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Papers - Kono, Reiko

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3D Digital reconstruction, preliminary morphometric analysis, and facial approximation of Shiraho 4 skull

河野礼子, 岡崎健治, 仲座久宜, 徳嶺里江, 片桐千亜紀, 土肥直美

Anthropological Science (Japanese Series) 126 15 - 36 2018.04

Research paper (scientific journal), Joint Work, Accepted

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Various examples of 3D printer usage in natural sciences

河野　礼子

The Hiyoshi review of natural science 2018

Single Work

A mandible from the Middle Pleistocene Hexian site and its significance in relation to the variability of Asian Homo erectus

Liu W., Martinón-Torres M., Kaifu Y., Wu X., Kono R., Chang C., Wei P., Xing S., Huang W., Bermúdez de Castro J.

American Journal of Physical Anthropology (American Journal of Physical Anthropology) 162 ( 4 ) 715 - 731 2017.04

ISSN 00029483

© 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.

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Early Jomon and Yayoi human skeletal remains from Shimomotoyama Rock Shelter, Sasebo, Nagasaki prefecture, Japan

海部陽介, 坂上和弘, 河野礼子

Anthropological Science (Japanese Series) 2017

Joint Work, Accepted

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Initial and Early Jomon human skeletal remains from Iwashita Doketsu, Sasebo, Nagasaki prefecture, Japan: Were Initial Jomon people ephemeral?

海部陽介, 坂上和弘, 河野礼子

Anthropological Science (Japanese Series) 2017

Joint Work, Accepted

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Homo floresiensis-like fossils from the early Middle Pleistocene of Flores.

Van Den Bergh G., Kaifu Y., Kurniawan I., Kono R., Brumm A., Setiyabudi E., Aziz F., Morwood M.

Nature (Nature) 534 ( 7606 ) 245 - 248 2016.06

Single Work, Accepted, ISSN 00280836

© 2016 Macmillan Publishers Limited. All rights reserved. The evolutionary origin of Homo floresiensis, a diminutive hominin species previously known only by skeletal remains from Liang Bua in western Flores, Indonesia, has been intensively debated. It is a matter of controversy whether this primitive form, dated to the Late Pleistocene, evolved from early Asian Homo erectus and represents a unique and striking case of evolutionary reversal in hominin body and brain size within an insular environment. The alternative hypothesis is that H. floresiensis derived from an older, smaller-brained member of our genus, such as Homo habilis, or perhaps even late Australopithecus, signalling a hitherto undocumented dispersal of hominins from Africa into eastern Asia by two million years ago (2 Ma). Here we describe hominin fossils excavated in 2014 from an early Middle Pleistocene site (Mata Menge) in the So'a Basin of central Flores. These specimens comprise a mandible fragment and six isolated teeth belonging to at least three small-jawed and small-toothed individuals. Dating to ∼0.7 Ma, these fossils now constitute the oldest hominin remains from Flores. The Mata Menge mandible and teeth are similar in dimensions and morphological characteristics to those of H. floresiensis from Liang Bua. The exception is the mandibular first molar, which retains a more primitive condition. Notably, the Mata Menge mandible and molar are even smaller in size than those of the two existing H. floresiensis individuals from Liang Bua. The Mata Menge fossils are derived compared with Australopithecus and H. habilis, and so tend to support the view that H. floresiensis is a dwarfed descendent of early Asian H. erectus. Our findings suggest that hominins on Flores had acquired extremely small body size and other morphological traits specific to H. floresiensis at an unexpectedly early time.

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A fourth mandible and associated dental remains of Gigantopithecus blacki from the Early Pleistocene Yanliang Cave, Fusui, Guangxi, South China

Zhang Y., Jin C., Kono R., Harrison T., Wang W.

Historical Biology (Historical Biology) 28 ( 1-2 ) 95 - 104 2016.02

Single Work, Accepted, ISSN 08912963

© 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 M<inf>2</inf> 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.

