The Koboro cave on the northern coast of the Volcano Bay in the southwestern part of Hokkaido Island is prehistoric site yielded several skeletal remains at archaeological investigation in 1952 and 1961. Only one skeleton (No. 4) of them had positive evidence of burial and stratigraphy, whereas other individuals were excavated from disturbed sediments therefore their chronology was unknown. The 2nd investigation in 2006 confirmed that an adult male without skull was buried at rock shelter to the east of the Koboro cave. In this study, we measured radiocarbon (¹⁴C) ages utilized sample from skeletal materials in order to decide their chronology and anthropological placements. However, conventional ¹⁴C ages from skeletal remains on the coast of the Volcano Bay tend to be several hundred years older than correct ages for the marine reservoir effects and regional upwelling of deep water. We evaluated the ratios of terrestrial/marine original carbon referred to stable isotopic analysis, and besides, calibrated the ¹⁴C ages of each material on the basis of the calibration program mixed IntCal09 and Marine09. It is appreciated that this procedure is effective to dating of human skeletons taken in many marine products from comparison with tephrochronology in other neighboring archaeological site, Usu-4 site. Present study indicated that most materials from the Koboro cave were placed in the Epi-Jomon period (ca 400BC–700AD) and morphology of a part of individuals was not contradictory to this finding, but individual No. 2 might date to the Satsumon period (ca 700AD–1400AD). A skeleton from rock shelter was assessed as Ainu after the latter 17th century, considered the calibrated ages, a metallic mouthpiece for smoking, and morphology of limbs, hand bones and mandible.

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This study examined the temporal changes of the bony-birth canal from Jomon to modern Japanese in order to test the hypothesis that the bony birth-canal form of the mother is one of the decision factors of the cranial shape. The outcomes are as follows, Jomon population had the biggest bony-birth canal. In Yayoi and the Medieval populations, the sagittal diameter of the pelvic inlet is relatively short, and the transverse diameter of the pelvic inlet is long. In the early modern, the modern and the present populations, the sagittal diameter of the pelvic inlet is relatively long, and the transverse diameter of the pelvic inlet is short. All measurements of the pelvic outlet continue to decrease from the Jomon period onward. This study also examined correlations between the temporal changes of the pelvic inlet and those of the cranial shape. The temporal changes of the pelvic inlet shape were correlated with the temporal changes of the cranial shape. These results support the hypothesis that the bony birth-canal form of the mother is one of the determining factors of the cranial shape. It was also shown that the size of the bony-birth canal was not correlated with the temporal change of stature. This shows that the size of the bony-birth canal is not associated with the body size.

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Eight adult and four infant human remains dating back to the Earliest Jomon age, excavated in the Tochibara rock-shelter site, Nagano prefecture, Central Japan, exhibited general Jomon features, such as low facial height, pilasteric femur, and marked tooth abrasion. They show specific features of the Earliest and Early Jomon people—an extremely short face and a small mandible with a thin corpus. Although their face was small, masticatory function might have been well-developed. In the male skeletons, the lower limb bones are almost equal in thickness to those of Later and Latest Jomon males, but the upper limb bones are more slender than those of Late and Latest Jomon males. The female upper and lower limb bones are almost equal in thickness to those of Later and Latest Jomon females. Considerable change might have occurred in the way of life of Early to Late Jomon men, for example, from nomadic to stable residence, as well as from pure gathering/hunting to gathering/hunting with primitive agriculture. The skeletons also exhibit various pathological lesions, such as enamel hypoplasia, Harris’s lines, osteoarthritis in the mandibular joint, carious teeth, and radicular cysts, which imply that the daily life of the Earliest Jomon people was difficult. By comparison of the Tochibara skeletons with other Jomon skeletons, the so-called specific features of Earliest and Early Jomon skeletons were re-confirmed, with some modifications: 1) extremely short face, 2) small mandible but wide and forward-projecting coronoid process, 3) slender upper limb bones, and 4) heavy abrasion of mandibular teeth. Recently, it was suggested that the Jomon people were not homogeneous but consisted of various subgroups, according to their mt-DNA haplotype. The specific morphological features of the Earliest and Early Jomon people must be considered from the viewpoints of both phylogenetic differences and change in life-style.

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The Minatogawa Fissure site on Okinawa Island is known from its Late Pleistocene human fossils represented by four partial skeletons. Radiocarbon dates of 18250 ± 650 BP and 16600 ± 300 BP have been reported on associated charcoal, but interpretations of the age of the fossils have been clouded from a paucity of published contextual data. We therefore set out to critically examine all information available to us, with the aim to unambiguously clarify the chronological status of the Minatogawa fossils. Up to 57 information cards accompany the fossil assemblage, with excavation grid, date, and bone part data. The details of this information are highly congruent with several other sources, Seiho Oyama’s personal memoir and excavation charts, Naotune Watanabe’s brief reports, and the inscriptions on the fossil bones themselves. We conclude that the following reliable inferences can be made. Most parts of the Minatogawa II, III, and IV individuals were collected/excavated between August 21 to 23, 1970, during N. Watanabe’s presence at the site, predominantly from grids A2/A3 to C4. The Minatogawa I individual was discovered by S. Oyama, between September and November, 1970, from grids C5/6 to D6 lower in the fissure site. The dated charcoal samples were recovered in the clay layer that contained individuals II, III, and IV and abundant wild boar remains. During our investigation, we also newly identified a few human fossil bones in the 1968/69 Minatogawa Fissure and Yamashita-cho Cave I collections. We present here an updated listing of these and the 1970 Minatogawa human fossil collections.

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