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Šimková PG, Wurm L, Fornai C, Krenn VA, Weber GW. Shape variation in modern human upper premolars. PLoS One 2024; 19:e0301482. [PMID: 38593117 PMCID: PMC11003632 DOI: 10.1371/journal.pone.0301482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 03/16/2024] [Indexed: 04/11/2024] Open
Abstract
Morphological variation in modern human dentition is still an open field of study. The understanding of dental shape and metrics is relevant for the advancement of human biology and evolution and is thus of interest in the fields of dental anthropology, as well as human anatomy and medicine. Of concern is also the variation of the inner aspects of the crown which can be investigated using the tools and methods of virtual anthropology. In this study, we explored inter- and intra-population morphometric variation of modern humans' upper third and fourth premolars (P3s and P4s, respectively) considering both the inner and outer aspects of the crown, and discrete traits. We worked by means of geometric morphometrics on 3D image data from a geographically balanced sample of human populations from five continents, to analyse the shape of the dentinal crown, and the crown outline in 78 P3s and 76 P4s from 85 individuals. For the study of dental traits, we referred to the Arizona State University Dental Anthropology System integrated with more recent classification systems. The 3D shape variation of upper premolar crowns varied between short and mesio-distally broad, and tall and mesio-distally narrow. The observed shape variation was independent from the geographical origin of the populations, and resulted in extensive overlap. We noted a high pairwise correlation (r1 = 0.83) between upper P3s and P4s. We did not find any significant geographic differences in the analysed non-metric traits. Our outcomes thus suggest that geographical provenance does not play a determinant role in the shaping of the dental crown, whose genesis is under strict genetic control.
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Affiliation(s)
- Petra G. Šimková
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
- Human Evolution and Archaeological Sciences HEAS, University of Vienna, Vienna, Austria
| | - Lisa Wurm
- Medical Technology Cluster, Business Upper Austria–OÖ Wirtschaftsagentur GmbH, Linz, Austria
| | - Cinzia Fornai
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
- Human Evolution and Archaeological Sciences HEAS, University of Vienna, Vienna, Austria
- Department of Research in Occlusion Medicine, Vienna School of Interdisciplinary Dentistry–VieSID, Klosterneuburg, Austria
- Center for Clinical Research, University Clinic of Dentistry Vienna, Medical University of Vienna, Vienna, Austria
- Institute of Evolutionary Medicine, University of Zurich, Zürich, Switzerland
| | - Viktoria A. Krenn
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
- Institute of Evolutionary Medicine, University of Zurich, Zürich, Switzerland
- Fraunhofer Austria Research GmbH, Graz, Austria
| | - Gerhard W. Weber
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
- Human Evolution and Archaeological Sciences HEAS, University of Vienna, Vienna, Austria
- Core Facility for Micro-Computed Tomography, University of Vienna, Vienna, Austria
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2
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Chapple SA, Skinner MM. A tooth crown morphology framework for interpreting the diversity of primate dentitions. Evol Anthropol 2023; 32:240-255. [PMID: 37486115 DOI: 10.1002/evan.21994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 03/25/2023] [Accepted: 06/19/2023] [Indexed: 07/25/2023]
Abstract
Variation in tooth crown morphology plays a crucial role in species diagnoses, phylogenetic inference, and the reconstruction of the evolutionary history of the primate clade. While a growing number of studies have identified developmental mechanisms linked to tooth size and cusp patterning in mammalian crown morphology, it is unclear (1) to what degree these are applicable across primates and (2) which additional developmental mechanisms should be recognized as playing important roles in odontogenesis. From detailed observations of lower molar enamel-dentine junction morphology from taxa representing the major primate clades, we outline multiple phylogenetic and developmental components responsible for crown patterning, and formulate a tooth crown morphology framework for the holistic interpretation of primate crown morphology. We suggest that adopting this framework is crucial for the characterization of tooth morphology in studies of dental development, discrete trait analysis, and systematics.
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Affiliation(s)
- Simon A Chapple
- School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Matthew M Skinner
- School of Anthropology and Conservation, University of Kent, Canterbury, UK
- Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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3
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Zhou Y, Tao Y. Endodontic management of maxillary first molar with protostylid: a rare case report. BMC Oral Health 2023; 23:606. [PMID: 37644464 PMCID: PMC10467028 DOI: 10.1186/s12903-023-03315-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/14/2023] [Indexed: 08/31/2023] Open
Abstract
BACKGROUND A protostylid is a relatively rare dental developmental aberration characterized as an extra cusp located on the mesial half of the buccal surface of the molars. A protostylid is rarely to be reported due to its low rate of occurrence. This case report describes a patient referred for endodontic treatment due to the presence of a protostylid on the buccal surface of the maxillary first molar that induced apical periodontitis. CASE PRESENTATION A 53-year-old female reported a 3-month history of pain of chewing with her upper left posterior teeth over 3 months. In the clinical examination, an abraded anomalous cusp-like structure was found on the buccal surface of tooth 26, Cone beam computed tomography (CBCT) revealed a supernumerary cusp with an intact root canal inside, which was fused with the mesiobuccal (MB) root canal in the middle of the root. In addition, extensive periapical radiolucency was observed around tooth 26. The tooth was diagnosed as apical periodontitis, and endodontic treatment was performed. The initial lesion in tooth 26 gradually healed over 1 year of observation. CONCLUSIONS To our knowledge, this case is the first to describe the endodontic management of a maxillary first molar with a protostylid and advances our understanding of supernumerary cusps. This case provides a reference for the treatment of protostylid.
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Affiliation(s)
- Yang Zhou
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-Sen University, No.56, Lingyuan West Road, Guangzhou, 510055, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China
| | - Ye Tao
- Hospital of Stomatology, Guanghua School of Stomatology, Sun Yat-Sen University, No.56, Lingyuan West Road, Guangzhou, 510055, China.
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-Sen University, Guangzhou, China.