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Unique dental morphology of Homo floresiensis and its evolutionary implications

Kaifu Y., Kono R., Sutikna T., Saptomo E., Jatmiko, Awe R.

PLoS ONE (PLoS ONE) 10 ( 11 ) e0141614 2015.11

© 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.

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Descriptions of the dental remains of Homo floresiensis

Kaifu Y., Kono R., Sutikna T., Saptomo E., Jatmiko, Awe R., Baba H.

Anthropological Science (Anthropological Science) 123 ( 2 ) 129 - 145 2015.08

Single Work, Accepted, ISSN 09187960

© 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.

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Evolutionary trend in dental size in Gigantopithecus blacki revisited

Zhang Y., Kono R., Wang W., Harrison T., Takai M., Ciochon R., Jin C.

Journal of Human Evolution (Journal of Human Evolution) 83 91 - 100 2015.06

Single Work, Accepted, ISSN 00472484

© 2015 Elsevier Ltd. Previous analyses of dental size in Gigantopithecus blacki indicated marked sexual dimorphism and a trend towards increasing size through time. These studies were based on a sample of over 700 teeth from five localities excavated prior to 1990. Since then, 12 additional cave sites have been discovered in southern China, yielding hundreds of isolated teeth of G. blacki. Most of these sites are well dated by a combination of biochronology and absolute dating methods, so we now have a much better understanding of the chronology of G. blacki. Here, we reexamine the degree of sexual dimorphism and the question of dental size increase through time in G. blacki based on the expanded collections now available. Our results show that sexual dimorphism is not as marked as indicated in previous studies and confirm earlier analyses suggesting that the postcanine teeth of G.blacki tend to become larger through time from the beginning of the Early Pleistocene to the Middle Pleistocene.

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The first archaic Homo from Taiwan

Chang C., Kaifu Y., Takai M., Kono R., Grün R., Matsu'Ura S., Kinsley L., Lin L.

Nature Communications (Nature Communications) 6 6037 2015.02

Single Work, Accepted

© 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.

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A 3-dimensional assessment of molar enamel thickness and distribution pattern in Gigantopithecus blacki

Kono R., Zhang Y., Jin C., Takai M., Suwa G.

Quaternary International (Quaternary International) 354 46 - 51 2014.12

Single Work, Accepted, ISSN 10406182

© 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.

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Changes in the composition of the Pleistocene primate fauna in southern China

Takai M., Zhang Y., Kono R., Jin C.

Quaternary International (Quaternary International) 354 75 - 85 2014.12

Single Work, Accepted, ISSN 10406182

© 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.

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New 400–320 ka Gigantopithecus blacki remains from Hejiang Cave, Chongzuo City, Guangxi, South China

Zhang Y., Jin C., Cai Y., Kono R., Wang W., Wang Y., Zhu M., Yan Y.

Quaternary International (Quaternary International) 354 35 - 45 2014.12

Single Work, Accepted, ISSN 10406182

© 2013 Elsevier Ltd and INQUA. Gigantopithecus blacki is a typical member of the Stegodon-Ailuropoda faunal complex (sensu lato) that inhabited southern China or, more broadly, mainland Southeast Asia during the Early and Middle Pleistocene. Current evidence indicates that the giant ape became extinct during the Middle Pleistocene. Recently, new remains of Gblacki and associated mammalian fossils have been unearthed from a karst cave site, Hejiang Cave, in Chongzuo City, Guangxi, South China. The age of the Gigantopithecus-bearing depositional unit is estimated to be 400-320ka using 230Th-234U disequilibrium U-series dating of flowstone samples bracketing the deposits. These finds document the latest occurrence of Gigantopithecus and provide potential insights regarding its extinction. Comparisons of dental dimensions between the Hejiang G. blacki remains, more than four hundred isolated teeth from Early Pleistocene localities, and over ninety isolated teeth from local drugstores show that the Hejiang teeth are slightly larger in their buccolingual dimensions. In addition, the crowns of the three unerupted upper premolars differ from those of all of the other Gigantopithecus material in having more complex crenulations. The differences in dental dimensions and morphology are possibly reflective of dietary responses to environmental changes that eventually led to the extinction of Gigantopithecus.

