|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1997 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1996 : ¥1,700,000 (Direct Cost : ¥1,700,000)
Temporal and regional variations of the various tooth sizes from the Initial Jomon period (about 10,000-6,000 BP) to the modern period in the Japanese inhabitants were investigated, using not only the maximum diameter of tooth crown but also a new measurement of tooth root-cervix uninfluenced by tooth attrition.
1. The migrant group from the Aeneolithic Yayoi period (about 2,300-1,700 BP) to the modern period has larger teeth than the native group such as the Jomonese and the Ainu.
2. The migrant Yayoi population or the protohistoric Kofun population has the largest teeth in the migrant group. The Yayoi or Kofun tooth size finally decreases toward the modern period, but the temporal decrease is accompanied with some fluctuations.
3. The tooth sizes of the Neolithic Jomonese and the native Yayoi population show some reduction toward the recent Ainu in the native group.
4. The most interesting result is a temporal change in a long term of the Jomon period. A temporal increase of the general tooth size was observed in the Initial-Early-Middle-Late-Final Jomon period (about 10,000-2,300 BP). The temporal change in the Jomon period shows an opposite change to the tooth reduction of a global tendency in the same period. There are some differences of the changing aspects between mesiodistal diameters and buccolingual diameters, and between crown diameters and root-cervix diameters. On the other hand, a temporal reduction of the ratio of the third molar to the other molar was shown, while the reduction might be contrary to the temporal increase of the general tooth size. Further research will be required in order to clarify the factor of the peculiar change in the Jomon period.