Comparative study of vertical sections of the Jomon and modern Japanese mandibles

Abstract

The purposes of this study are to compare the characteristics of mandibular internal structures between Neolithic Jomon and modern Japanese, and to investigate the relationship between internal structures of the mandible and the standing position of the teeth in both populations with the use of CT scanning. The data for this study were obtained from 40 male Japanese and 39 male Jomon dry adult skulls housed in the Department of Anthropology and Prehistory, the University Museum of the University of Tokyo. For each specimen, a lateral radiograph of the skull and four CT scan sections of the mandibular body were available. The lingual inclination of mandibular molars of Jomon was weaker than that of modern Japanese, and mandibular cortical bone of Jomon was thicker than that of modern Japanese mainly because Jomon had strong masticatory function. Although the dental arch breadth of Jomon was larger than that of modern Japanese, there was no significant difference in the mandibular body breadth in molar regions. It was suggested that overall size of mandibular body of Jomon was almost the same as that of modern Japanese, but the larger dental arch breadth resulted from upright position of molars.