論文

The highly fragmented and distorted skull of the adult skeleton ARA-VP-6/500 includes most of the dentition and preserves substantial parts of the face, vault, and base. Anatomical comparisons and micro-computed tomography-based analysis of this and other remains reveal prs-Australopithecus hominid craniofacial morphology and structure. The Ardipithecus ramidus skull exhibits a small endocranial capacity (300 to 350 cubic centimeters), small cranial size relative to body size, considerable midfacial projection, and a lack of modern African ape-like extreme lower facial prognathism. Its short posterior cranial base differs from that of both Pan troglodytes and P. paniscus. Ar. ramidus lacks the broad, anteriorly situated zygomaxillary facial skeleton developed in later Australopithecus. This combination of features is apparently shared by Sahelanthropus, showing that the Mio-Pliocene hominid cranium differed substantially from those of both extant apes and Australopithecus.

© 2014 Macmillan Publishers Limited. All rights reserved. Recent studies of an increasing number of hominin fossils highlight regional and chronological diversities of archaic Homo in the Pleistocene of eastern Asia. However, such a realization is still based on limited geographical occurrences mainly from Indonesia, China and Russian Altai. Here we describe a newly discovered archaic Homo mandible from Taiwan (Penghu 1), which further increases the diversity of Pleistocene Asian hominins. Penghu 1 revealed an unexpectedly late survival (younger than 450 but most likely 190-10 thousand years ago) of robust, apparently primitive dentognathic morphology in the periphery of the continent, which is unknown among the penecontemporaneous fossil records from other regions of Asia except for the mid-Middle Pleistocene Homo from Hexian, Eastern China. Such patterns of geographic trait distribution cannot be simply explained by clinal geographic variation of Homo erectus between northern China and Java, and suggests survival of multiple evolutionary lineages among archaic hominins before the arrival of modern humans in the region.

© 2015 Kaifu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Homo floresiensis is an extinct, diminutive hominin species discovered in the Late Pleistocene deposits of Liang Bua cave, Flores, eastern Indonesia. The nature and evolutionary origins of H. floresiensis' unique physical characters have been intensively debated. Based on extensive comparisons using linear metric analyses, crown contour analyses, and other trait-by-trait morphological comparisons, we report here that the dental remains from multiple individuals indicate that H. floresiensis had primitive canine-premolar and advanced molar morphologies, a combination of dental traits unknown in any other hominin species. The primitive aspects are comparable to H. erectus from the Early Pleistocene, whereas some of the molar morphologies are more progressive even compared to those of modern humans. This evidence contradicts the earlier claim of an entirely modern human-like dental morphology of H. floresiensis, while at the same time does not support the hypothesis that H. floresiensis originated from a much older H. habilis or Australopithecus-like small-brained hominin species currently unknown in the Asian fossil record. These results are however consistent with the alternative hypothesis that H. floresiensis derived from an earlier Asian Homo erectus population and experienced substantial body and brain size dwarfism in an isolated insular setting. The dentition of H. floresiensis is not a simple, scaled-down version of earlier hominins.

© 2014 Elsevier Ltd and INQUA. In order to investigate molar enamel thickness and distribution in Gigantopithecus blacki, two maxillary and three mandibular molars were micro-CT scanned, and the 3-dimensional (3D) shape of the enamel crown cap was digitally reconstructed. Results show that G.blacki molars have very thick enamel, over 6mm in places. 3D average thickness of the entire crown relative to crown size was shown to be comparable to that of modern Homo sapiens, and thinner than in the very thick enameled robust Australopithecus condition. Durability of the tooth, calculated as the enamel volume relative to maximum horizontal area of the crown, was shown to be comparable to that of fossil hominids, including Australopithecus robustus. The thick occlusal enamel of G.blacki molars was found to be accompanied by a buccolingual gradient in which thicker enamel occurs on the cusps of the "functional" side. This is associated with higher crown height on the "functional" side of the crown, and implies an adaptation to differential buccolingual wear. These results indicate that G.blacki molars were adapted to heavy wear, but probably in a manner that was different from Pliocene and Pleistocene hominids.

