The world of pottery admixtures

　As can be seen in the pottery of Fukui Cave, the mixing of parts of plants or fibres extracted from them into the clay used when making pottery had already begun in the Incipient Jomon period. This was done as a way to strengthen the pottery and thus to make it more lightweight. In the Ento-doki culture of the area from northern Tohoku to southern Hokkaido, pottery containing large amounts of plant fibres was made. Although this practice was not consistent, it is a phenomenon that can be seen during specific times throughout Japan.

Pottery from the Early Jomon period has been found mainly in the Hidaka region of Hokkaido that shows the impressions of cord (rope). Since the knots in the cord have been identified, we assume that nets of rope were probably used to make these marks. CT scanning of these particular sections of the pottery has allowed us to observe twisted cords and the knots in these cords in more three-dimensional images.

In addition, approximately 10,000 years ago, when wild rice began to be used in China, earthenware vessels with embedded rice in their husks appear, a practice that was to continue for quite a long time. The same type of impressions have been observed in pottery found at sites dated to the beginning of the Yayoi period. However, while these pottery pieces have millet and shiso (Perilla frutescens var. crispa) mixed into their clay, it remains unknown whether rice in its husk was mixed in the clay in China for the same purpose as in Japan. The presence of these types of by-products of grain processing that were used in pottery-making may indicate the spread of farming culture. This issue requires further study in the future.