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Possible change in dental morphology in Gigantopithecus blacki just prior to its extinction: Evidence from the upper premolar enamel-dentine junction

Zhang Y., Kono R., Jin C., Wang W., Harrison T.

Journal of Human Evolution (Journal of Human Evolution) 75 166 - 171 2014.10

Single Work, Accepted, ISSN 00472484

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Brain size of Homo floresiensis and its evolutionary implications

Kubo D., Kono R., Kaifu Y.

Proceedings of the Royal Society B, Biological Sciences (Proceedings of the Royal Society B: Biological Sciences) 280 ( 1760 ) 20130338 2013.06

Single Work, Accepted, ISSN 09628452

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.

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Endocranial proportions and postorbital morphology of the Minatogawa I and IV Late Pleistocene Homo sapiens crania from Okinawa Island, Japan

Kubo D., Kono R., Suwa G.

Anthropological Science (Anthropological Science) 120 ( 2 ) 179 - 194 2012.10

Single Work, Accepted, ISSN 09187960

The purpose of this paper is to clarify the endocranial and postorbital morphologies of the terminal Pleistocene Minatogawa people, and obtain insights into their evolutionary background and genealogical relationships. The Minatogawa I and IV crania were compared with 83 Homo sapiens specimens (including 19 prehistoric Jomon). Metric comparative analyses and observational evaluations revealed that the two Minatogawa endocrania are characterized by a common suite of features (or tendency), including a small endocranial volume, relatively low endocranial shape, distinctly broad temporal region (qualitatively associated with the strong temporal bulge), weak parietal boss, and weakly swollen frontal bulge. Postorbital constriction was confirmed to be strong, relative to both upper facial breadth and maximum cranial breadth. Partial correlation analysis and bivariate comparisons were performed to examine the possible associations of Minatogawa's strong postorbital constriction. The results suggest that constriction relative to the face is predominantly due to a large facial breadth (frontal endocranium not so narrow in Minatogawa I), and also in part to strong neuro-orbital disjunction, while constriction relative to the posterior cranium is largely attributable to endocranial shape. Comparisons with modern/recent H. sapiens materials and limited but informative outgroup specimens (Skhul V, and an example of Homo erectus, Daka) suggests that some of the features characteristic of Minatogawa are possibly ancestral retentions of early H. sapiens (e.g. strong temporal bulge, marked postorbital constriction relative to the face), while others are probably derived population features (e.g. a small endocranial volume, weakly swollen frontal bulge, marked postorbital constriction relative to the posterior cranium). In overall endocranial proportions, the Jomon tend to lie closer to Minatogawa than does the modern Japanese, but such morphologies were also found in individuals of other populations, and thus the similarity does not necessarily support the hypothesis of Minatogawa-Jomon genealogical closeness. © 2012 The Anthropological Society of Nippon.

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A micro-CT based study of the endocranial morphology of the Minatogawa I cranium

Kubo D., Kono R., Suwa G.

Anthropological Science (Anthropological Science) 119 ( 2 ) 123 - 135 2011.10

Single Work, Accepted, ISSN 09187960

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.

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Endocranial restoration and volume estimation of the Minatogawa IV cranium using micro-CT and 3D printer systems

Kubo D., Kono R.

