A female human skeleton from the Initial Jomon period found in the Iyai rock shelter in mountainous Kanto, Japan

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 (upperfacial index = 43.4). The dentition shows nearly horizontal heavy wear but no dental caries with an edgeto-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.