The Relationship between Immigration and the Prevalence of Dental Caries in the Yayoi People

摘要

Skeletal remains of the Yayoi people, who had been excavated from Northern Kyushu and Yamaguchi Prefecture in Japan, are thought to be largely the descendants of continental immigrants. Carious ratios of the Yayoi people are higher than those of the Jomon people and their descendants. Results of the present study showed that, in frequency of carious lesions and in state of dental attrition, the Yayoi people of the Northern Kyushu and Yamaguchi regions were different. Caries ratios of the Yamaguchi Yayoi people were high in both adolescent and elderly groups. But, although caries ratio of the elderly Yayoi people of the Northern Kyushu region was high, that of the adolescent group of Northern Kyushu was low and close to that of the Jomon people. Dietary custom is thought to be the cause of this difference. The location of site is also different between the two Yayoi period samples. Moreover, there are some differences in skeletal shape between them. Therefore, the main subsistence of the Northern Kyushu Yayoi people might have been different from that of the Yamaguchi Yayoi people. Chinese skeletal remains whose carious teeth ratio was as high as that of the Yayoi people of the Northern Kyushu region and Yamaguchi Prefecture have not yet been found in any population examined by the present or other studies. Taking these findings into consideration, we assume that it is highly possible that the carious teeth ratio increased after the ancestors of the Yayoi people immigrated to Japan.