A Bedouin-origin clan with extremely high fertility in south Jordan sedentarized in a village in 1948. In this paper, based on our genealogical-demographic data collected from this clan, we elucidate the long-term demographic change that this clan has undergone. Our results highlight differences in fertility indicators among the early (1950–1969), middle (1970–1989), and late (1990–2004) periods. In particular, the total marital fertility rate (TMFR) was 4.756, 9.852, and 9.146, respectively, and the total fertility rate (TFR) was 3.589, 7.214, and 5.189, respectively. Taking age-specific indicators into account, the increase in TFR or TMFR from the early to the middle periods was attributable to increased rates of childbirth among middle-aged and older women, presumably associated with improvements in maternal nutrition and increased demand for children as agriculture labor, while the decrease in TFR from the middle to the late periods was caused by a delay in females’ age at marriage and an increase in the number of unmarried females. The fertility of this clan has been high, especially in the late period, and it is estimated that its population will double by 2030, implying the urgent necessity to reduce fertility to prevent overpopulation that threatens the people’s subsistence adaptation.
The strict class system in place during the Edo (early modern) period in Japan is thought to have encompassed customs that differed between the samurai (ruling class) and commoners. This study found that in samurai children, deciduous caries occurred only in maxillary incisors at 0.5–2 years of age and did not occur in the mandibular incisors and canines at 3–5 years of age. Conversely, in commoner children, deciduous caries occurred in all maxillary teeth and mandibular molars at 0.5–2 years of age and in all maxillary and mandibular teeth at 3–5 years of age. In commoner children, deciduous caries was seen in tooth types that have a low incidence of deciduous caries in modern Japanese. The present results show that deciduous carious lesions appear earlier and more frequently in the commoner children compared to the samurai children, probably because of differences in lifestyle between the two groups. There was no significant difference in the incidence of enamel hypoplasia in the deciduous dentition between samurai and commoner children, suggesting that the two classes had broadly comparable nutrition. In our previous study using the same skeletal series, similar results between samurai and commoners were found with respect to caries and enamel hypoplasia prevalence of the permanent dentition. Many of the samurai adults had slick polished teeth, which we believe were caused by regular brushing of the teeth in the samurai class. Such a custom might have functioned to prevent dental caries not only in the permanent dentition, but also in the deciduous dentition. Thus, oral hygiene practices in the samurai class are thought to have functioned to prevent dental caries not only in adults but also in children.
The frequency and morphology of mandibular tori and the correlations between their development and environmental factors (number of teeth, degree of crowding, degree of dental attrition) were examined in plaster casts of present-day Japanese dental patients and students. A total of 224 patients (118 males aged 13–77, average age 50; 106 females aged 15–81, average age 49) and 113 students (60 males aged 17–36, average age 20; 53 females aged 18–29, average age 19) were included in the examinations. Before the examinations, we defined a new torus grading system with four categories. There were no statistically significant differences between males and females and between the left and right sides in the distribution of torus classes and positions. Palpable tori were found in 76.6% of patients and 72.0% of students. Perceptible tori were found in 70.3% of patients and 58.0% of students. Tori were most frequently found below the first and second premolars. In students, the torus class and size negatively correlated with the degree of crowding and positively correlated with the degree of dental attrition. In patients, torus class and size positively correlated with the degree of dental attrition, the number of teeth, and age. From these results, we suggest that mandibular tori are promoted by masticatory stress and other factors correlated with age.
Population affinities and biological variation in human skeletal series associated with the Okhotsk culture from Hokkaido and Sakhalin Islands from the 5th to 12th centuries AD are investigated using 19 nonmetric cranial traits. The Okhotsk crania have a higher frequency of the supraorbital foramen than the Hokkaido Ainu and Jomon, while the frequency of the transverse zygomatic suture vestige in the Okhotsk is as high as in the Jomon. The mean measure of divergence between the northern and eastern Okhotsk cranial assemblages is small and insignificant. The method of Relethford and Blangero [Relethford J.H. and Blangero J. (1990) Human Biology, 62: 5–25] suggests that the eastern Okhotsk had a larger Rii value (distance from the centroid) and a lower observed variation than the northern Okhotsk, indicating that the eastern Okhotsk lost phenotypic variability. These results further reaffirm the affinity between the Okhotsk skeletal series and Northeast Asian series such as the Neolithic Baikalian and Amur. Finally, the results of analyses of nonmetric cranial variation demonstrate a close relationship between the Okhotsk, Ainu, and Jomon series that suggests that the Jomon and Ainu were closer to the Okhotsk than to other Northeast Asian series prior to any admixture.