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4
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Delezene LK, Skinner MM, Bailey SE, Brophy JK, Elliott MC, Gurtov A, Irish JD, Moggi-Cecchi J, de Ruiter DJ, Hawks J, Berger LR. Descriptive catalog of Homo naledi dental remains from the 2013 to 2015 excavations of the Dinaledi Chamber, site U.W. 101, within the Rising Star cave system, South Africa. J Hum Evol 2023; 180:103372. [PMID: 37229947 DOI: 10.1016/j.jhevol.2023.103372] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 03/31/2023] [Accepted: 03/31/2023] [Indexed: 05/27/2023]
Abstract
More than 150 hominin teeth, dated to ∼330-241 thousand years ago, were recovered during the 2013-2015 excavations of the Dinaledi Chamber of the Rising Star cave system, South Africa. These fossils comprise the first large single-site sample of hominin teeth from the Middle Pleistocene of Africa. Though scattered remains attributable to Homo sapiens, or their possible lineal ancestors, are known from older and younger sites across the continent, the distinctive morphological feature set of the Dinaledi teeth supports the recognition of a novel hominin species, Homo naledi. This material provides evidence of African Homo lineage diversity that lasts until at least the Middle Pleistocene. Here, a catalog, anatomical descriptions, and details of preservation and taphonomic alteration are provided for the Dinaledi teeth. Where possible, provisional associations among teeth are also proposed. To facilitate future research, we also provide access to a catalog of surface files of the Rising Star jaws and teeth.
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Affiliation(s)
- Lucas K Delezene
- Department of Anthropology, University of Arkansas, Fayetteville, AR 72701, USA; Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa.
| | - Matthew M Skinner
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa; School of Anthropology and Conservation, University of Kent, Marlowe Building, Canterbury CT2 7NR, UK; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Shara E Bailey
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany; Department of Anthropology, Center for the Study of Human Origins, New York University, New York, NY 10003, USA
| | - Juliet K Brophy
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa; Department of Geography and Anthropology, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Marina C Elliott
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa; Department of Archaeology, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, USA
| | - Alia Gurtov
- Stripe, Inc., 199 Water Street, 30th Floor, New York, NY 10038, USA
| | - Joel D Irish
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa; School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Jacopo Moggi-Cecchi
- Laboratory of Anthropology, Department of Biology, University of Florence, Via del Proconsolo 12, Firenze 50122, Italy
| | - Darryl J de Ruiter
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa; Department of Anthropology, Texas A&M University, College Station, TX 77843, USA
| | - John Hawks
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa; Department of Anthropology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Lee R Berger
- National Geographic Society, 1145 17th Street NW, Washington, DC 20036, USA; Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa
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5
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Chapple SA, Skinner MM. Primate tooth crown nomenclature revisited. PeerJ 2023; 11:e14523. [PMID: 36650833 PMCID: PMC9840859 DOI: 10.7717/peerj.14523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 11/15/2022] [Indexed: 01/15/2023] Open
Abstract
Cusp patterning on living and extinct primate molar teeth plays a crucial role in species diagnoses, phylogenetic inference, and the reconstruction of the evolutionary history of the primate clade. These studies rely on a system of nomenclature that can accurately identify and distinguish between the various structures of the crown surface. However, studies at the enamel-dentine junction (EDJ) of some primate taxa have demonstrated a greater degree of cusp variation and expression at the crown surface than current systems of nomenclature allow. In this study, we review the current nomenclature and its applicability across all the major primate clades based on investigations of mandibular crown morphology at the enamel-dentine junction revealed through microtomography. From these observations, we reveal numerous new patterns of lower molar accessory cusp expression in primates. We highlight numerous discrepancies between the expected patterns of variation inferred from the current academic literature, and the new patterns of expected variation seen in this study. Based on the current issues associated with the crown nomenclature, and an incomplete understanding of the precise developmental processes associated with each individual crown feature, we introduce these structures within a conservative, non-homologous naming scheme that focuses on simple location-based categorisations. Until there is a better insight into the developmental and phylogenetic origin of these crown features, these categorisations are the most practical way of addressing these structures. Until then, we also suggest the cautious use of accessory cusps for studies of taxonomy and phylogeny.
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Affiliation(s)
- Simon A. Chapple
- School of Anthropology and Conservation, University of Kent at Canterbury, Canterbury, Kent, United Kingdom
| | - Matthew M. Skinner
- School of Anthropology and Conservation, University of Kent at Canterbury, Canterbury, Kent, United Kingdom,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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6
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Kato A, Hori M, Hori T, Jincho M, Sekine H, Kawai T. Generating Training Data Using Python Scripts for Automatic Extraction of Landmarks from Tooth Models. J HARD TISSUE BIOL 2022. [DOI: 10.2485/jhtb.31.95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Akiko Kato
- Department of Oral Anatomy, School of Dentistry, Aichi Gakuin University
| | - Miki Hori
- Department of Dental Materials Science, School of Dentistry, Aichi Gakuin University
| | - Tadasuke Hori
- Center for Advanced Oral Science, School of Dentistry, Aichi Gakuin University
| | - Makoto Jincho
- Center for Advanced Oral Science, School of Dentistry, Aichi Gakuin University
| | - Hironao Sekine
- Center for Advanced Oral Science, School of Dentistry, Aichi Gakuin University
| | - Tatsushi Kawai
- Department of Dental Materials Science, School of Dentistry, Aichi Gakuin University
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7
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Grine FE, Gonzalvo E, Rossouw L, Holt S, Black W, Braga J. Variation in Middle Stone Age mandibular molar enamel-dentine junction topography at Klasies River Main Site assessed by diffeomorphic surface matching. J Hum Evol 2021; 161:103079. [PMID: 34739985 DOI: 10.1016/j.jhevol.2021.103079] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 09/07/2021] [Accepted: 09/12/2021] [Indexed: 11/19/2022]
Abstract
The morphology and variability of the Middle Stone Age (MSA) hominin fossils from Klasies River Main Site have been the focus of investigation for more than four decades. The mandibular remains have figured prominently in discussions relating to robusticity, size dimorphism, and symphyseal morphology. Variation in corpus size between the robust SAM-AP 6223 and the diminutive SAM-AP 6225 mandibles is particularly impressive, and the difference between the buccolingual diameters of their M2s significantly exceeds recent human sample variation. SAM-AP 6223 and SAM-AP 6225 are the only Klasies specimens with homologous teeth (M2 and M3) that permit comparisons of crown morphology. While the differences in dental trait expression at the outer enamel surfaces of these molars are slight, diffeomorphic surface analyses of their underlying enamel-dentine junction (EDJ) topographies reveal differences that are well beyond the means of pairwise differences among comparative samples of Later Stone Age (LSA) Khoesan and recent African homologues. The EDJs of both SAM-AP 6225 molars and the SAM-AP 6223 M3 fall outside the envelopes that define the morphospace of these two samples. Although the radiocarbon dated LSA individuals examined here differ by a maximum of some 7000 years, and the two Klasies jaws may differ by perhaps as much as 18,000 years, it is difficult to ascribe their differences to time alone. With reference to the morphoscopic traits by which the SAM-AP 6223 and SAM-AP 6225 EDJs differ, the most striking is the expression of the protoconid cingulum. This is very weakly developed on the SAM-AP 6223 molars and distinct in SAM-AP 6225. As such, this diminutive fossil exhibits a more pronounced manifestation of what is likely a plesiomorphic feature, thus adding to the morphological mosaicism that is evident in the Klasies hominin assemblage. Several possible explanations for the variation and mosaicism in this MSA sample are discussed.