© 2016, © 2015 Taylor & Francis. Dentognathic remains of Gigantopithecus blacki from the newly discovered Early Pleistocene locality of Yanliang Cave, Guangxi, South China are described. These include an incomplete mandible, only the fourth discovered and the first known from a site other than Liucheng, as well as 25 isolated teeth. Comparisons of the Yanliang mandible show that the best preserved part of the right corpus is morphologically similar to the left side of the Liucheng Mandible III. In addition, the Yanliang mandible and the Liucheng Mandible III share a similar degree and pattern of wear on the premolars and molars. The partially resorbed alveolus for the right M2 in the Yanliang mandible indicates antemortem tooth loss, which is the first record of its kind for Gigantopithecus blacki. Comparisons of the enamel–dentine junction morphology show that the isolated upper premolars from Yanliang are similar to those of Gigantopithecus blacki from Early Pleistocene sites, and differ from the more specialised form from the Middle Pleistocene Hejiang Cave. This supports the biochronological evidence that Yanliang Cave is Early Pleistocene in age.

© 2017 Wiley Periodicals, Inc. Objectives: This study presents the first detailed morphological description and comparison of a Middle Pleistocene hominin mandibular fragment (PA 831) and associated teeth from the Hexian site in Eastern China. We aim to investigate where the Hexian mandible fits within the genus Homo variability in the light of an increased and better characterized Asian fossils record. Methods: Comparative samples include Pleistocene Homo mandibles and teeth from Africa, Asia, and Europe, as well as earlier African hominins (Australopithecus and early Homo) and Holocene recent humans. Both conventional morphological description and metric analysis were used. In addition, virtual reconstructions of the enamel dentine junction (EDJ) surface, pulp cavity, and roots with micro-CT were used to the mandible and teeth. Results: The Hexian mandible is characterized by a plesiomorphic structural pattern for the Homo clade, with strong corpus robustness and a subparallel and low-positioned mylohyoid line that differentiates the swollen subalveolar planum from the shallow subalveolar fossa. Features that are derived compared to early Homo include a moderately curved dental arcade, a well-developed lateral prominence placed at the M2-M3 level, and multiple mental foramina. The Hexian mandible's complex enamel surface and strong, stout root structure are primitive traits for the Homo clade. Finally, the highly crenulated “dendrite-like” EDJ found in the molars may represent a dental feature specific to the continental Asian Homo erectus, but more data is needed to confirm this. Conclusions: Mandibular and dental features indicate that the Hexian mandible and teeth differ from northern Chinese H. erectus and European Middle Pleistocene hominins, but show some affinities with the Early Pleistocene specimens from Africa (Homo ergaster) and Java (H. erectus), as well as the Middle-Late Pleistocene mandible from Penghu, Taiwan. Compared to contemporaneous continental Asian hominin populations, the Hexian fossils may represent the survival of a primitive hominin, with more primitive morphologies than other contemporaneous or some chronologically older Asian hominin specimens.

Enamel thickness was investigated in the mesial cusp section of 167 unworn human molars by means of non-destructive micro-CT based methodology. Serial sections of the entire crown were taken at a voxel resolution of 28 microns, and the initial volume data set of each molar was standardized in orientation to obtain a vertical section that accurately contains the dentine tips of the two mesial cusps. Enamel thickness at the cusp tips, occlusal basin, and lateral crown face was measured in the mesial cusp section and in sections offset from that section by 0.6 mm. We found that thickness at the cusp tips may be overestimated in offset sections by up to about 1 mm, and those of the occlusal basin overestimated or underestimated by up to about 0.5 mm. We also found that maximum 'radial' thickness of the lateral crown face was least affected by section position, usually with discrepancies of less than about 0.1-0.2 mm. In all serial positions in both upper and lower molars, a 'functional' (lingual in uppers and buccal in lowers) to 'non-functional' side gradient in enamel thickness was observed in cusp tip, occlusal basin, and lateral crown face enamel, with the exception of the characteristically thin enamel at the protoconid and paracone cusp tips. Serial differences in thickness were seen between the thinner M1 and the two posterior molars in many but not all measures of thickness, the pattern of which appears to be influenced by the thin M1 mesiobuccal cusp enamel. Individual variation of maximum lateral thickness, the least variable measure of thickness, was found to be substantial (a 30-60% range) even with serial and buccolingual positions controlled. Correlation between whole crown average enamel thickness and maximum lateral thickness was high, indicating that the latter is a potentially useful predictor of overall enamel thickness of the molar crown. The present results indicate that interspecific comparisons of enamel thickness must be made with careful attention to positional placement of thickness measures, potential serial differences, and intraspecific variation. © 2005 The Anthropological Society of Nippon.

