Sex differences of dental pathology in early modern samurai and commoners at Kokura in Japan.

So-called "Ohaguro", teeth blackening, in the married females was a general custom regardless of class in the early modern period. As a result, Ohaguro was thought to have enhanced the acid resistance of tooth substance and tightened gingiva and prevented tooth morbidity due to periodontal disease. For investigation into the influence of Ohaguro, the skeletal remains of early modern samurai and commoners at Kokura were examined for differences in the dental pathology based on sex. Though females from archeological sites have significantly more carious teeth and antemortem tooth loss (AMTL) than males in the previous studies, the prevalence of caries and AMTL in males was higher than in females among the early modern samurai and commoners in Kokura. The efficacies of Ohaguro may influence the good dental health of females. On the other hand, as females were considered inferior to males under the feudal system in Japan, males, including children, might tend to consume more nutritious foods compared to females. However, those foods are certainly not better with regard to dental health, since those foods are more highly cariogenic. These factors may have caused higher caries and AMTL prevalence among males compared to females in early modern Kokura.

Mitochondrial DNA analysis of Yayoi period human skeletal remains from the Doigahama site.

We analyzed the mitochondrial DNA extracted from 14 human skeletal remains from the Doigahama site in Japan to clarify the genetic structure of the Doigahama Yayoi population and the relationship between burial style and kinship among individuals. The sequence types obtained in this study were compared with those of the modern Japanese, northern Kyushu Yayoi and ancient Chinese populations. We found that the northern Kyushu Yayoi populations belonged to the groups that include most of the modern Japanese population. In contrast, most of the Doigahama Yayoi population belonged to the group that includes a small number of the modern Japanese population. These results suggest that the Doigahama Yayoi population might have contributed less to the formation of the modern Japanese population than the northern Kyushu Yayoi populations. Moreover, when we examined the kinship between individuals in the Doigahama site, we found that the vicinal burial of adult skeletons indicated a maternal kinship, although that of juvenile skeletons did not. The vicinal burial style might have been influenced by many factors, such as paternal lineages, periods and geographical regions, as well as maternal lineages. In addition, skeletons considered to be those of shamans or leaders had the same sequence types. Their crucial social roles may have been inherited through maternal lineage.

Dental morphology of the Dawenkou Neolithic population in North China: implications for the origin and distribution of Sinodonty.

We compare the incidence of 25 nonmetric dental traits of the people of the Neolithic Dawenkou culture (6300-4500 BP) sites in Shandong Province, North China with those of other East Asian populations. The Dawenkou teeth had an overwhelmingly greater resemblance to the Sinodont pattern typical of Northeast Asia than to the Sundadont pattern typical of Southeast Asia. Multidimensional scaling using Smith's mean measure of divergence (MMD) statistic place the Dawenkou sample near the Amur and the North China-Mongolia populations in the area of the plot indicating typical Sinodonty. The existence of the Sinodont population in Neolithic North China suggests a possible continuity of Sinodonty from the Upper Cave population at Zhoukoudian (about 34000-10000 BP) to the modern North Chinese. The presence of Sinodonty in Shandong Province shows that the Japan Sea and East China Sea were strong barriers to gene flow for at least 3000 years, because at this time the Jomonese of Japan were fully Sundadont. In addition, we suggest that the descendants of the Dawenkou population cannot be excluded as one of the source populations that contributed to sinodontification in Japan.