Anthropological Science (Anthropological Science) 119 ( 2 ) 203 - 209 2011.10

Single Work, Accepted, ISSN 09187960

The Minatogawa IV cranium is one of three well-preserved Late Pleistocene Homo sapiens crania from the Minatogawa fissure site, Okinawa Island. This cranium is more damaged than Minatogawa I and exhibits some clear post-mortem distortion. We reconstructed the endocranium of this specimen after correcting the distortion and breakage by combining digital and manual restoration procedures, and established a reliable estimate for its endocranial volume (ECV) to be around 1170 cc. As with the case of Minatogawa I, this result confirmed the suggestion of previous work that the Minatogawa series has small ECVs compared with modern Japanese and Jomon populations. Some dental and osteological conditions, such as heavy tooth wear as well as Harris's lines of the long bones, suggest a possibility that the small ECV of the Minatogawa people as well as their short stature might have been caused in part by a stunting of growth due to undernutrition and possibly a microevolutionary adaptation to the food-limited insular environments. © 2011 The Anthropological Society of Nippon.

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Late Pleistocene modern human mandibles from the Minatogawa Fissure site, Okinawa, Japan: morphological affinities and implications for modern human dispersals in East Asia

Kaifu Y., Fujita M., Kono R., Baba H.

Anthropological Science (Anthropological Science) 119 ( 2 ) 137 - 157 2011.10

Single Work, Accepted, ISSN 09187960

The Late Pleistocene modern human skeletal remains from the Minatogawa Fissure site, Okinawa, are important because of their exceptional completeness. This paper presents the first detailed morphological description of the five mandibular specimens from Minatogawa, which probably belong to two male and two female individuals (two of the five specimens likely belong to the same male individual). Intensive metric and non-metric comparisons with the mandibles of the Jomon Holocene hunter-gatherers from mainland Japan indicate that the Minatogawa mandibles are different from the Jomon condition in many respects: a tendency toward alveolar prognathism, relatively rounded chin morphology, low anterior corpus heights, a large mental foramen, a small ramus, etc. The Jomon mandibles show chronological and geographic variations in some of these traits, but the morphology of Minatogawa is distinct even if such variations are taken into consideration. These observations caution against uncritical acceptance of the traditional view that supposes genealogical relationships between Minatogawa and Jomon. Some characteristics of the Minatogawa mandibles (e.g. alveolar prognathism and relatively small ramus) are shared with Australo-Melanesians, among other modern human populations. Based on these findings, we hypothesize that the Minatogawa people were derived from prehistoric Southeast Asian populations with Australo-Melanesian affinities. © 2009 The Anthropological Society of Nippon.

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Mandibular tooth root size in modern Japanese, prehistoric Jomon, and Late Pleistocene Minatogawa human fossils

Suwa G., Fukase H., Kono R., Kubo D., Fujitakubo M.

Anthropological Science (Anthropological Science) 119 ( 2 ) 159 - 171 2011.10

Single Work, Accepted, ISSN 09187960

Although dental size and morphology have contributed to population history studies in Japan, little attention has been paid to root size and dimensions. We report here computer tomography (CT)-based metrics of mandibular tooth roots in modern Japanese, Holocene Jomon, and Late Pleistocene Minatogawa human fossils (15000-20000 BP). Our results confirmed that, in terms of both mesiodistal cervical diameters and root lengths, the Jomon is overall smaller-toothed, with summed mesiodistal cervical diameters 4% smaller than in the modern Japanese. However, no significant differences were found in the M1, in both cervical diameter and root length. These results are comparable to the crown size differences reported in the two populations. There were no significant differences in root proportions (root length relative to cervical diameter) between the Jomon and the modern Japanese in each tooth element from I1 to M1, while an allometric root length reduction was observed in the M2 and M3 of the modern Japanese. This reflects distinct patterns of dental reduction in the two populations. The Late Pleistocene Minatogawa fossils were found to have larger cervical diameters and root lengths than either the modern Japanese or the Jomon, in some respects approximating the largetoothed Australian and/or earlier Late Pleistocene Homo sapiens conditions. This indicates a largely conservative dental system retained in the Minatogawa fossils, distinct from the Jomon condition. © 2011 The Anthropological Society of Nippon.

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デジタル解析からみた港川人

河野　礼子

科学 80 ( 4 ) 378 - 380 2010

Single Work

Paleobiological implications of the Ardipithecus ramidus dentition.