This study investigates dental morphological variations among the modern inhabitants of Tanegashima Island and Okinawa Main Island of the Nansei Islands (Ryukyu island arc), which is the southern gateway of the Japanese archipelago. Temporal variations within Tanegashima Island and regional variations of the northern half of the Nansei Islands were used to study population history. The late Aeneolithic Yayoi to protohistoric Kofun populations (c. 0–700 AD) of Tanegashima was found to be similar to the native Japanese populations, such as the Neolithic Jomonese (c. 10000–300 BC) and Hokkaido Ainu; however, the modern population of Tanegashima was similar to the migrant Japanese populations such as the post-Jomon people (c. 300 BC–present time) of the Japanese main islands. Using statistically sufficient materials, this study confirmed that a substantial change had occurred from the prehistoric to the modern period in Tanegashima Island. It is suggested that temporal change occurred in Tanegashima over approximately 1000 years after substantial change (c. 300 BC) in the Japanese main islands. The delay in temporal change in Tanegashima indicates that dispersal of migrant populations from northern Kyushu to its southern end occurred at a time remarkably later than the northeastward dispersal of migrant populations to central Honshu Island. Furthermore, the geographical cline extending from North Kyushu to Okinawa Main Island via Tanegashima Island suggests southward gene flow from North Kyushu to the central Nansei Islands via the northeast end of the Nansei Islands.
A number of papers on the growth of Chinese children have been published in local journals in China in the Chinese language. However, we noticed that height and weight are the main focus of these studies. Because leg length relative to height is of interest in human biology, the current study focuses on the growth of this proportion. Two groups of Chinese children were investigated: 587 boys and 625 girls in Beijing in 1997 aged 6–18 years, and 579 boys and 615 girls in Xilinhot, Inner Mongolia, in 2005 aged 7–18 years. Height and leg length (iliospinal height) were measured, and the ratio of leg length to height was calculated for each child. Mean distance curves and spline-smoothed yearly increment curves were obtained. In order to clarify the difference between the two groups of Chinese children, data from Japanese children were adopted as a control. The Beijing children were taller than the Xilinhot children, but no difference was detected in leg length between them. The ages at ‘take-off’ and ‘peak’ obtained on the yearly increment spline-smoothed curve of height in the Xilinhot children boys were 1.2–1.8 years earlier, respectively, than those of the Beijing boys. In the girls, these two ages were almost the same in the two cities, although the ‘peak’ was 1.8 cm greater in the Xilinhot girls. Leg length in the boys was almost the same in both Beijing and Xilinhot. In the girls of the Xilinhot group, leg length was greater after puberty. Consequently, the ratio of leg length to height was greater in the Xilinhot children than the Beijing children. It is suggested, in China, that socioeconomic factors influence growth of height to a greater extent than growth of leg length, and that leg length and leg length relative to height might be controlled by a genetic factor.
An increasing number of studies determine endocranial capacity (ECC) digitally using serial computed tomographic (CT) scan data. However, the multiple causes of errors inherent in such measurements and the resulting degree of accuracy have not yet been fully examined. In the present study, five observers estimated the ECCs of two modern human crania by segmentation of CT data (voxel size 0.380 mm) and by means of the conventional millet seed method. The ECC estimations were much more consistent in the CT-based (technical error, TEM = 1.4 cc) than the millet seed (TEM = 11.8 cc) methods. The estimated capacities also tended to be larger in the latter, suggesting possible systematic bias. Next, the causes and degree of error in the CT-based method were examined. Error due to size calibration of the CT images was no more than 3 cc (± 1.5 cc) per 1000 cc. Errors involved in delineating the endocranial cavity were evaluated as follows. First, we adopted a segmentation routine in which a single global threshold value was applied to most of the volume, and then supplemented locally by more appropriate values in the regions where the global value was insufficient. We then estimated the potential error introduced by choosing a global threshold value. We found this to be within 5 cc (per 1000 cc). This error range increased to 7.5 cc (per 1000 cc), when using a lower resolution data set (slice thickness 1.14 mm). Another source of interobserver error involves the blocking of foramina and canals, which we estimated to be less than 2 cc (per 1000 cc). Adding these various effects, our investigations indicate that ECC estimations based on high-resolution CT data are accurate to within ± 5 cc per 1000 cc. Finally, we reevaluated the ECC of the Minatogawa 1 skull to be 1335 cc (with a probable range of 1327–1343 ± 5 cc), considerably smaller than the originally reported value of 1390 cc obtained by the millet seed method.
It is proposed that the so-called ‘protruding buttock’ figurines from Middle Jomon central Japan may be representations of steatopygia. The distribution of these figurines is associated with archaeological evidence for high population densities and possible intensive use of wild yams (Dioscorea japonica). Given the low fat content of these yams, it is suggested that nutritional stress in the diet of Middle Jomon hunter-gatherers of the Chubu highlands may be consistent with the fat accumulation on the buttocks apparently represented in the ‘protruding buttock’ figurines.