Showing papers in "Anthropological Science in 2007"

Early Pleistocene Homo erectus fossils from Konso, southern Ethiopia

Abstract: Homo erectus has been broadly defined to include fossils from Africa, Asia, and possibly Europe, or restricted to a supposedly confined Asian clade. Recently discovered fossils of H. erectus are allowing new insights into aspects of its evolution, such as the timing and mode of the species' emergence in Africa and its relationship to Asian populations. However, the currently available African record predating 1.0 Ma is poor, consisting of the Turkana basin, Olduvai and the more limited South African materials. Here, we describe and compare eight craniodental fossils of ~1.4 Ma recovered from Konso, Ethiopia, that we attribute to H. erectus. These include KGA10-1, one of the better-preserved H. erectus mandibular specimens known from eastern Africa, and other fragmentary dental and cranial remains. The Konso H. erectus fossils show a mosaic of primitive and derived features. These include a large and thick mandibular corpus, a moderately developed lateral prominence, a reduced premolar morphology, and a tendency for smaller relative sizes of the posterior molars compared with earlier Homo. In some dentognathic details, such as the lack of a buccolingually narrow M1 and the presence of double mental foramina, the Konso fossils differ from eastern African H. erectus of ≥1.5 Ma. The fragmentary cranial remains exhibit weak angular and occipital tori, and an apparently weak occipital flexion, as with the eastern African H. erectus examples known from ~1.65 to 1.2 Ma. The available evidence is consistent with the interpretation that African early H. erectus shows morphological con- tinuity within the ~1.65 to 1.0 Ma time period, with relatively little morphological evolution prior to 1.4 Ma and advanced dentognathic gracility occurring sometime thereafter. The Konso evidence cor- roborates the hypothesis that the African H. erectus populations represent a variable but continuous evolutionary succession that was a likely source of multiple events of gene flow to the Eurasian con- tinent.

A new great ape from the late Miocene of Turkey

Abstract: An adult maxilla and partial mandibles of a hominoid primate recovered from the late Miocene locality of Corakyerler (central Anatolia) are recognized as a new species of Ouranopithecus, one of the rare western Eurasian hominoids to have survived well into the late Miocene. This species is distinguished from its sister taxon, and likely ancestor Ouranopithecus macedoniensis, by a constellation of dentognathic features. The new species, in which the male postcanine dentition is larger than that of any other Miocene ape besides Gigantopithecus, is associated with evidence indicating an open, dry environment. Dental features of Ouranopithecus apparently evolved in parallel with later Australopithecus, and suggest that Ouranopithecus was adapted to a diet of tough/abrasive foods.

Somatotypes of young male athletes and non-athlete students in Yogyakarta, Indonesia

Abstract: There is a considerable corpus of evidence indicating that athletes succeeding in certain sports have distinctive body shapes that differ according to the demands of the type of sports and competitive level The aim of this study was to determine the specific morphological characteristics of young male athletes compared with non-athlete students in Indonesia Anthropometric measurements of 19 badminton players, 96 soccer players, 74 volleyball players, and 51 non-athlete undergraduate students, aged 16 to 28, were obtained in 1994 and 1995 Stature, body weight, bicondylar breadths of the humerus and femur, calf and upper arm circumferences, and skinfolds (at triceps, subscapula, calf, and supraspine) were measured for each subject Heath-Carter somatotypes were determined in all the subjects The results of the ANOVA of the body measurements showed that the three groups of athletes and the non-athlete students were heterogeneous: the badminton players were shorter and lighter with greater skinfold values among the athlete groups; the soccer players were relatively shorter and with smaller skinfold values and greater arm and leg girths; and the volleyball players were taller and heavier with smaller elbow and knee breadths and very small skinfold values The non-athlete students were characterized by greater arm girth, elbow breadths, knee breadths, and back and leg skinfolds In mean somatotype category, the badminton players were ‘central’ (33-37-37), the soccer players were ‘balanced mesomorph’ (27-49-30), the volleyball players were ‘mesomorph-ectomorph’ (24-35-37), and the non-athlete students were ‘ectomorphic mesomorph’ (27-52-38) Comparisons of international scope with each of the different sports showed that the Indonesian players were extremely short and light

