The juvenile mandible of the modern Japanese has a lower symphysis than that of the prehistoric Jomon, while the adult symphysis is conversely higher in the modern Japanese. This cannot be explained from population differences in masticatory environments. As an alternative factor that may influence symphyseal height, we examined tooth crypt size and placement patterns in the skeletal growth series of the two populations. Results showed that although the Jomon mandible had larger bicanine breadth than in the modern Japanese during growth, the modern Japanese has faster growing anterior teeth that became larger than those of the Jomon by the time of eruption, necessitating greater space. This is expressed as the faster growth rate of anterior alveolar height in the modern Japanese, measured as corpus height above the mandibular canal. Canine eruption distance and root length were greater in the modern Japanese than in the Jomon, corresponding to the increased difference of anterior corpus height between the two populations after canine eruption. However, the influence of tooth root length on anterior corpus height during later growth cannot be evaluated by this study. The present study suggests that the size and spatial dispositions of the developing anterior teeth have significant effects on symphyseal dimensions of the mandible until the time of tooth eruption.
There is evidence of a relationship between tooth size and tooth agenesis in human populations, with a tendency for reduced tooth size in individuals with missing teeth. The aim of this study was to analyze the size of remaining teeth (mesiodistal crown diameters) and their variability in individuals with varying degrees of severity of congenitally missing teeth. Tooth crown diameters were recorded from 100 dental plaster casts of Japanese males. Subjects were divided into three agenesis groups: group A had one missing tooth per individual, group B had two missing teeth per individual, and group C had three or more missing teeth per individual. For comparison, tooth size data were used from a previously studied sample of Japanese males who did not have any congenitally missing teeth. Group A displayed the largest mesiodistal crown size dimensions for all maxillary and mandibular teeth, followed by group B, and then group C. In comparison with the reference data, when only one or two teeth were missing, the remaining teeth tended to be larger, but when there were three or more missing teeth, the remaining teeth tended to be significantly smaller throughout the dentition. In terms of tooth size variability, dental dimensions in the agenesis groups were generally more variable compared with those in the reference sample. This tendency was most pronounced in the group with the greatest number of missing teeth. Although there was a tendency for the size of the remaining teeth to be more reduced as the number of missing teeth increased, tooth size in individuals with only one or two teeth missing was generally larger than in a control group with all 32 permanent teeth, suggesting that the relationship between tooth size and dental agenesis may be more complicated than previously thought, perhaps due to local compensatory interactions affecting the size of teeth.
Using Mahalanobis’ generalized distance for odontometric data and Smith’s mean measure of divergence for nonmetric dental data, interpopulation similarities between four local Ainu groups from Sakhalin Island and Hokkaido, as well as their supposedly ancestral and neighboring populations, were analyzed. In this study, multidimensional scaling and multidimensional plots by Andrews were applied to the distance matrices to visualize the intergroup relationships. The results obtained reconfirm the dental association between the prehistoric Jomon and the recent Ainu. However, the diversity of the recent Ainu in Hokkaido is not necessarily accommodated in a single regional populational lineage, the Jomon. The present findings also suggest that admixture between the immigrants from Northeast Asia as represented by the Okhotsk culture people and the indigenous inhabitants in Hokkaido during the 5th–12th centuries AD may in part have contributed to the formation of the physical characteristic of the recent Ainu. In particular, the female Okhotsk culture sample shows closer affinity to the northeastern Hokkaido and the Sakhalin Ainu in some of the analyses presented in this study. Such findings are compatible with those obtained by craniometric analyses, supporting the hypothesis of higher migration rates among females than among males due to patrilocality or the shorter matrilineal generation interval.
The practice of castrating men is an ancient one. Eunuchs have served as guards to harems and as palace chamberlains for many early courts, but details about their lives are often hazy or shrouded in secrecy. Although the changes wrought to their physical appearance from castration are well-documented, little is known about the magnitude of the skeletal changes resulting from the loss of sex hormones associated with the procedure. Such a loss of hormones, especially before puberty, affects skeletal growth and development and may result in early osteoporosis as well as impacting quality of life. The burials of two eunuchs from the Ming Dynasty (1368–1644 AD) of imperial China provide an opportunity to examine the consequences of castration upon the human skeleton. These eunuchs may have been castrated at different periods in their lives. One eunuch appears to have been castrated before the development of secondary sexual characteristics; the delayed epiphyseal closure accompanying androgen deficiency may account for his long limbs. Skeletal evidence also sheds light on the lives of these eunuchs, including their oral health, history of childhood stress, and activity patterns.