The Late Pleistocene fossil human remains (individuals I-IV) of Minatogawa, Okinawa Island are important in addressing the population history of the Japanese archipelago and in understanding evolution of Homo sapiens in eastern Asia. This study is the first on Minatogawa I's endocranial morphology, based on micro-computed tomography (micro-CT). We digitally reconstructed the Minatogawa I endocast, and created its physical model using a three-dimensional printer system. We compared the Minatogawa I endocast with available H. sapiens and archaic Homo endocasts. We found that Minatogawa I exhibits key derived endocranial features of H. sapiens, such as a highly elevated parietal, endocranial widening confined to a relatively anterior position, and a narrow internal occipital crest. The short, wide, and low proportioned Minatogawa I endocranium lies metrically at the margins of the modern human ranges of variation of this study. The Minatogawa I endocast exhibits a slightly underdeveloped frontal region with marked parasagittal ridges, a weak endocranial parietal boss, and a strong temporal bulge. It differs from Liujiang in the strong expression of these features as well as in overall metric proportions. A weak endocranial parietal boss and a strong temporal bulge are shared by Skhul V and Qafzeh 9, and may represent a primitive condition for H. sapiens in general. © 2010 The Anthropological Society of Nippon.

In order to describe molar enamel thickness more accurately, a new measurement method using a laser triangulation system has been developed and its repeating accuracy was tested. The method was then applied to investigate the changing pattern of lateral enamel thickness along the distal protoconid crest. The results indicated that lateral enamel thickness at different sections tends to be comparable in relation to distance from the dentine tip. We expect this method to become an effective tool to investigate not only thickness of enamel but also its three-dimensional morphology.

With the discovery of Ardipithecus, Orrorin and Sahelanthropus, our knowledge of hominid evolution before the emergence of Pliocene species of Australopithecus has significantly increased, extending the hominid fossil record back to at least 6 million years (Myr) ago. However, because of the dearth of fossil hominoid remains in sub-Saharan Africa spanning the period 12-7 Myr ago, nothing is known of the actual timing and mode of divergence of the African ape and hominid lineages. Most genomic-based studies suggest a late divergence date - 5-6 Myr ago and 6-8 Myr ago for the human-chimp and human-gorilla splits, respectively - and some palaeontological and molecular analyses hypothesize a Eurasian origin of the African ape and hominid clade. We report here the discovery and recognition of a new species of great ape, Chororapithecus abyssinicus, from the 10-10.5-Myr-old deposits of the Chorora Formation at the southern margin of the Afar rift. To the best of our knowledge, these are the first fossils of a large-bodied Miocene ape from the African continent north of Kenya. They exhibit a gorilla-sized dentition that combines distinct shearing crests with thick enamel on its 'functional' side cusps. Visualization of the enamel-dentine junction by micro-computed tomography reveals shearing crest features that partly resemble the modern gorilla condition. These features represent genetically based structural modifications probably associated with an initial adaptation to a comparatively fibrous diet. The relatively flat cuspal enamel-dentine junction and thick enamel, however, suggest a concurrent adaptation to hard and/or abrasive food items. The combined evidence suggests that Chororapithecus may be a basal member of the gorilla clade, and that the latter exhibited some amount of adaptive and phyletic diversity at around 10-11 Myr ago. ©2007 Nature Publishing Group.

