Adult Jomon femora are known to be more robust with mid-diaphyseal cross sections that are more elongated anteroposteriorly than in the modern Japanese. In the present study, we compared femoral midshaft cross-sectional geometric properties between prehistoric Jomon hunter-gatherers and modern Japanese from the seventh fetal month to 17 years of age. The cross-sectional properties reflecting mechanical strength and shape (e.g. cortical bone area, medullary cavity area, area moments of inertia, representative indices) were measured using micro-computed tomography on 58 Jomon and 73 modern Japanese femora. Results showed that the Jomon midshaft cross sections are significantly larger, more robust, and stronger under mechanical loading than those of the modern Japanese throughout the examined fetal to subadult periods. The consistently greater robusticity of the Jomon femur was caused by (1) greater bone diameter and mass established at least by late fetal life, (2) lower endosteal bone resorption rates from toddler through subadult ages, and (3) greater subperiosteal bone expansion after around puberty. In both Jomon and modern Japanese, the femoral midshaft cross-sectional shape changes through growth, on average, from near-circular to slightly anteroposteriorly elongated. This was seen to be exaggerated in the Jomon midshaft by bone distributional changes that involve enhanced posterior projection of the shaft corresponding to the well-known femoral shaft pilaster. The results also demonstrated that the fetal to infant Jomon femoral midshaft cross sections tend to be broader mediolaterally than those of the modern Japanese, possibly contributing to the adult subtrochanteric platymeric (mediolaterally broad) cross-sectional shape of the Jomon proximal femoral shaft. Our findings suggest that complex interactions of population-specific genetic background, differential response to activity level and/or mechanical load, and elevated levels of activity/load and muscle hypertrophy appear to have caused the Jomon condition of a comparatively robust femoral diaphysis.
Individual dietary differences (e.g. sex, age, period, and region) among townspeople during the Edo period are unclear, although the historical literature describes the general dietary menu. We applied carbon and nitrogen stable isotope analyses to 103 adult human skeletons excavated from the Ikenohata-Shichikencho site of the Edo period (late 17th to late 19th century AD) in Japan to investigate individual dietary differences among townspeople in the city of Edo. The mean carbon and nitrogen isotope ratios of Ikenohata townspeople were −19.7 ± 0.4‰ and 10.8 ± 0.7‰, respectively, which suggests that C3-based terrestrial foods, freshwater fish, and marine fish were their main dietary protein sources. Intra-population comparisons indicated no significant difference among individuals of different sexes, age categories, and chronological periods, with the exception of a sex difference in carbon isotope ratios (0.37‰) during the Middle–Late period (last half of 18th century). Comparison of the Ikenohata data with the results of previous studies revealed significant isotopic differences in skeletal populations of the same social class (up to 1.33‰ for nitrogen) and same Edo city (up to 1.64‰ for nitrogen). Although these differences were relatively small in terms of stable isotope ecology, dietary food sources for people during the Edo period would differ to some extent by their social class and geographic region of residence.
In the eastern Pampa–Patagonia transition, hunter-gatherer groups experienced a series of changes in social organization (e.g. subsistence, mobility, and demography) during the Late Holocene (c. 3000–250 years BP), mainly in the last c. 1000 years. In this context, some biological aspects, including health, might have also been modified. The aim of this paper is to present a review and synthesis of a recent pathological analysis of hunter-gatherer skeletons from the lower basin of the Colorado River (Argentina) during the Late Holocene. The sample includes 94 individuals from six archaeological sites. Bone and dental pathologies (e.g. osteoarthrosis, systemic stress, bone infections, trauma, caries, periodontal disease, antemortem tooth loss, and dental calculus) were considered. The results show low frequencies in most of the bone and oral pathologies. Trauma, infectious, and systemic stress processes did not show large variation among samples from the Late Holocene. However, increasing prevalence of dento-alveolar lesion and osteoarthrosis were observed in samples from the final moments of this period (c. 1000–250 years BP). These results are discussed taking into account the archaeological model proposed for the eastern Pampa–Patagonia transition, which suggests social transformations and reorganizations during the last 1000 years.
Using lateral cephalometric images, we compared the skeletal and soft tissue configurations of Ryukyuan and mainland Japanese females. We collected lateral cephalometric images of 30 females each from Okinawa Island and mainland Japan. Sixty landmarks were plotted on each image. Then, based on the coordinates of the landmarks, 68 distances and 34 angles were calculated according to orthodontic and anthropometric methods. We confirmed that the Ryukyuans have a smaller height in the upper and midfacial region than the mainland Japanese. Moreover, our findings indicate that, compared with the mainland Japanese females, the Ryukyuan females clearly have the following features: (1) a shallower mandibular notch, (2) an anterior-inclined symphysis of mandible, and (3) a smaller depth from upper lip to incisors. We also found that an anterior-inclined mandibular corpus and incisors are associated with a smaller distance between the surfaces of the upper lip and teeth and with a more protruded lip shape.
Prognathism in the human facial skeleton is generally divided into two types: alveolar and facial. The degree of alveolar prognathism has conventionally been evaluated using the alveolar profile angle, defined on the basis of the line through the nasospinale and prosthion and the Frankfort horizontal (FH). Previous examinations of Japanese crania from the protohistoric Kofun period (c. 300–700 AD) to the modern period have established that the medieval (c. 1200–1600 AD) Japanese possessed the strongest alveolar prognathism. However, the nasospinale is an ambiguous landmark that is difficult to determine. Moreover, it has been suggested that the alveolar profile angle itself is problematic for quantifying alveolar prognathism. Here, we devised a new method for evaluating each type of prognathism independently and investigated temporal changes in the Japanese population using three-dimensional (3D) coordinate landmark data collected with a 3D contact digitizer. Facial prognathism was quantified using an obtuse angle, termed the midfacial protrusion angle, created by a line that runs through the nasion and subspinale with the FH. Alveolar prognathism was evaluated using a reflex angle, named the alveolar protrusion angle, formed between the nasion–subspinale and subspinale–prosthion lines. An analysis of 66 male crania derived from the northern Kyushu and Yamaguchi (westernmost part of Honshu) region showed no significant change of the alveolar protrusion angle over time from the Kofun period to the modern period. In contrast, the midfacial protrusion angle increased from the Kofun period to the medieval period and then decreased in the modern period. These results suggest that the strongest facial prognathism was exhibited in the medieval period. Previous results, which suggested that alveolar prognathism was strong in the medieval Japanese, may have been significantly affected by facial prognathism.