about 100 years to 1190–820 cal BC. This method could make a significant contribution to the study on the introduction of agriculture across East Asia, where similar problems with floating pottery typologies are encountered.