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Affiliation(s)
- Frederick E Grine
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794-4364, USA; Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794-4364, USA.
| | - Elsa Gonzalvo
- Centre d'Anthropobiologie et de Génomique de Toulouse, Université Paul Sabatier Toulouse III, Faculté de Médecine Purpan, 37 Allées Jules Guesde, Toulouse, France
| | - Lloyd Rossouw
- Florisbad Quaternary Research Department, The National Museum, 36 Aliwal Street, Bloemfontein 9300, South Africa
| | - Sharon Holt
- Florisbad Quaternary Research Department, The National Museum, 36 Aliwal Street, Bloemfontein 9300, South Africa
| | - Wendy Black
- Archaeology Unit, Research and Exhibitions Department, Iziko Museums of South Africa, Cape Town, South Africa
| | - José Braga
- Centre d'Anthropobiologie et de Génomique de Toulouse, Université Paul Sabatier Toulouse III, Faculté de Médecine Purpan, 37 Allées Jules Guesde, Toulouse, France; Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, 2050, South Africa
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8
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Compton T, Skinner MM, Humphrey L, Pope M, Bates M, Davies TW, Parfitt SA, Plummer WP, Scott B, Shaw A, Stringer C. The morphology of the Late Pleistocene hominin remains from the site of La Cotte de St Brelade, Jersey (Channel Islands). J Hum Evol 2021; 152:102939. [PMID: 33517134 DOI: 10.1016/j.jhevol.2020.102939] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 12/13/2020] [Accepted: 12/14/2020] [Indexed: 11/29/2022]
Abstract
Thirteen permanent fully erupted teeth were excavated at the Paleolithic site of La Cotte de St Brelade in Jersey in 1910 and 1911. These were all found in the same location, on a ledge behind a hearth in a Mousterian occupation level. They were originally identified as being Neanderthal. A fragment of occipital bone was found in a separate locality in a later season. Recent dating of adjacent sediments gives a probable age of <48 ka. The purpose of this article is to provide an updated description of the morphology of this material and consider its likely taxonomic assignment from comparison with Neanderthal and Homo sapiens samples. One of the original teeth has been lost, and we identify one as nonhominin. At least two adult individuals are represented. Cervix shape and the absence of common Neanderthal traits in several teeth suggest affinities with H. sapiens in both individuals, while crown and root dimensions and root morphology of all the teeth are entirely consistent with a Neanderthal attribution, pointing toward a possible shared Neanderthal and H. sapiens ancestry (the likely date of this material corresponds with the time in which both Neanderthals and H. sapiens were present in Europe). The occipital fragment is stratigraphically more recent and does not exhibit any diagnostic Neanderthal features.
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Affiliation(s)
- Tim Compton
- Centre for Human Evolution Research, Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK.
| | - Matthew M Skinner
- School of Anthropology and Conservation, University of Kent, Canterbury, CT2 7NR, UK; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany
| | - Louise Humphrey
- Centre for Human Evolution Research, Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | - Matthew Pope
- UCL Institute of Archaeology, University College London, 31-34 Gordon Square, London, WC1H 0PY, UK
| | - Martin Bates
- Faculty of Humanities and Performing Arts, University of Wales Trinity St David, Lampeter, Ceredigion, SA48 7ED, UK
| | - Thomas W Davies
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany
| | - Simon A Parfitt
- Centre for Human Evolution Research, Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK; UCL Institute of Archaeology, University College London, 31-34 Gordon Square, London, WC1H 0PY, UK
| | - William P Plummer
- School of Anthropology and Conservation, University of Kent, Canterbury, CT2 7NR, UK
| | - Beccy Scott
- The British Museum, Great Russell Street, London, WC1B 3DG, UK
| | - Andrew Shaw
- Wessex Archaeology, Portway House, Old Sarum Park, Salisbury, Wiltshire, SP4 6EB, UK
| | - Chris Stringer
- Centre for Human Evolution Research, Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK
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9
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Abstract
Teeth have been studied for decades and continue to reveal information relevant to human evolution. Studies have shown that many traits of the outer enamel surface evolve neutrally and can be used to infer human population structure. However, many of these traits are unavailable in archaeological and fossil individuals due to processes of wear and taphonomy. Enamel-dentine junction (EDJ) morphology, the shape of the junction between the enamel and the dentine within a tooth, captures important information about tooth development and vertebrate evolution and is informative because it is subject to less wear and thus preserves more anatomy in worn or damaged specimens, particularly in mammals with relatively thick enamel like hominids. This study looks at the molar EDJ across a large sample of human populations. We assessed EDJ morphological variation in a sample of late Holocene modern humans (n = 161) from archaeological populations using μ-CT biomedical imaging and geometric morphometric analyses. Global variation in human EDJ morphology was compared to the statistical expectations of neutral evolution and "Out of Africa" dispersal modeling of trait evolution. Significant correlations between phenetic variation and neutral genetic variation indicate that EDJ morphology has evolved neutrally in humans. While EDJ morphology reflects population history, its global distribution does not follow expectations of the Out of Africa dispersal model. This study increases our knowledge of human dental variation and contributes to our understanding of dental development more broadly, with important applications to the investigation of population history and human genetic structure.