In measuring basal crown and cusp areas of molars, one must determine a standard reference plane on which the projected measurements are made. In this paper, we present a new three-dimensionally based system which enables an objective determination of crown orientation. This is done by combining five laser scanned images of a molar taken occlusally and from four oblique angles to form a composite three-dimensional representation of the entire molar crown surface. Using this digitized data set, we derive a standard occlusal orientation that maximizes projected occlusal surface area. We can also choose other orientations for projection, such as those defined by the cervical line or cusp apices. Crown and cusp areas were measured in each of these orientations and compared for discrepancies on a mandibular first molar of Australopithecus afarensis. We found that orientations differ by more than 10 degrees, resulting in large discrepancies in cusp area values. It is concluded that, to enable reliable interpretation of cusp area data, whatever orientation methods used should be carefully chosen and rigidly followed.

The morphology of the enamel cap and the thickness of the enamel of human molars are regarded as closely related to function. Previously, enamel thickness has been studied in specific sections only, not the distribution patterns of the entire crown. Here, the three-dimensional distribution pattern of the enamel of human permanent first molars was examined with a newly developed system. A distinctive pattern of enamel thickness common to all the individuals examined was found, regardless of the variation in absolute enamel thickness among individuals. It was confirmed that the lingual faces of upper molars and the buccal faces of lower molars have thicker enamel than the other crown faces. Moreover, in lower molars, enamel was significantly thicker at the hypoconid than at the protoconid crown face. The distal face tended to exhibit thicker enamel than either mesial or lingual faces, owing to the thicker hypoconulid enamel. It is suggested that the gradients of thickness within a molar are not necessarily manifested according to direction, but are the result of cusp-specific patterning. The distribution of enamel in the occlusal fovea was found to correspond to the morphology of the outer enamel surface, with the exception of the distinctly thin enamel at and near the tip of the mesiobuccal cusps in both upper and lower molars. The thickness of the enamel in that region might therefore be related to developmental timing or the topography of the enamel-dentine junction, rather than to functional demand. When viewed from a whole-crown, three-dimensional perspective, enamel thickness patterns are in part, but not entirely, explained as an adaptation to functional demand. © 2002 Elsevier Science Ltd. All rights reserved.

An increasing number of studies determine endocranial capacity (ECC) digitally using serial computed tomographic (CT) scan data. However, the multiple causes of errors inherent in such measurements and the resulting degree of accuracy have not yet been fully examined. In the present study, five observers estimated the ECCs of two modern human crania by segmentation of CT data (voxel size 0.380 mm) and by means of the conventional millet seed method. The ECC estimations were much more consistent in the CT-based (technical error, TEM = 1.4 cc) than the millet seed (TEM = 11.8 cc) methods. The estimated capacities also tended to be larger in the latter, suggesting possible systematic bias. Next, the causes and degree of error in the CT-based method were examined. Error due to size calibration of the CT images was no more than 3 cc (± 1.5 cc) per 1000 cc. Errors involved in delineating the endocranial cavity were evaluated as follows. First, we adopted a segmentation routine in which a single global threshold value was applied to most of the volume, and then supplemented locally by more appropriate values in the regions where the global value was insufficient. We then estimated the potential error introduced by choosing a global threshold value. We found this to be within 5 cc (per 1000 cc). This error range increased to 7.5 cc (per 1000 cc), when using a lower resolution data set (slice thickness 1.14 mm). Another source of interobserver error involves the blocking of foramina and canals, which we estimated to be less than 2 cc (per 1000 cc). Adding these various effects, our investigations indicate that ECC estimations based on high-resolution CT data are accurate to within ± 5 cc per 1000 cc. Finally, we reevaluated the ECC of the Minatogawa 1 skull to be 1335 cc (with a probable range of 1327-1343 ± 5 cc), considerably smaller than the originally reported value of 1390 cc obtained by the millet seed method. © 2007 The Anthropological Society of Nippon.

The origin of Australopithecus, the genus widely interpreted as ancestral to Homo, is a central problem in human evolutionary studies. Australopithecus species differ markedly from extant African apes and candidate ancestral hominids such as Ardipithecus, Orrorin and Sahelanthropus. The earliest described Australopithecus species is Au. anamensis, the probable chronospecies ancestor of Au. afarensis. Here we describe newly discovered fossils from the Middle Awash study area that extend the known Au. anamensis range into northeastern Ethiopia. The new fossils are from chronometrically controlled stratigraphic sequences and date to about 4.1-4.2 million years ago. They include diagnostic craniodental remains, the largest hominid canine yet recovered, and the earliest Australopithecus femur. These new fossils are sampled from a woodland context. Temporal and anatomical intermediacy between Ar. ramidus and Au. afarensis suggest a relatively rapid shift from Ardipithecus to Australopithecus in this region of Africa, involving either replacement or accelerated phyletic evolution. © 2006 Nature Publishing Group.