Effects of aging on gait patterns in the healthy elderly

Abstract: The free gait of 52 healthy elderly persons was examined. All the subjects were volunteers, aged 65 years or older, and lived in the community in the Kaga area, Ishikawa Prefecture, Japan. They were healthy and active enough to attend the study location by themselves. The comparison group of young adults consisted of 20 volunteer students. The percentages of females and males were similar in the two groups. The healthy elderly walked more slowly than the young adults. Their slower speed was largely caused by their shorter stride length. Differences were still observed between the young and elderly groups when gait parameters were presented in the form of dimensionless numbers. The elderly were weaker in grip strength and had shorter single-leg balance with eyes open than the young adults. The number of steps per day correlated negatively with age within the elderly group. Negative correlations between age and walking speed, as measured directly or in terms of dimensionless numbers, and between age and stride length were also observed within the elderly group. The relative stance phase duration correlated positively with age within the elderly group. Slow speed may be related to low daily activity, reduced muscle power, and diminished balance ability. Long stance phase duration and slow speed in the elderly could be an adaptive characteristic in response to impaired balance.

Preliminary geology and paleontology of new hominid-bearing Pliocene localities in the central Afar region of Ethiopia

Abstract: 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.

Non-metric dental trait variation among local sites and regional groups of the Neolithic Jomon period, Japan

Abstract: Inter-populational heterogeneity of the Neolithic Jomon hunter-gatherers of Japan was examined via 21 non-metric dental traits. Skeletal samples from nine local sites and five regional groups of the middle to final stages of the Jomon period were analyzed, and inter-site comparisons were made among five representative sites (Ubayama, Nakazuma, Ikawazu, Yoshiko, and Tsukumo). Statistically significant differences were found in 4/21 traits in the inter-site comparisons, and in 5/21 traits in the inter-regional comparisons between the Hokkaido, Tohoku, Kanto, Tokai, and Sanyo groups. Smith’s distances suggest that the inter-regional differences within the Jomon assemblages are minor when compared with differences from the non-Jomon samples such as the Yayoi immigrants, Kofun, and modern Japanese. Furthermore, examination of the wider geographical variation of the Jomon people (eastern versus western) revealed significant differences in only 2/21 traits. Distance analysis showed that the eastern and western Jomon groups clustered together, and exhibited the greatest affinities with present-day Southeast Asians among comparable East Asian and Pacific population samples. The Jomon people can be collectively regarded as relatively homogeneous, within the broader context of East Asian and Pacific intra-population variation.

Non-metric dental variation of Sakishima Islanders, Okinawa, Japan: a comparative study among Sakishima and neighboring populations

Abstract: Twenty-four non-metric tooth crown traits of Miyako and Ishigaki Islanders, from the southernmost Ryukyu Islands, were investigated and compared with those of neighboring populations. The frequency of double-shoveling in Sakishima samples, and especially, Ishigaki Island, is lower than that found among Atayal people (Taiwan) and main-island Japanese. The frequencies of protostylid and cusp 6 in Miyako and Ishigaki Islanders are comparable to those in Hokkaido Ainu and lower than in main-island Japanese and Atayal. Miyako and Ishigaki Islanders, as well as other Ryukyuans, are basically more similar to main-island Japanese than to Ainu, while being situated between main-island Japanese and Ainu in terms of both mean measure of divergence (MMD) and R-matrix methods. However, Ishigaki and Miyako Islanders are relatively close to Hokkaido Ainu among Ryukyu people and main-island Japanese, as suggested in some previous preliminary studies. The estimated Fst (the ratio of among-group variation to total variation), using an average heritability rate = 0.55 for the non-metric tooth crown traits used in this study, displayed low levels of inter-regional variation, as already indicated in analyses of genetic, cranial and dental metric data. Meanwhile, the relatively large diversity of Ryukyu Islanders based on Fst suggested long-term isolation or poor intra-island contact among the Ryukyu Islands. The lower observed variation compared with the expected variation in most Ryukyu samples may reflect a greater degree of genetic drift in the Ryukyu Island chain.