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10
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Morita W, Morimoto N, Kono RT, Suwa G. Metameric variation of upper molars in hominoids and its implications for the diversification of molar morphogenesis. J Hum Evol 2019; 138:102706. [PMID: 31785453 DOI: 10.1016/j.jhevol.2019.102706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 10/20/2019] [Accepted: 10/20/2019] [Indexed: 11/18/2022]
Abstract
Metameric variation of molar size is in part associated with the dietary adaptations of mammals and results from slight alterations of developmental processes. Humans and great apes exhibit conspicuous variation in tooth morphology both between taxa and across tooth types. However, the manner in which metameric variation in molars emerged among apes and humans via evolutionary alterations in developmental processes remains largely unknown. In this study, we compare the enamel-dentine junction of the upper molars of humans-which closely correlates with morphology of the outer enamel surface and is less affected by wear-with that of the other extant hominoids: chimpanzees, bonobos, gorillas, orangutans, and gibbons. We used the morphometric mapping method to quantify and visualize three-dimensional morphological variation, and applied multivariate statistical analyses. Results revealed the following: 1) extant hominoids other than humans share a common pattern of metameric variation characterized by a largely linear change in morphospace; this indicates a relatively simple graded change in metameric molar shape; 2) intertaxon morphological differences become less distinct from the mesial to distal molars; and 3) humans diverge from the extant ape pattern in exhibiting a distinct metameric shape change trajectory in the morphospace. The graded shape change and lower intertaxon resolution from the mesial to distal molars are consistent with the concept of a 'key' tooth. The common metameric pattern observed among the extant nonhuman hominoids indicates that developmental patterns underlying metameric variation were largely conserved during ape evolution. Furthermore, the human-specific metameric pattern suggests considerable developmental modifications in the human lineage.
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Affiliation(s)
- Wataru Morita
- Developmental Biology Program, Institute of Biotechnology, University of Helsinki, Helsinki, Finland; Department of Oral Functional Anatomy, Faculty of Dental Medicine, Hokkaido University, Hokkaido, Japan.
| | - Naoki Morimoto
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan.
| | - Reiko T Kono
- Faculty of Letters, Keio University, Kanagawa, Japan
| | - Gen Suwa
- The University Museum, The University of Tokyo, Tokyo, Japan
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11
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Bailey SE, Brophy JK, Moggi-Cecchi J, Delezene LK. The deciduous dentition of Homo naledi: A comparative study. J Hum Evol 2019; 136:102655. [DOI: 10.1016/j.jhevol.2019.102655] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 08/06/2019] [Accepted: 08/08/2019] [Indexed: 12/23/2022]
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12
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Davies TW, Delezene LK, Gunz P, Hublin JJ, Skinner MM. Endostructural morphology in hominoid mandibular third premolars: Discrete traits at the enamel-dentine junction. J Hum Evol 2019; 136:102670. [DOI: 10.1016/j.jhevol.2019.102670] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 09/06/2019] [Accepted: 09/06/2019] [Indexed: 12/20/2022]
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13
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Jones MEH, Lucas PW, Tucker AS, Watson AP, Sertich JJW, Foster JR, Williams R, Garbe U, Bevitt JJ, Salvemini F. Neutron scanning reveals unexpected complexity in the enamel thickness of an herbivorous Jurassic reptile. J R Soc Interface 2019; 15:rsif.2018.0039. [PMID: 29899156 PMCID: PMC6030635 DOI: 10.1098/rsif.2018.0039] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 05/18/2018] [Indexed: 11/12/2022] Open
Abstract
Eilenodontines are one of the oldest radiation of herbivorous lepidosaurs (snakes, lizards and tuatara) characterized by batteries of wide teeth with thick enamel that bear mammal-like wear facets. Unlike most reptiles, eilenodontines have limited tooth replacement, making dental longevity particularly important to them. We use both X-ray and neutron computed tomography to examine a fossil tooth from the eilenodontine Eilenodon (Late Jurassic, USA). Of the two approaches, neutron tomography was more successful and facilitated measurements of enamel thickness and distribution. We find the enamel thickness to be regionally variable, thin near the cusp tip (0.10 mm) but thicker around the base (0.15–0.30 mm) and notably greater than that of other rhynchocephalians such as the extant Sphenodon (0.08–0.14 mm). The thick enamel in Eilenodon would permit greater loading, extend tooth lifespan and facilitate the establishment of wear facets that have sharp edges for orally processing plant material such as horsetails (Equisetum). The shape of the enamel dentine junction indicates that tooth development in Eilenodon and Sphenodon involved similar folding of the epithelium but different ameloblast activity.
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Affiliation(s)
- Marc E H Jones
- Department of Earth Sciences, The Natural History Museum, London, UK .,Department of Genetics and Evolution, School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia.,South Australian Museum, North Terrace, Adelaide, South Australia 5001, Australia
| | - Peter W Lucas
- Smithsonian Tropical Research Institute, Balboa, Panama
| | - Abigail S Tucker
- Craniofacial Development and Stem Cell Biology, King's College London, London, UK
| | - Amy P Watson
- Department of Genetics and Evolution, School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
| | - Joseph J W Sertich
- Department of Earth Sciences, Denver Museum of Nature and Science, Denver, CO, USA
| | | | - Ruth Williams
- Department of Adelaide Microscopy, The University of Adelaide, Adelaide, South Australia 5001, Australia
| | - Ulf Garbe
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Sydney, Australia
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Sydney, Australia
| | - Floriana Salvemini
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Sydney, Australia
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14
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Modeling enamel matrix secretion in mammalian teeth. PLoS Comput Biol 2019; 15:e1007058. [PMID: 31141513 PMCID: PMC6541238 DOI: 10.1371/journal.pcbi.1007058] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/29/2019] [Indexed: 11/20/2022] Open
Abstract
The most mineralized tissue of the mammalian body is tooth enamel. Especially in species with thick enamel, three-dimensional (3D) tomography data has shown that the distribution of enamel varies across the occlusal surface of the tooth crown. Differences in enamel thickness among species and within the tooth crown have been used to examine taxonomic affiliations, life history, and functional properties of teeth. Before becoming fully mineralized, enamel matrix is secreted on the top of a dentine template, and it remains to be explored how matrix thickness is spatially regulated. To provide a predictive framework to examine enamel distribution, we introduce a computational model of enamel matrix secretion that maps the dentine topography to the enamel surface topography. Starting from empirical enamel-dentine junctions, enamel matrix deposition is modeled as a diffusion-limited free boundary problem. Using laboratory microCT and synchrotron tomographic data of pig molars that have markedly different dentine and enamel surface topographies, we show how diffusion-limited matrix deposition accounts for both the process of matrix secretion and the final enamel distribution. Simulations reveal how concave and convex dentine features have distinct effects on enamel surface, thereby explaining why the enamel surface is not a straightforward extrapolation of the dentine template. Human and orangutan molar simulations show that even subtle variation in dentine topography can be mapped to the enamel surface features. Mechanistic models of extracellular matrix deposition can be used to predict occlusal morphologies of teeth.