Suwa G., Kono R., Simpson S., Asfaw B., Owen Lovejoy C., White T.

Science (Science) 326 ( 5949 ) 94 - 99 2009.10

Single Work, ISSN 00368075

The Middle Awash Ardipithecus ramidus sample comprises over 145 teeth, including associated maxillary and mandibular sets. These help reveal the earliest stages of human evolution. Ar. ramidus lacks the postcanine megadontia of Australopithecus. Its molars have thinner enamel and are functionally less durable than those of Australopithecus but lack the derived Pan pattern of thin occlusal enamel associated with ripe-fruit frugivory. The Ar. ramidus dental morphology and wear pattern are consistent with a partially terrestrial, omnivorous/frugivorous niche. Analyses show that the ARA-VP-6/500 skeleton is female and that Ar. ramidus was nearly monomorphic in canine size and shape. The canine/lower third premolar complex indicates a reduction of canine size and honing capacity early in hominid evolution, possibly driven by selection targeted on the male upper canine.

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The Ardipithecus ramidus skull and its implications for hominid origins.

Suwa G., Asfaw B., Kono R., Kubo D., Owen Lovejoy C., White T.

Science (Science) 326 ( 5949 ) 2009.10

Single Work, ISSN 00368075

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.

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Tomographic analysis of the Daka calvaria

Gilbert W., Holloway R., Kubo D., Kono R., Suwa G.

Homo erectus: Pleistocene Evidence from the Middle Awash, Ethiopia (Homo erectus: Pleistocene Evidence from the Middle Awash, Ethiopia) 329 - 347 2009.02

ISSN 9780520251205

Accuracy and precision of CT-based endocranial capacity estimations: a comparison with the conventional millet seed method and application to the Minatogawa 1 skull.

DAISUKE KUBO, REIKO T. KONO, AIKO SASO, SOUICHIRO MIZUSHIMA, GEN SUWA

Anthropological Science (Anthropological Science) 116 ( 1 ) 77 - 85 2008.05

Single Work, ISSN 09187960

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.

Enamel distribution patterns of extant human and hominoid molars: occlusal versus lateral enamel thickness.

河野　礼子

Bulletin of the National Museum of Nature and Science, Series D (Anthropology) 34 1 - 9 2008

Single Work

A new species of great ape from the late Miocene epoch in Ethiopia

SUWA Gen, KONO Reiko T., KATOH Shigehiro, ASFAW Berhane, BEYENE Yonas

Nature (Nature) 448 ( 7156 ) 921 - 924 2007.08

Joint Work, ISSN 00280836

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.

Asa Issie, Aramis and the origin of Australopithecus

White T., WoldeGabriel G., Asfaw B., Ambrose S., Beyene Y., Bernor R., Boisserie J., Currie B., Gilbert H., Haile-Selassie Y., Hart W., Hlusko L., Howell F., Kono R., Lehmann T., Louchart A., Lovejoy C., Renne P., Saegusa H., Vrba E., Wesselman H., Suwa G.

Nature (Nature) 440 ( 7086 ) 883 - 889 2006.04

Single Work, ISSN 00280836

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.

A micro-CT based study of linear enamel thickness in the mesial cusp section of human molars: reevaluation of methodology and assessment of within-tooth, serial, and individual variation.

GEN SUWA, REIKO T. KONO

Anthropological Science (Anthropological Science) 113 ( 3 ) 273 - 289 2005.12

Joint Work, ISSN 09187960

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.

Effects of molar crown orientation to measures of lateral enamel thickness in the mesial cusp section.

