As a step toward clarifying the causes of brachycephalization, ecological correlations, i.e. inter-group correlations, between neurocranial and limb bone measurements were investigated using Spearman’s rank correlation coefficient on the basis of 24 male and 23 female samples from prehistoric, historic and modern Japanese populations. It was found that there were significant ecological correlations common to males and females between cranial length and some thickness measurements of the radius, ulna, femur, and tibia, but no consistent correlations between cranial breadth and any limb bone measurements. These findings are compatible with one of the tendencies seen in previous intra-group analyses, and suggest that brachycephalization or dolichocephalization associated with cranial length may have been partly caused by diachronic change in the degree of development of skeletal muscles. This, in turn, may have occurred in accordance with diachronic changes in quality and quantity of available nutrition, physical activity, etc.

抄録全体を表示

This study investigates geographical and temporal variation in three sets of transverse facial flatness measurements—the frontal, simotic, and zygomaxillary indices—in cranial series dating from the Jomon to modern periods of eastern Japan (Hokkaido, Tohoku and Kanto). In Hokkaido, the Ainu retains an early condition of facial features, linking them to the Jomon and Epi-Jomon groups. On the other hand, there were sudden changes from the Jomon to Kofun and from the Edo to modern periods in the Tohoku and Kanto regions. In the Jomon and Hokkaido groups, the similarities in facial morphology probably reflect a similar lifestyle and a close genetic relationship. This contrasts with the changes seen in the Tohoku and Kanto regions, which may result not only from gene flow but also from changes in the pattern of subsistence.

抄録全体を表示

We describe the postcranial bones of a partial skeleton of a male infant Nacholapithecus kerioi (KNM-BG 37800) from the Middle Miocene of Kenya. The skeletal elements are associated with dental remains and its age is presumed to be 6–15 months based on a comparison with an infant Proconsul heseloni with a similar dental growth stage. The postcranial elements include the left scapula, a lumbar vertebra, left distal humerus, right proximal ulna, right radius, right and left proximal femora, a proximal fragment of metatarsal, and proximal and intermediate phalanges. Its body mass was estimated as 3.0 kg from shaft dimensions of the humerus and femur. At this early postnatal developmental stage, N. kerioi can be distinguished from P. heseloni in several postcranial features: a caudally projecting lumbar spinous process, strong dorsal divergence of the scapular spine, a coronoid fossa which is more developed than the radial fossa, higher neck shaft angle of the femur, taller trochlea of phalanges, and a lower brachial index. These features, except for the last, agree with the previously proposed positional behavioral reconstruction of N. kerioi, in which vertical climbing, orthograde clambering, transferring, or bridging are relatively important compared with P. heseloni. The apparently low brachial index results from a comparatively short radius for the predicted body mass. This might imply a relatively slow pace of growth in the radius of N. kerioi. However, it might result from body mass overestimation, incorrect length reconstruction, or individual variation. Its interpretation must await further specimens.

抄録全体を表示

The Woranso-Mille paleontological study area is located in the central Afar region of Ethiopia, about 360 km northeast of the capital, Addis Ababa. Some parts of this area have been paleontologically known since the 1970s. However, most of the fossiliferous areas were discovered by surveys conducted in the region between 2002 and 2004. By the end of the 2006 field season, a total of 17 vertebrate localities had been designated, and more than 1000 vertebrate fossil specimens collected. Among these specimens, there are more than 20 fossil hominid craniodental and postcranial remains, including one partial skeleton, of Pliocene age (3.5–3.8 Ma). Research at this study area has thus far focused on the geology and paleontology of the early Pliocene deposits along the Mille river and adjacent areas located between the towns of Mille and Chifra. Exposed sediments in the new fossiliferous area are mostly silty sand and silty clay horizons interbedded with a number of volcanic tuffs and basaltic flows suitable for ⁴⁰Ar/³⁹Ar radioisotopic dating. The total stratigraphic section is about 50 m thick with a minimum age of ~3.5 Ma. The study area also has deposits of early to middle Pleistocene age, although no locality has been designated to date. The new Woranso-Mille paleontological study area provides a crucial temporal window into the time during which Australopithecus anamensis (3.9–4.2 Ma) appears to have given rise to Australopithecus afarensis (3.0–3.6 Ma). Radiometric dates have thus far yielded a minimum age of 3.5 Ma for the hominid localities and this conforms well with a biochronological age estimate of 3.6–3.8 Ma. The associated fauna, particularly the abundance of fossil cercopithecids and presence of diverse aquatic fossil vertebrates, indicates a relatively closed, wooded habitat probably associated with a paleo-Mille river.

抄録全体を表示

Tanged points have long been considered an important proxy for cultural variability during the Incipient Jomon period of Japan. Historically, interpretations of cultural variability based on tanged points have relied entirely on studies of tang morphology. However, little attention has been paid to technological variation, which is a stronger indicator of culturally learned behavior than are morphological typologies. This paper describes ongoing research of flake scar orientation on tanged points produced by the oblique parallel pressure flaking (OPPF) technique from the Incipient Jomon. The results indicate that there is a highly significant, geographically patterned technological variation of such points. OPPF points from the south of Japan are exclusively flaked from the upper right to the lower left (URLL), while points from the north are almost always flaked from the upper left to the lower right (ULLR). Experimental research by the author and others suggests that this variation may indicate the adoption of different pressure flaking techniques in these two regions. If one considers the diversity of the flake scar patterns as an indicator of isochrestic variation in the Incipient Jomon period, the people of both regions appear to have had different culturally conditioned techniques of pressure flaking. This suggests that they did not adopt the same traditional rules concerning pressure flaking, nor did they have identical cultural behavior.

抄録全体を表示

We had the opportunity to examine a pre-Columbian Peruvian child (about 4–5 years old) cranium with a healed lesion above the inion on the occiput. It has previously been claimed that supra-inion lesions represent traces of prehistoric trepanation for ritual or prophylactic reasons in childhood, a practice termed ‘trepanation supra-iniana’. An alternative hypothesis claimed that such lesions mainly result from abnormal long-term compression caused by artificial deformation. We describe several macroscopic characteristics of the cranium and discuss the claim that it is a case of ‘trepanation supra-iniana’. The cranium is also characterized by an artificial anterior–posterior deformation, unilateral stenosis of the external auditory canal on the right side, and small drill holes on this same side in the frontal region. The supra-inion lesion, consisting of a shallow depression and a fissure-like orifice, is located slightly to the right on the occiput. The morphological-pathological state of the lesion is analogous to the healing of a trepanation by scraping. These observations suggest that the lesion did not result from artificial compression by head deformation, but from the infliction of trepanation identical to ‘trepanation supra-iniana’. The observed stenosis of the external auditory canal is clearly congenital. It is considered that this clearly visible auditory deformity was the primary reason for conducting the ritual or prophylactic trepanation. The small drill holes in the frontal region may have been a post-mortem or peri-mortem trepanation of a ritual or superstitious nature.

抄録全体を表示