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15
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Krenn VA, Fornai C, Wurm L, Bookstein FL, Haeusler M, Weber GW. Variation of 3D outer and inner crown morphology in modern human mandibular premolars. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 169:646-663. [PMID: 31099892 PMCID: PMC6767701 DOI: 10.1002/ajpa.23858] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 05/02/2019] [Accepted: 05/06/2019] [Indexed: 12/30/2022]
Abstract
Objectives This study explores the outer and inner crown of lower third and fourth premolars (P3, P4) by analyzing the morphological variation among diverse modern human groups. Materials and Methods We studied three‐dimensional models of the outer enamel surface and the enamel–dentine junction (EDJ) from μCT datasets of 77 recent humans using both an assessment of seven nonmetric traits and a standard geometric morphometric (GM) analysis. For the latter, the dental crown was represented by four landmarks (dentine horns and fossae), 20 semilandmarks along the EDJ marginal ridge, and pseudolandmarks along the crown and cervical outlines. Results Certain discrete traits showed significantly different regional frequencies and sexual dimorphism. The GM analyses of both P3s and P4s showed extensive overlap in shape variation of the various populations (classification accuracy 15–69%). The first principal components explained about 40% of shape variance with a correlation between 0.59 and 0.87 of the features of P3s and P4s. Shape covariation between P3s and P4s expressed concordance of high and narrow or low and broad crowns. Conclusions Due to marked intragroup and intergroup variation in GM analyses of lower premolars, discrete traits such as the number of lingual cusps and mesiolingual groove expression provide better geographic separation of modern human populations. The greater variability of the lingual region suggests a dominance of functional constraints over geographic provenience or sex. Additional information about functionally relevant aspects of the crown surface and odontogenetic data are needed to unravel the factors underlying dental morphology in modern humans.
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Affiliation(s)
- Viktoria A Krenn
- Institute of Evolutionary Medicine, University of Zurich, 8057 Zurich, Switzerland.,Department of Evolutionary Anthropology, University of Vienna, 1090 Vienna, Austria
| | - Cinzia Fornai
- Institute of Evolutionary Medicine, University of Zurich, 8057 Zurich, Switzerland.,Department of Evolutionary Anthropology, University of Vienna, 1090 Vienna, Austria
| | - Lisa Wurm
- Department for Clinical Veterinary Medicine, Ludwig-Maximilians University of Munich, 80539 Munich, Germany
| | - Fred L Bookstein
- Department of Evolutionary Anthropology, University of Vienna, 1090 Vienna, Austria.,Department of Statistics, University of Washington, Seattle, WA-98195, Washington, USA
| | - Martin Haeusler
- Institute of Evolutionary Medicine, University of Zurich, 8057 Zurich, Switzerland
| | - Gerhard W Weber
- Department of Evolutionary Anthropology, University of Vienna, 1090 Vienna, Austria.,Core Facility for Micro-Computed Tomography, 1090 Vienna, Austria
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16
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Braga J, Zimmer V, Dumoncel J, Samir C, de Beer F, Zanolli C, Pinto D, Rohlf FJ, Grine FE. Efficacy of diffeomorphic surface matching and 3D geometric morphometrics for taxonomic discrimination of Early Pleistocene hominin mandibular molars. J Hum Evol 2019; 130:21-35. [PMID: 31010541 DOI: 10.1016/j.jhevol.2019.01.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 12/23/2022]
Abstract
Morphometric assessments of the dentition have played significant roles in hypotheses relating to taxonomic diversity among extinct hominins. In this regard, emphasis has been placed on the statistical appraisal of intraspecific variation to identify morphological criteria that convey maximum discriminatory power. Three-dimensional geometric morphometric (3D GM) approaches that utilize landmarks and semi-landmarks to quantify shape variation have enjoyed increasingly popular use over the past twenty-five years in assessments of the outer enamel surface (OES) and enamel-dentine junction (EDJ) of fossil molars. Recently developed diffeomorphic surface matching (DSM) methods that model the deformation between shapes have drastically reduced if not altogether eliminated potential methodological inconsistencies associated with the a priori identification of landmarks and delineation of semi-landmarks. As such, DSM has the potential to better capture the geometric details that describe tooth shape by accounting for both homologous and non-homologous (i.e., discrete) features, and permitting the statistical determination of geometric correspondence. We compare the discriminatory power of 3D GM and DSM in the evaluation of the OES and EDJ of mandibular permanent molars attributed to Australopithecus africanus, Paranthropus robustus and early Homo sp. from the sites of Sterkfontein and Swartkrans. For all three molars, classification and clustering scores demonstrate that DSM performs better at separating the A. africanus and P. robustus samples than does 3D GM. The EDJ provided the best results. P. robustus evinces greater morphological variability than A. africanus. The DSM assessment of the early Homo molar from Swartkrans reveals its distinctiveness from either australopith sample, and the "unknown" specimen from Sterkfontein (Stw 151) is notably more similar to Homo than to A. africanus.
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Affiliation(s)
- José Braga
- Computer-assisted Palaeoanthropology Team, UMR 5288 CNRS-Université de Toulouse (Paul Sabatier), 37 Allées Jules Guesde, 31000 Toulouse, France; Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg 2050, South Africa.
| | - Veronika Zimmer
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria 0001, South Africa; Department of Biomedical Engineering, King's College London, London, UK.
| | - Jean Dumoncel
- Computer-assisted Palaeoanthropology Team, UMR 5288 CNRS-Université de Toulouse (Paul Sabatier), 37 Allées Jules Guesde, 31000 Toulouse, France.
| | - Chafik Samir
- LIMOS, UMR 6158 CNRS-Université Clermont Auvergne, 63173 Aubière, France.
| | - Frikkie de Beer
- South African Nuclear Energy Corporation (NECSA), Pelindaba, North West Province, South Africa.
| | - Clément Zanolli
- Computer-assisted Palaeoanthropology Team, UMR 5288 CNRS-Université de Toulouse (Paul Sabatier), 37 Allées Jules Guesde, 31000 Toulouse, France.
| | - Deborah Pinto
- Computer-assisted Palaeoanthropology Team, UMR 5288 CNRS-Université de Toulouse (Paul Sabatier), 37 Allées Jules Guesde, 31000 Toulouse, France.
| | - F James Rohlf
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA.
| | - Frederick E Grine
- Department of Anthropology, Stony Brook University, Stony Brook, NY 11794, USA; Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794, USA.
