Using computed tomography, we examined the surface and internal morphologies of the upper face of people living on the Ryukyu Islands and mainland Japanese, focusing on the nasal root protrusion and eyeball position. The results showed that the nasal root protrusion on the surface was influenced by a combination of changes in both hard and soft tissues, such as skeletal nasal protrusion, eyeball recession, and skin thickness. The eyeball position became more posterior as the orbital cavity height and depth increased. Compared with people originating from mainland Japan, Ryukyu Islanders had a more prominent nasal root at both surface and skeletal levels, and a lower orbital rim relative to its internal height. However, a significant difference in the eyeball position and skin thickness was not detected. Therefore, the skeletal nasal root protrusion, not soft tissue configuration, is likely to account for the difference in the surface nasal root protrusion between the two populations. These findings will contribute to a better understanding of the association between hard and soft tissue configurations and the diversification of human facial features at the individual and population levels.
This paper provides a thorough description of humeral, ulnar, and radial specimens of the Nacholapithecus holotype (KNM-BG 35250). A spool-shaped humeral trochlea (and keeled sigmoid notch of the ulna) is a hallmark of elbow joint evolution in hominoids. In lacking this feature, the elbow of Nacholapithecus is comparatively primitive, resembling that of proconsulids. However, the humeroulnar joint in Nacholapithecus is specialized for higher stability than that in proconsulids. The humeroradial joint (humeral capitulum) resembles that of extant apes and Sivapithecus. This condition may represent an intermediate stage leading to the fully modern elbow in extant apes. If this is the case, specialization of the humeroradial joint preceded that of the humeroulnar joint. Nacholapithecus elbow joint morphology suggests more enhanced forearm rotation compared to proconsulids. This observation accords with the forelimb-dominated positional behavior of Nacholapithecus relative to proconsulids, which has been proposed on the grounds of limb proportions and the morphology of the phalanges, shoulder girdle, and vertebrae.
A new excavation of the Iyai rock-shelter site has uncovered more than a dozen human skeletal remains from the Initial Jomon period. We describe here an almost complete female skeleton (Iyai 1), and examine this in the context of morphological variation in Jomon females, especially those of the Initial Jomon period. Two radiocarbon dates based on the Iyai 1 skeletal samples show a calibrated date c. 8300–8200 calBP, belonging to the later part of the Initial Jomon period. The Iyai 1 skeleton was found in a burial pit with an unusual body placement. Although it was a flexed burial with the both arms and limbs flexed, the upper and lower body was disconnected at the waist and the two portions placed on top of each other: the upper body was laid on its abdomen with the head faced into the pelvis, and the lower body was found under the upper trunk in a supine position. The individual is a young female, 146 cm in height using Sasou–Fujii method, and the age at death is estimated as c. 20–40 years. The neurocranium is long (cranial index = 79.9) and high (length–height index = 77.1), the face is wide and low (upper-facial index = 43.4). The dentition shows nearly horizontal heavy wear but no dental caries with an edge-to-edge bite occlusion. The postcranial long bones are gracile, although they exhibit clear musculature impressions in some attachment areas. No paleopathological bone modification was found. The talus exhibits a ‘squatting’ facet at the anterior contact of the talocrural joint. The stable isotopic signature of Iyai 1 falls among those of the inland Initial Jomon people, indicating that her proteins mainly came from C3 plants and terrestrial animals.