This study was designed to identify possible craniofacial measurements that have an influence on the cephalic index (CI) of Japanese adult females. The total sample used in the current study consisted of 832 healthy Japanese adults. The subjects were all of Japanese birth and ancestry. The age range of the subjects was between 18–25 years. Eight craniofacial measurements were taken: head length, head breadth, head height, head circumference, minimum frontal breadth, bizygomatic breadth, bigonial breadth, and morphological face height. In addition, stature and body weight were also measured. All measurements were taken by one observer from 1998 to 2001. The CI was calculated from head length and head breadth. Using multiple regression analysis, a variance inflation factor (VIF) demonstrated that there was no evidence of a multicollinearity problem among the variables when CI was considered as a response variable. The coefficients of the regression line demonstrated that there was a significant positive relationship between the CI and minimum frontal breadth (P < 0.01), bizygomatic breadth (P < 0.01) and head height (P < 0.05), while a negative relationship was found between the CI and morphological facial height (P < 0.05) and head circumference (P < 0.01). Moreover, the coefficient and odds ratio of the logistic regression showed that minimum frontal breadth (P < 0.05), bizygomatic breadth (P < 0.01), and head height (P < 0.05) were more likely in the round-headed group, while morphological facial height (P < 0.05), head circumference (P < 0.01), and stature (P < 0.05) were less likely in the round-headed group. Stepwise regression analysis showed that with respect to the CI, the best predictor variables were bizygomatic breadth, head circumference, minimum frontal breadth, morphological facial height, head height, and stature. These results suggest that most of the craniofacial variables measured appear to influence the CI of Japanese adult female students.
This article analyzes the changes in the distribution of body mass index (BMI) among college students aged 19–22 in Shandong, China from 1985 to 2005. In the past 20 years, the P50 (percentile 50) of BMI increased, from 20.44 kg/m2 in 1985 to 21.00 kg/m2 in 2005 for males, and from 19.97 kg/m2 in 1985 to 20.42 kg/m2 in 2005 for females. The proportion of overweight or obese (defined as BMI ≥ 25 kg/m2) increased from 1.35% in 1985 to 7.17% in 2005. Overweight and obesity among college students has become a serious public health problem. Comprehensive evidence-based strategies of intervention should be introduced, including periodic monitoring.
The Seiyokan site is located in Kamakura, Japan, and has yielded 91 human skeletons belonging to the 14–15th centuries AD. The purposes of this study are to examine the human crania from the archeological site at Seiyokan, to analyze the presence, distribution, and variability of their weapon-related traumas, and finally to better understand violence in medieval Japan from osteological evidence. The results demonstrate that the traumas on the crania have morphological features consistent with human-induced cut marks. The presence of cut marks on the Seiyokan crania, which strongly suggests the prevalence of violence in medieval Japan, is in accord with the historical background—that a militarily organized society was founded by force and that the rise to political power of the warrior class and the establishment of a military government resulted in continuous disturbances, armed conflicts, and violent death.
Permanent tooth emergence was examined in a sample of 114 Japanese children (63 girls and 51 boys) born in Tokyo in 1914 and 1924. Subjects were enrolled as young infants from households spanning a wide range of socioeconomic conditions, without regard to parental income or occupation. The children were prospectively examined up to age 20 years with observations of permanent tooth emergence recorded to the nearest two or three months. Parametric logistic-survival analysis was used to estimate the distribution of tooth emergence and, simultaneously, an agenic proportion. The effects of infant and childhood health status (good, medium, poor), breastfeeding type (full, partial, not), child’s sex, and birth cohort (1914, 1924) were modeled on the hazard of permanent tooth emergence and the fraction of agenic teeth. Controlling for other covariates, males exhibited a shorter time to emergence for three (PM1, PM2, M3) of the 16 permanent teeth, compared to females. Breastfeeding significantly affected time to emergence for seven teeth (I1, M1, M2, I2, PM1, M1, M2), although the direction of the effect was not consistent among teeth. Poor infant health consistently delayed emergence relative to children in good health for the earliest emerging teeth. Children of medium or poor child health showed delayed emergence for six permanent teeth (I2, PM2, M1, I2, PM1, M3). The strongest and most consistent relationship was a delay in emergence for children born in the 1914 cohort. This cohort effect may reflect changes in health resulting from declining socioeconomic conditions in Japan during this period. The probability of a tooth being agenic was generally unaffected by infant and childhood health status, breastfeeding type, child’s sex, or birth cohort.
An extended burial of a young adult female was recovered from Late Pleistocene deposits along the Narmada River in Rampura, Narmada District, Gujarat, Western India in 2005. Radiocarbon dating of the skeleton indicates that the individual was buried between 324 and 60 years ago, with the mean estimation placing the year of death at 1817. Osteological analyses indicate that the individual is a female who died between the ages of 16 and 21 years, and morphometric analyses of the cranium place show affinity with the community of South Asians known as adivasis or ‘tribals.’ Analyses of the dentition of the young woman, who had pink teeth, could shed light on the possible cause of death. If this condition was not brought on post-mortem due to the wet soil conditions, it could reflect death by drowning. Although burial in general is rare in India (where cremation is typically practiced among Hindus) and burials outside of cemeteries are uncommon for the non-Hindu communities, a few local tribal groups are known to bury their dead. Comparative cross-cultural analyses of death rituals among India’s tribal populations in conjunction with an analysis of the specimen itself are combined to infer the population affinity of this individual. This specimen provides rare first-hand information on the burial practices of India’s tribal groups.