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17
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Liao W, Xing S, Li D, Martinón-Torres M, Wu X, Soligo C, Bermúdez de Castro JM, Wang W, Liu W. Mosaic dental morphology in a terminal Pleistocene hominin from Dushan Cave in southern China. Sci Rep 2019; 9:2347. [PMID: 30787352 PMCID: PMC6382942 DOI: 10.1038/s41598-019-38818-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 12/18/2018] [Indexed: 12/27/2022] Open
Abstract
Recent studies reveal high degrees of morphological diversity in Late Pleistocene humans from East Asia. This variability was interpreted as complex demographic patterns with several migrations and possible survival of archaic groups. However, lack of well-described, reliably classified and accurately dated sites has seriously limited understanding of human evolution in terminal Pleistocene. Here we report a 15,000 years-old H. sapiens (Dushan 1) in South China with unusual mosaic features, such as large dental dimensions, cingulum-like structures at the dentine level in the posterior dentition and expression of a “crown buccal vertical groove complex”, all of which are uncommon in modern humans and more typically found in Middle Pleistocene archaic humans. They could represent the late survival of one of the earliest modern humans to settle in an isolated region of southern China and, hence, the retention of primitive-like traits. They could also represent a particularity of this group and, hence, reflect a high degree of regional variation. Alternatively, these features may be the result of introgression from some late-surviving archaic population in the region. Our study demonstrates the extreme variability of terminal Pleistocene populations in China and the possibility of a complex demographic story in the region.
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Affiliation(s)
- Wei Liao
- State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China.,Anthropology Museum of Guangxi, Nanning, 530028, Guangxi, China
| | - Song Xing
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China.,CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China
| | - Dawei Li
- State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, 430074, China.,Anthropology Museum of Guangxi, Nanning, 530028, Guangxi, China
| | - María Martinón-Torres
- Department of Anthropology, University College London (UCL), 14 Taviton Street, London, WC1H 0BW, UK.,National Research Center on Human Evolution (CENIEH), Paseo Sierra de Atapuerca s/n, Burgos, 09002, Spain
| | - Xiujie Wu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China.,CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China
| | - Christophe Soligo
- Department of Anthropology, University College London (UCL), 14 Taviton Street, London, WC1H 0BW, UK
| | - José María Bermúdez de Castro
- Department of Anthropology, University College London (UCL), 14 Taviton Street, London, WC1H 0BW, UK.,National Research Center on Human Evolution (CENIEH), Paseo Sierra de Atapuerca s/n, Burgos, 09002, Spain
| | - Wei Wang
- Institute of Cultural Heritage, Shandong University, 72 Jimo-Binhai Road, Qingdao, 266237, China.
| | - Wu Liu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China. .,CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China.
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18
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Selig KR, López-Torres S, Sargis EJ, Silcox MT. First 3D Dental Topographic Analysis of the Enamel-Dentine Junction in Non-Primate Euarchontans: Contribution of the Enamel-Dentine Junction to Molar Morphology. J MAMM EVOL 2018. [DOI: 10.1007/s10914-018-9440-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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19
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Xing S, Martinón-Torres M, Bermúdez de Castro JM. The fossil teeth of the Peking Man. Sci Rep 2018; 8:2066. [PMID: 29391445 PMCID: PMC5794973 DOI: 10.1038/s41598-018-20432-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 01/18/2018] [Indexed: 01/06/2023] Open
Abstract
This study provides new original data, including the endostructure of most Zhoukoudian H. erectus teeth preserved to date, since the publication of Black in 1927 and Weidenreich in 1937. The new evidence ratifies the similarities of Zhoukoudian with other East Asian mid-Middle Pleistocene hominins such as Hexian and Yiyuan, and allows defining a dental pattern potentially characteristic of this population commonly referred to as classic H. erectus. Given the possible chronological overlaps of classic H. erectus with other archaic Homo, the characterization of this group becomes a key issue when deciphering the taxonomy and evolutionary scenario of the Middle Pleistocene hominins in East Asia. Internally, the most remarkable feature of Zhoukoudian teeth is the highly crenulated enamel-dentine junction (EDJ) and its imprint on the roof of the pulp cavity. So far, this "dendrite-like" EDJ has been found only in East Asia Middle Pleistocene hominins although a large group of samples were assessed, and it could be useful to dentally define classic H. erectus in China. The crenulated EDJ surface, together with the stout roots and the taurodontism could be a mechanism to withstand high biomechanical demand despite a general dentognathic reduction, particularly of the crowns, in these populations.
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Affiliation(s)
- Song Xing
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100044, China.
| | - María Martinón-Torres
- National Research Center on Human Evolution (CENIEH), Paseo de la Sierra de Atapuerca 3, 09002, Burgos, Spain.,University College London (UCL) Anthropology, 14 Taviton Street, London, WC1H 0BW, UK
| | - José María Bermúdez de Castro
- National Research Center on Human Evolution (CENIEH), Paseo de la Sierra de Atapuerca 3, 09002, Burgos, Spain.,University College London (UCL) Anthropology, 14 Taviton Street, London, WC1H 0BW, UK
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20
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Was Mesopithecus a seed eating colobine? Assessment of cracking, grinding and shearing ability using dental topography. J Hum Evol 2017; 112:79-92. [DOI: 10.1016/j.jhevol.2017.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 08/28/2017] [Accepted: 09/05/2017] [Indexed: 11/20/2022]
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21
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Martin RM, Hublin JJ, Gunz P, Skinner MM. The morphology of the enamel–dentine junction in Neanderthal molars: Gross morphology, non-metric traits, and temporal trends. J Hum Evol 2017; 103:20-44. [DOI: 10.1016/j.jhevol.2016.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 12/15/2022]
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22
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Marado LM, Silva AM. The mandibular molar pit-tubercle (MMPT) dental nonmetric trait: Comprehensive analysis of a large sample. HOMO-JOURNAL OF COMPARATIVE HUMAN BIOLOGY 2016; 67:462-470. [PMID: 27890318 DOI: 10.1016/j.jchb.2016.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 08/30/2016] [Indexed: 11/26/2022]
Abstract
Dental nonmetric traits are quasicontinous variables, mostly of genetic origin. Thus, sets of such traits allow biological distance estimation between samples. Mandibular molar pit-tubercle (MMPT) is a buccal trait defined by Weets (2009) in Irish samples. This study aims to analyze (a) trait frequencies, (b) grade definitions, (c) intraobserver error, (d) sexual dimorphism, (e) asymmetry, and (f) trait associations for MMPT in a Portuguese sample. The first (LM1), second (LM2) and third (LM3) lower molars of 600 identified individuals from the Coimbra collections were scored for MMPT in three scoring sessions. Intraobserver error, bilateral asymmetry and trait correlations were tested using Kendall's τ-b, while sexual dimorphism was verified using Pearson's χ2. Frequencies (LM1: 2.1%; LM2: 3.5%; LM3: 30.3%) were similar to previous reports. However, a new free apex cusp form (grade 3+) was detected. Considering three scoring sessions, intraobserver precision was above 85%, and correlation coefficients between observations were positive and moderate to very strong (0.291<τ-b<0.835). Intrasample variation was low, since only LM3 showed sexual dimorphism (female: 30.2%; males: 16.2%; χ2=15.512; p<0.001; df=1; n=556) and large asymmetry (27.1%). There were no strong (τ-b>0.3) intertrait associations involving MMPT. MMPT shows low trait presence, sexual dimorphism and asymmetry in stable teeth (LM1 and LM2). Intraobserver precision is high, so scoring should be reliable, although a plaque and better threshold grade definition is needed. After further research on non-European samples, MMPT can be useful in biodistance research.