Functional significance of bone distribution in the human mandibular symphysis

Abstract: Investigations of nonhuman primate mandibles have demonstrated that they are bent, twisted, and sheared during the power stroke of mastication. Inferences have been made regarding potential relationships between local stress patterns and the external morphology of the mandibular symphysis. This study reports the quantitative assessment of cross-sectional bone distribution patterns in the modern human symphysis by use of high-resolution microfocal X-ray computed tomography. Parameters that were examined include (1) bone substance area, (2) the ratio of bone substance to total cross-sectional area, and (3) cortical thicknesses along the perimeters of the symphyseal cross-section. The observed bone distribution was then compared with the hypothetical patterns of mechanical stress during mastication. Results showed that cortical bone was significantly thicker on the lingual than on the labial aspect of the symphysis at all superoinferior levels. The thickest cortical bone was observed on the lingual aspect of the symphysis immediately inferior to the mental spine, and labially at the mental protuberance. Bone area measurements were largest and second largest in the inferolingual and inferolabial quadrants of the symphyseal cross-section. These results show that bone is concentrated particularly at the lower lingual aspect of the symphysis, which is thought to experience high concentrations of tensile stress during mastication. Such a bone distribution pattern contributes to decreasing stress gradients in the mandibular symphysis, and therefore provides some support to the idea that bone distribution of the mandibular symphysis is in part determined by function.

Metric dental diversity of Ryukyu Islanders: a comparative study among Ryukyu and other Asian populations

Abstract: Mesiodistal and buccolingual crown diameters were examined to describe and compare patterns of metric dental variation in five modern samples from the Ryukyu Island chain (Miyako, Ishigaki, Tokunoshima, and two samples from Okinawa Island). Principal component analysis applied to two separate datasets, raw measurement and standardized (C-score) data, for 32 Asian and Pacific samples, including the five Ryukyu Islander series, produced an overall size factor and three shape factors (relative size of mesiodistal diameters versus buccolingual diameters and two kinds of front-back polarity). Ryukyu Islanders have similar crown dimensions as those of the predominant eastern Asian groups, characterized by mesodont dentition. In terms of shape factors, Ryukyu Islanders are distinctive among eastern Asian population groups on the one hand, and show diversity among themselves on the other hand. The inter-regional variation of Ryukyu Island groups estimated by Fst falls within the range of 4–6% of the total variance, which is greater than those of Arctic population samples (Aleuts and Eskimos). The average within-group variance of the Ryukyu Island series measured by the R-matrix method (intra-regional variation) is compatible with those of East and Northeast Asians, Micronesians, and Polynesians. These findings suggest that differential patterns of long-term gene flow from an outside source, geographical isolation, and genetic drift in each island of the Ryukyu Island chain has produced the morphological diversification of modern Ryukyu Islanders.

Distinguishing archeological and paleontological faunal collections from Pleistocene Japan: taphonomic perspectives from Hanaizumi

Abstract: The application of modern methodological taphonomic approaches to Pleistocene faunal assemblages that were excavated and interpreted before taphonomic analyses became common are crit- ical to verifying whether the original interpretations are valid. Even though taphonomic research is common in North America, Africa, and Europe, few such studies of faunal collections have been car- ried out in East Asia. In this regard, taphonomic analysis of the faunal assemblage from Hanaizumi, Japan serves as an excellent case study because few taphonomic re-analyses of previously excavated Pleistocene assemblages have been performed in Japan. Hanaizumi was excavated in the 1950s and the original behavioral interpretation was that hunter-gatherers were responsible for the accumulation of the faunal assemblage, which is dominated by bison (Bison priscus). The taphonomic analysis pre- sented here indicates that evidence of human modification is present on the bones. However, results suggest that even though hunter-gatherers may have had primary access to many of the bison in the assemblage, Hanaizumi was probably not a kill site or a hunter-gatherer home base as was originally proposed. Rather, the acquisition of bison may have taken place further up river and Hanaizumi is the locality to which the already processed carcasses were transported via fluvial movement. Accordingly, it is difficult to use the Hanaizumi faunal dataset to address current paleoanthropological debates. Future fieldwork at the site may indicate that hunter-gatherers played a more significant role in the for- mation of the bison bone assemblage. For now, Hanaizumi is best considered an allochthonous pale- ontological collection that has assisted in paleoenvironmental reconstructions of Late Pleistocene Japan.