河野　礼子

Bulletin of the National Science Museum, Series D (Anthropology) 31 11 - 22 2005

Single Work

Molar enamel thickness and distribution patterns in extant great apes and humans: new insights based on a 3-dimensional whole crown perspective

REIKO T. KONO

Anthropological Science (Anthropological Science) 112 ( 2 ) 121 - 146 2004.08

Single Work, ISSN 09187960

Molar enamel thickness is a key feature in the study of hominid evolution. Our understanding of enamel thickness and distribution patterns, however, has so far been based mostly on the limited information available from physical cross sections of the crown. In this study, the 3-dimensional (3D) whole crown enamel distribution pattern was explored in 74 extant great ape and modern human molars. Serial cross sections obtained from microfocal X-ray computed tomography were used to generate digital molar reconstructions at 50 to 80 micron voxel resolution, each crown represented by two to five million voxels. Surface data of both enamel dentine junction (EDJ) and outer enamel were extracted to derive volumetric measures, surface areas, curvilinear distances, and whole crown radial thickness maps. Three-dimensional average enamel thickness (AET) was defined as enamel volume divided by EDJ surface area. In 3D AET relative to tooth size, Homo exhibited the thickest, Gorilla the thinnest, and Pan and Pongo intermediately thick enamel. This result differs from previous claims that molar enamel of Pongo is relatively thicker than that of Pan. The discrepancy between three and two-dimensional (2D) values of AET stems from a combination of local differences in within tooth enamel distribution pattern and EDJ topography between Pan and Pongo molars. It demonstrates that 2D AET is not an appropriate substitute or estimator of whole crown AET. Examination of whole crown 3D distributions of molar enamel revealed a pattern common to all four examined species, the "functional" side of the molar having thicker enamel than the opposite side. However, some unique aspects of each species were also apparent. While the Gorilla molar has relatively thin enamel throughout its crown, Pan molars are characterized by particularly thin enamel in the occlusal fovea, and Pongo molars by an accentuation of relatively thin basal and thick occlusal enamel. Human molars are characterized by relatively thick enamel throughout the crown, with relatively large contrasts between buccal and lingual, and between mesial and distal crown portions. The ancestral condition common to the four extant species can be estimated by interpreting molar enamel distribution patterns unique to each genus as likely to be derived. We hypothesize that the last common ancestor likely had intermediately thick enamel, without particular thickening (or thinning) of enamel either occlusally or basally.

Genetics and the evolution of primate enamel thickness: A baboon model

Hlusko L., Suwa G., Kono R., Mahaney M.

American Journal of Physical Anthropology (American Journal of Physical Anthropology) 124 ( 3 ) 223 - 233 2004.07

Single Work, ISSN 00029483

The thickness of mammalian tooth enamel plays a prominent role in paleontology because it correlates with diet, and thicker enamel protects against tooth breakage and wear. Hominid evolutionary studies have stressed the importance of this character for over 30 years, from the identification of "Ramapithecus" as an early Miocene hominid, to the recent discovery that the earliest hominids display molar enamel intermediate in thickness between extant chimpanzees and Australopithecus. Enamel thickness remains largely unexplored for nonhominoid primate fossils, though there is significant variation across modern species. Despite the importance of enamel thickness variation to primate evolution, the mechanisms underlying variation in this trait have not yet been elucidated. We report here on the first quantitative genetic analysis of primate enamel thickness, an analysis based on 506 pedigreed baboons from a captive breeding colony. Computed tomography analysis of 44 Papio mandibular molars shows a zone of sufficiently uniform enamel thickness on the lateral surface of the protoconid. With this knowledge, we developed a caliper metric measurement protocol for use on baboon molars worn to within this zone, enabling the collection of a data set large enough for genetic analyses. Quantitative genetic analyses show that a significant portion of the phenotypic variance in enamel thickness is due to the additive effects of genes and is independent of sex and tooth size. Our models predict that enamel thickness could rapidly track dietary adaptive shifts through geological time, thus increasing the potential for homoplasy in this character. These results have implications for analyses of hominoid enamel thickness variation, and provide a foundation from which to explore the evolution of this phenotype in the papionin fossil record. © 2004 Wiley-Liss, Inc.

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Plio-Pleistocene terrestrial mammal assemblage from Konso, southern Ethiopia

Suwa G., Nakaya H., Asfaw B., Saegusa H., Amzaye A., Kono R., Beyene Y., Katoh S.