The extremely small endocranial volume (ECV) of LB1, the type specimen of Homo floresiensis, poses a challenge in our understanding of human brain evolution. Some researchers hypothesize dramatic dwarfing of relative brain size from Homo erectus presumably without significant decrease in intellectual function, whereas others expect a lesser degree of brain diminution from a more primitive, small-brained form of hominin currently undocumented in eastern Asia. However, inconsistency in the published ECVs for LB1 (380-430 cc), unclear human intraspecific brain-body size scaling and other uncertainties have hampered elaborative modeling of its brain size reduction. In this study, we accurately determine the ECV of LB1 using high-resolution micro-CT scan. The ECV of LB1 thus measured, 426 cc, is larger than the commonly cited figure in previous studies (400 cc). Coupled with brain-body size correlation in Homo sapiens calculated based on a sample from 20 worldwide modern human populations, we construct new models of the brain size reduction in the evolution of H. floresiensis. The results show a more significant contribution of scaling effect than previously claimed. © 2013 The Author(s) Published by the Royal Society. All rights reserved.

© 2014 Elsevier Ltd and INQUA. In this paper we examine the change in the composition of the Pleistocene primate fauna in southern China based on about 3600 fossil teeth collected from 14 cave sites in Chongzuo area, Guangxi Zhuang Autonomous Region. Although it is often difficult to identify the taxonomic position of isolated Pleistocene primate teeth, nine genera were provisionally identified: Homo, Gigantopithecus, Pongo and Nomascus (Hominoidea), Procynocephalus, Macaca, Rhinopithecus, Pygathrix, and Trachypithecus (Cercopithecoidea). Among these genera, all but Gigantopithecus and Procynocephalus are extant, some of which are not presently distributed in Chongzuo and its neighboring area. More than half of the primate specimens belong to Macaca, which probably includes three to five species, while other genera likely consist of single species. There is a possibility that some of the early macaque species may have been replaced by later members of the genus.All primate genera make their first appearance in the Early Pleistocene, seven of which likely survived until the Holocene in Chongzuo. The extinctions of Procynocephalus and Gigantopithecus are probably due to different factors. The former was likely adapted to cooler and drier environments, and distributed mainly in the area of relatively high latitude. The Early Pleistocene fossil record at Chongzuo is its southernmost occurrence and it may be the youngest record in eastern Eurasia. The latter was a common taxon during the Early Pleistocene, but it disappeared in the early Late Pleistocene. This was probably due to vegetational change, including the loss of their preferred diet, such as bamboo.

© 2015 The Anthropological Society of Nippon. Dental remains of Homo floresiensis excavated during 2002–2004 at Liang Bua, Flores, Indonesia, consist of one partial maxillary dentition, two nearly complete mandibular dentitions, and four isolated teeth. We present here morphological descriptions of all these specimens and report aspects of their dentition, occlusion, and oral health condition. This dental assemblage represents probably five but possibly four or six individuals. These different individuals share similar dental characteristics, supporting the view that the Liang Bua H. floresiensis assemblage represents a single population. We also reassess the previous claims for primitive and modern aspects of the H. floresiensis teeth. The previous studies reached conflicting conclusions: some researchers claim that these teeth are fully modern, whereas others highlight premolar and other morphologies that suggest their direct evolutionary link with the African earliest form of Homo or Australopithecus rather than with H. erectus. Neither of these views are supported. The H. floresiensis teeth exhibit a mosaic of primitive, derived, and unique characters, with the reported primitive aspects broadly comparable to the morphologies observed in H. erectus sensu lato. Although a more comprehensive comparative analysis is needed to fully illustrate dental morphological affinities of this dwarfed hominin species, we find no grounds for the hypothesis that H. floresiensis originated from the small-bodied, primitive hominins such as H. habilis sensu lato.