Distal humerus and ulna of Parapresbytis (Colobinae) from the Pliocene of Russia and Mongolia: phylogenetic and ecological implications based on elbow morphology

Abstract: Parapresbytis eohanuman is a colobine known from two middle Pliocene localities south- east of Lake Baikal, northern East Asia. This study examined the morphology of postcranial speci- mens, a distal humerus and an ulna, of Parapresbytis. A total of 18 and 13 linear measurements were taken from the humerus and the ulna, respectively, and compared with those of extant and European fossil colobines using principal components analysis. The distal humeral specimen of Parapresbytis is slightly larger than those of male Semnopithecus and Nasalis, while the ulnar specimen is much larger than those of extant colobines and is nearly as large as that of a male Papio ursinus. Morphologically, the distal humeri and ulnae of terrestrial colobines such as Semnopithecus, Dolichopithecus, and Meso- pithecus can be distinguished from those of arboreal colobines. The morphology of the Parapresbytis elbow is within the range of the arboreal colobines, contradicting previous suggestions that this genus is terrestrially adapted and is phylogenetically close to Dolichopithecus. Because the arboreally adapted elbow is shared by most extant colobines, the morphology of the elbow does not provide evi- dence for phylogenetic proximity between Parapresbytis and a particular taxon of arboreal colobine such as Rhinopithecus. The elbow morphology suggests that Parapresbytis was adapted to arboreal locomotion as much as the extant arboreal colobines are. This is congruent with the paleoenvironmen- tal evidence, which indicates the presence of forests in the Lake Baikal area during the middle Pliocene.

Flake scar patterns of Japanese tanged points: toward an understanding of technological variability during the Incipient Jomon

Abstract: 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.

Geographical and temporal variation in facial flatness in the crania of eastern Japan

Abstract: 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.

Glenohumeral joint surface characters and its relation to forelimb suspensory behavior in three ateline primates, Ateles, Lagothrix, and Alouatta

Abstract: Intergeneric morphological variation of the glenohumeral joint surface was investigated among three ateline genera (Ateles, Lagothrix, Alouatta) and compared with Cebus (an ancestral morphotype of atelines) and Hylobates (a specialized brachiator) to reveal characters associated with forelimb suspensory behavior. Seventy-six skeletal specimens were examined, and articular surface curvature was measured by a three-dimensional digitizer. It was found that Ateles exhibits joint features distinct from the other atelines, but resembles Hylobates in its large breadth–length ratio of the glenoid surface and the humeral head, a relatively spherical humeral head, and a dorsoventrally extensive humeral head relative to the glenoid surface. These morphologies are likely to be related to brachiation, rather than to climbing behavior. A dorsoventrally extensive glenohumeral joint is interpreted to facilitate an increased stride length during brachiation. Lagothrix was found to show many primitive features that are shared with Alouatta in spite of its forelimb suspensory behavior. This may be related to the less specialized mode of forelimb suspensory behavior in Lagothrix compared with Ateles. Those characters that apparently correspond to dependency on suspensory behavior can be useful in interpreting the positional behavior of extinct primate taxa.

Postcranial bones of infant Nacholapithecus: ontogeny and positional behavioral adaptation

Abstract: 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.

Social relationships of male Japanese macaques (Macaca fuscata) in different habitats: a comparison between Yakushima island and Shimokita peninsula populations

Abstract: Wild troops of the Japanese macaque (Macaca fuscata) live in various habitats within the Japanese archipelago. The social relationships of males can be elucidated through intraspecific comparisons of social conditions between populations of different habitats. Previous research has shown that males associate with one another more frequently on Yakushima island than on Kinkazan island, whereas male–female and female–female relationships did not differ between populations that occupy the two different habitats. However, this study did not compare the social relationships of males between habitats during the mating season, when males are expected to compete for fertile females more aggressively within and between troops. The present study compared male behavior in Yakushima island and the Shimokita peninsula populations during the mating season and found that males exchanged affiliative behaviors with one another more frequently on Yakushima island. The socionomic sex ratio (SSR: adult males/adult females) was higher in the Yakushima island troop, and this troop was involved in inter-troop encounters more frequently. In Yakushima island, more non-troop males were observed around the troop and were frequently involved in agonistic interactions with troop males. Yakushima island troop males are likely to affiliate with one another to reduce tension among themselves, in order to cooperatively attack neighboring troops and non-troop males that appear to copulate with fertile females.