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Affiliation(s)
- Luís Miguel Marado
- Lab2PT - Landscape, Heritage and Territory Laboratory, Unit of Archaeology, University of Minho, Portugal.
| | - Ana Maria Silva
- Prehistory Laboratory, CIAS, University of Coimbra, Portugal; UNIARQ - WAPS, University of Lisbon Archaeology Center, Portugal; Laboratory of Forensic Anthropology, Center for Functional Ecology, University of Coimbra, Portugal.
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23
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Morita W. Morphological comparison of the enamel–dentine junction and outer enamel surface of molars using a micro-computed tomography technique. J Oral Biosci 2016. [DOI: 10.1016/j.job.2016.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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24
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Further morphological evidence on South African earliest Homo lower postcanine dentition: Enamel thickness and enamel dentine junction. J Hum Evol 2016; 96:82-96. [DOI: 10.1016/j.jhevol.2016.05.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 05/03/2016] [Accepted: 05/04/2016] [Indexed: 11/23/2022]
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25
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Morita W, Morimoto N, Ohshima H. Exploring metameric variation in human molars: a morphological study using morphometric mapping. J Anat 2016; 229:343-55. [PMID: 27098351 DOI: 10.1111/joa.12482] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2016] [Indexed: 12/01/2022] Open
Abstract
Human molars exhibit a type of metameric variation, which is the difference in serially repeated morphology within an organism. Various theories have been proposed to explain how this variation is brought about in the molars. Actualistic data that support the theories, however, are still relatively scarce because of methodological limitations. Here we propose new methods to analyse detailed tooth crown morphologies. We applied morphometric mapping to the enamel-dentine junction of human maxillary molars and examined whether odontogenetic models were adaptable to human maxillary molars. Our results showed that the upper first molar is phenotypically distinct among the maxillary molars. The average shape of the upper first molar is characterized by four well-defined cusps and precipitous surface relief of the occlusal table. On the other hand, upper third molar is characterized by smooth surface relief of the occlusal table and shows greater shape variation and distinct distribution patterns in morphospace. The upper second molar represents an intermediate state between first and third molar. Size-related shape variation was investigated by the allometric vector analysis, and it appeared that human maxillary molars tend to converge toward the shape of the upper first molar as the size increases. Differences between the upper first molar and the upper second and third molar can thus be largely explained as an effect of allometry. Collectively, these results indicate that the observed pattern of metameric variation in human molars is consistent with odontogenetic models of molar row structure (inhibitory cascade model) and molar crown morphology (patterning cascade model). This study shows that morphometric mapping is a useful tool to visualize and quantify the morphological features of teeth, which can provide the basis for a better understanding of tooth evolution linking morphology and development.
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Affiliation(s)
- Wataru Morita
- Department of Oral Functional Anatomy, Hokkaido University Graduate School of Dental Medicine, Sapporo, Japan.,Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Naoki Morimoto
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Hayato Ohshima
- Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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26
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Moreno S, Reyes MP, Moreno F. Cusp expression of protostylid in deciduous and permanent molars. J Forensic Dent Sci 2016; 8:155-163. [PMID: 28123270 PMCID: PMC5210103 DOI: 10.4103/0975-1475.195108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The present article is a case report on the cusp expression of protostylid in the deciduous inferior molars and in the first permanent inferior molar, in which the correspondence and bilateral symmetry of the mentioned expression can be evidenced, as well as the their relation with the foramen cecum of the mesiobuccal furrows of the deciduous and of the permanent inferior molars.
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Affiliation(s)
- Sandra Moreno
- Department of Basic Health Sciences, Pontificia Universidad Javeriana, Cali, Colombia; School of Dentistry, Universidad del Valle, Cali, Colombia
| | - María Paula Reyes
- School of Medicine, Pontificia Universidad Javeriana, Cali, Colombia
| | - Freddy Moreno
- Department of Basic Health Sciences, Pontificia Universidad Javeriana, Cali, Colombia; School of Dentistry, Universidad del Valle, Cali, Colombia
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27
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Guy F, Lazzari V, Gilissen E, Thiery G. To What Extent is Primate Second Molar Enamel Occlusal Morphology Shaped by the Enamel-Dentine Junction? PLoS One 2015; 10:e0138802. [PMID: 26406597 PMCID: PMC4634312 DOI: 10.1371/journal.pone.0138802] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 09/03/2015] [Indexed: 11/18/2022] Open
Abstract
The form of two hard tissues of the mammalian tooth, dentine and enamel, is the result of a combination of the phylogenetic inheritance of dental traits and the adaptive selection of these traits during evolution. Recent decades have been significant in unveiling developmental processes controlling tooth morphogenesis, dental variation and the origination of dental novelties. The enamel-dentine junction constitutes a precursor for the morphology of the outer enamel surface through growth of the enamel cap which may go along with the addition of original features. The relative contribution of these two tooth components to morphological variation and their respective response to natural selection is a major issue in paleoanthropology. This study will determine how much enamel morphology relies on the form of the enamel-dentine junction. The outer occlusal enamel surface and the enamel-dentine junction surface of 76 primate second upper molars are represented by polygonal meshes and investigated using tridimensional topometrical analysis. Quantitative criteria (elevation, inclination, orientation, curvature and occlusal patch count) are introduced to show that the enamel-dentine junction significantly constrains the topographical properties of the outer enamel surface. Our results show a significant correlation for elevation, orientation, inclination, curvature and occlusal complexity between the outer enamel surface and the enamel dentine junction for all studied primate taxa with the exception of four modern humans for curvature (p<0.05). Moreover, we show that, for all selected topometrical parameters apart from occlusal patch count, the recorded correlations significantly decrease along with enamel thickening in our sample. While preserving tooth integrity by providing resistance to wear and fractures, the variation of enamel thickness may modify the curvature present at the occlusal enamel surface in relation to enamel-dentine junction, potentially modifying dental functionalities such as blunt versus sharp dental tools. In terms of natural selection, there is a balance between increasing tooth resistance and maintaining efficient dental tools. In this sense the enamel cap acts as a functional buffer for the molar occlusal pattern. In primates, results suggest a primary emergence of dental novelties on the enamel-dentine junction and a secondary transposition of these novelties with no or minor modifications of dental functionalities by the enamel cap. Whereas enamel crenations have been reported by previous studies, our analysis do not support the presence of enamel tubercles without dentine relief nuclei. As is, the enamel cap is, at most, a secondary source of morphological novelty.
