Cockroaches in the Jomon Period show same distribution as in modern Japan: Estimation by Kumamoto University based on impressions in pottery

By the mid to late Jomon period, Japanese cockroaches had already established the habitats seen today. A research group led by Professor Hiroki Obata at Kumamoto University has identified cockroach species using impressions of cockroach egg cases left on Jomon pottery. The results were published in the Journal of Archaeological Science: Reports.

Professor Obata and his colleagues have been researching the types of plants cultivated, and the types of household sanitary pests present during the Jomon period. Their method involves the use of impressions left in pottery to search for traces of organisms from that time period. In 2016, the team discovered indentations of cockroach egg cases on the surface of Jomon pottery at the Motonobaru site in Miyazaki City, Miyazaki Prefecture, Japan.

There are about 50 known species of cockroaches in Japan, of which about 10 are so-called house cockroaches that enter houses and buildings. Currently, the Japanese cockroach, which lives mainly in eastern Japan, has been identified as an indigenous species because it appears in documents from the Heian period. However, most other species are considered to be non-native species originating from overseas, mainly Africa.

The species identified from the egg casing impressions at the Motonobaru site were from the Smokybrown cockroach, which is mainly found in western Japan. This finding led to the idea that this species, which had previously been presumed to have originated in southern China and entered Japan during the Edo period, might have originated in Japan.

During their study, the team performed detailed morphological comparisons and a close examination of the ecology and distribution of each species on newly detected impressions found in pottery at the Kamitashiro site in Ebino City, Miyazaki Prefecture, the Komaki site in Kanoya City, Kagoshima Prefecture, and the Sekiguchi site in Hokuto City, Yamanashi Prefecture. By comparing these impressions with egg casings from modern cockroaches, the team identified the egg sheaths from the Kagoshima and Miyazaki Prefecture sites as belonging to the Smokybrown, and those from the Yamanashi Prefecture excavation as belonging to the Japanese cockroach.

These results confirm that the Smokybrown cockroach, which was thought to have been introduced from southern China during the Edo period, is a species native to Japan that already existed during the Jomon period. It also indicates that the distribution of the main cockroach species in modern Japan, the Smokybrown cockroach in western Japan and the Yamato cockroach in eastern Japan, may have been established between 5300 and 4000 years ago. This is a significant research result that casts doubt on the conventional theories about the history of how house cockroaches came to establish themselves in Japan.

Journal Information
Publication: Journal of Archaeological Science: Reports
Title: The Jomon people cohabitated with cockroaches - The prehistoric pottery impressions reveal the existence of sanitary pests
DOI: 10.1016/j.jasrep.2022.103599