Low AMTL ratios in medieval Japanese dentition excavated from the Yuigahama-minami site in Kamakura

Abstract: Ante-mortem tooth loss (AMTL) in a medieval Japanese ‘Yuigahama-minami’ population excavated at Kamakura, Kanagawa prefecture, was examined. In the medieval period, Minamoto Yoritomo established the shogunate in Kamakura, and many battles were fought around Kamakura. Human skeletons from the medieval sites in Kamakura are considered to be casualties of these battles. The AMTL ratio in Kamakura medieval skeletons, as reported in previous work, is very low. If these medieval skeletons derive from death in battle, they can be expected to be comparatively younger than those deriving from natural death; and if the ratio of younger skeletons is high, the AMTL ratio would naturally be expected to be comparatively low. The findings of the present study indicate that AMTL ratios in this medieval population, not only in the young, but also in the elderly, were low for the period. A comparison of AMTL ratios in the Yuigahama-minami with the Miwanoyama medieval population in Chiba prefecture indicates that the low AMTL ratio in the former was not a common characteristic of the medieval Japanese, and that there were regional differences in AMTL ratios in the period. Comparisons also show that the ratios of dental caries in both the young and elderly Yuigahama-minami medieval population were lower than among other early Japanese. Not only the AMTL, but also the dental caries ratios of Yuigahama-minami males were significantly lower than those of Yuigahama-minami females, both young and elderly. It therefore appears that Yuigahama-minami males had exceptionally good dental health.

A Possible case of prophylactic supra-inion trepanation in a child cranium with an auditory deformity (pre-Columbian Ancon site, Peru)

Abstract: 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.

Ecological correlations between neurocranial and limb bone measurements: toward the solution of the brachycephalization problem

Abstract: 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.

Effects of erect bipedal standing on the morphology of rat vertebral bodies

Abstract: An osteometric approach was used to demonstrate the relationship between vertebral body morphology and bipedal standing using 17 rats, which had been divided into control and exercise groups Only the latter group (n = 9) performed a series of bipedal standing exercises using operant conditioning Statistical analysis was conducted to allow for inter-group comparisons with respect to six linear dimensions and five indices for each of the 24 vertebral bodies, from the third cervical through the last lumbar vertebrae Detected effects of bipedal standing exercises on the vertebral body were as follows: (1) dorsal height decreased from the caudal thoracic to the lumbar vertebrae; (2) the dorsoventral diameter of the cranial surface increased at the thoracolumbar level; (3) the dorsal-to-ventral height ratio decreased in the lumbar vertebrae; (4) the dorsoventral-to-transverse diameter ratio of the cranial surface increased in the middle thoracic and lumbar vertebrae; and (5) the height-to-dorsoventral diameter ratio decreased in the fifth thoracic vertebra, and from the tenth thoracic to the fourth lumbar vertebrae In vertebral bodies at the thoracic and lumbar levels, experimentally induced osteological changes such as wedging, dorsoventral elongation, and craniocaudal robusticity were discussed in terms of their comparative morphology in humans and quadrupedal mammals, and then compared with those of a bipedally trained Japanese macaque

The cranium and mandible of Minatogawa 1 belong to the same individual: a response to recent claims to the contrary

Abstract: Minatogawa 1 is one of the rare well-preserved remains of Late Paleolithic Homo sapiens from East Asia, and is central to the investigation on the earlier phase of peopling in this region. In order to test the recent claim that the cranium and mandible of this specimen belong to different individuals, I re-examined its occlusion allowing for minor but significant distortion present in the original fossil specimen. It was confirmed that, when a correction is made for such a distortion, the maxillary and mandibular dentitions occlude perfectly in a normal Class I relation. Thus, the cranium and mandible of Minatogawa 1 no doubt belong to the same individual. A revised description on the state of tooth wear in Minatogawa 1 is also presented. No clear evidence of habitual non-masticatory oral activities is recognized, and the severe occlusal wear in this individual seems to result primarily from the nature of their foods and/or the food preparation techniques they used.