Journal of Vertebrate Paleontology (Journal of Vertebrate Paleontology) 23 ( 4 ) 901 - 916 2003.12

Single Work, ISSN 02724634

Mammalian fossils of the Konso Formation (southwestern Main Ethiopian Rift) derive from stratigraphic intervals dated to between 2.0 Ma and younger than 1.3 Ma. Systematic paleontological collecting resulted in almost 8, 000 identifiable mammalian specimens representing 8 orders, 22 families, and more than 68 species including Australopithecus boisei and Homo erectus. Despite geographic proximity to the Turkana Basin (approximately 200 km), aspects of the Konso fauna are distinctive, with its 1.9–1.7 Ma assemblage showing some degree of endemism. Bovids Megalotragus, Parmularius altidens, Parmularius eppsi, Menelikia, and Pelorovis, all common at Turkana and/or Olduvai, are rare or absent at Konso, while Parmularius cf. pandatus, Simatherium, and Notochoerus n. sp. of the Konso assemblages are the youngest known records of these taxa in eastern Africa. The dominant suid of this assemblage is Kolpochoerus majus, a previously poorly known taxon. Subsequent to circa 1.7 Ma, an influx of external elements occurred, possibly related to a general East African trend of climatic drying between 1.8 and 1.6 Ma. The post-1.5 Ma Konso fauna is characterized by apparently immigrant dry grassland adapted bovids, such as Damaliscus niro and Parmularius angustieomis. Metridiochoerus compactus, Metridiochoerus hopwoodi and Metridiochoerus modestus are common in the 1.5 to 1.3 Ma levels at Konso, whereas the latter two suids are rare at Turkana. The post-1.5 Ma Kolpochoerus limneteslolduvaiensis of Konso is morphologically more conservative than time-equivalent Turkana specimens. The post-1.5 Ma Konso Elephas rechi represents an evolutionary grade immediately preceding the fully advanced E. rechi rechi condition. © 2003 by the Society of Vertebrate Paleontology.

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Homo erectus calvarium from the Pleistocene of Java

Baba H., Aziz F., Kaifu Y., Suwa G., Kono R., Jacobs T.

Science (Science) 299 ( 5611 ) 1384 - 1388 2003.02

Single Work, ISSN 00368075

A Homo erectus calvarium [Sambungmacan 4 (Sm 4)] was recovered from Pleistocene sediments at Sambungmacan in central Java. Micro-computed tomography analysis shows a modern human-like cranial base flexion associated with a low platycephalic vault, implying that the evolution of human cranial gobularity was independent of cranial base flexion. The overall morphology of Sm 4 is intermediate between that of earlier and later Javanese Homo erectus; apparent morphological specializations are more strongly expressed in the latter. This supports the hypothesis that later Pleistocene Javanese populations were substantially isolated and made minimal contributions to the ancestry of modern humans.

Comparison of intercusp distances between mandibular molars of Pan troglodytes and Homo sapiens

河野　礼子

Bulletin of the National Science Museum, Series D (Anthropology) 29 1 - 10 2003

Single Work

A three-dimensional analysis of enamel distribution patterns in human permanent first molars

Kono R., Suwa G., Tanijiri T.

Archives of Oral Biology (Archives of Oral Biology) 47 ( 12 ) 867 - 875 2002.12

ISSN 00039969

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.

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A refined method of measuring basal crown and Cusp areas by use of a three-dimensional digitizing system

Suwa G., Kono-Takeuchi R.

Anthropological Science (Anthropological Science) 106 ( SUPPL. ) 95 - 105 1998.12

ISSN 09187960

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.

A new method of evaluating enamel thickness based on a three-dimensional measuring system

Kono-Takeuchi R., Suwa G., Kanazawa E., Tanijiri T.

Anthropological Science (Anthropological Science) 105 ( 4 ) 217 - 229 1997.10

ISSN 09187960

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.

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