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Affiliation(s)
- Franck Guy
- CNRS INEE UMR 7262 – IPHEP, Institut de Paléoprimatologie et Paléontologie Humaine, Evolution et Paléoenvironnements. Université de Poitiers – Faculté des Sciences, Bât. B35 –TSA 51106, 6 rue Michel Brunet, 86073, Poitiers, Cedex 9, France
- * E-mail:
| | - Vincent Lazzari
- CNRS INEE UMR 7262 – IPHEP, Institut de Paléoprimatologie et Paléontologie Humaine, Evolution et Paléoenvironnements. Université de Poitiers – Faculté des Sciences, Bât. B35 –TSA 51106, 6 rue Michel Brunet, 86073, Poitiers, Cedex 9, France
| | - Emmanuel Gilissen
- Department of African Zoology, Royal Museum of Central Africa, B-3080, Tervuren, Belgium
- Laboratory of Histology and Neuropathology, Université Libre de Bruxelles, B-1070, Brussels, Belgium
| | - Ghislain Thiery
- CNRS INEE UMR 7262 – IPHEP, Institut de Paléoprimatologie et Paléontologie Humaine, Evolution et Paléoenvironnements. Université de Poitiers – Faculté des Sciences, Bât. B35 –TSA 51106, 6 rue Michel Brunet, 86073, Poitiers, Cedex 9, France
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28
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Bauer CC, Bons PD, Benazzi S, Harvati K. Using elliptical best fits to characterize dental shapes. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 159:342-7. [PMID: 26381860 DOI: 10.1002/ajpa.22866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 09/01/2015] [Accepted: 09/02/2015] [Indexed: 11/08/2022]
Abstract
A variety of geometric morphometric methods have recently been used to describe dental shape variation in human evolutionary studies. However, the applicability of these methods is limited when teeth are worn or are difficult to orient accurately. Here we show that elliptical best fits on outlines of dental tissues below the crown provide basic size- and orientation-free shape descriptors. Using the dm(2) and M(3) as examples, we demonstrate that these descriptors can be used for taxonomic purposes, such as distinguishing between Neanderthal and recent modern human teeth. We propose that this approach can be a useful alternative to existing methodology.
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Affiliation(s)
- Catherine C Bauer
- Paleoanthropology, Senckenberg Center for Human Evolution and Paleoecology, Eberhard Karls Universität Tübingen, Rümelinstrasse 23, Tübingen, 72070, Germany
| | - Paul D Bons
- Minerology and Geodynamics, Department of Geosciences, Eberhard Karls Universität Tübingen, Wilhelmstrasse 56, Tübingen, 72074, Germany
| | - Stefano Benazzi
- Department of Cultural Heritage, University of Bologna, via Degli Ariani 1, Ravenna, 48121, Italy.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig, D-04103, Germany
| | - Katerina Harvati
- Paleoanthropology, Senckenberg Center for Human Evolution and Paleoecology, Eberhard Karls Universität Tübingen, Rümelinstrasse 23, Tübingen, 72070, Germany
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Thepyou R, Chanmitkul W, Thanatvarakorn O, Hamba H, Chob-Isara W, Trairatvorakul C, Tagami J. Casein phosphopeptide-amorphous calcium phosphate and glass ionomer show distinct effects in the remineralization of proximal artificial caries lesion in situ. Dent Mater J 2015; 32:648-53. [PMID: 23903649 DOI: 10.4012/dmj.2012-253] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This study aimed to compare the ability of casein-phosphopeptide amorphous-calcium-phosphate (CPP-ACP) and glass-ionomer (GI) in remineralizing proximal artificial caries lesions (ACLs). Molar enamel-slabs were divided into: original-lesion control, intra-oral controls, and experimental (CPP-ACP or GI) groups. Specimens received ACLs and were bonded on subject maxillary first molars. After 4-weeks, mineral density (MD) was analyzed by μCT. Compared to control, CPP-ACP increased MD at 0-38/68-84 microns and the GI group had an increase at 0-68 microns, with a greater increase in MD compared to the CPP-ACP group from 0-53 microns. The mean percent remineralization (%R) showed differences between the GI, CPP-ACP groups and their paired controls. GI tended to increase remineralization more than CPP-ACP. In conclusion, CPP-ACP and GI demonstrated distinct remineralizing ability. GI induced greater remineralization in the superficial lesion, while CPP-ACP remineralized the lesion body. Their effects on percent remineralization and reducing lesion depth of proximal ACLs were similar.
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Affiliation(s)
- Rathapong Thepyou
- Faculty of Dentistry, Chulalongkorn University, 34 Henri-Dunant Rd, Patumwan, Bangkok 10330, Thailand
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Xing S, Martinón-Torres M, Bermúdez de Castro JM, Zhang Y, Fan X, Zheng L, Huang W, Liu W. Middle Pleistocene hominin teeth from Longtan Cave, Hexian, China. PLoS One 2014; 9:e114265. [PMID: 25551383 PMCID: PMC4281145 DOI: 10.1371/journal.pone.0114265] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2014] [Accepted: 11/04/2014] [Indexed: 11/24/2022] Open
Abstract
Excavations at the Longtan Cave, Hexian, Anhui Province of Eastern China, have yielded several hominin fossils including crania, mandibular fragments, and teeth currently dated to 412 ± 25 ka. While previous studies have focused on the cranial remains, there are no detailed analyses of the dental evidence. In this study, we provide metric and morphological descriptions and comparisons of ten teeth recovered from Hexian, including microcomputed tomography analyses. Our results indicate that the Hexian teeth are metrically and morphologically primitive and overlap with H. ergaster and East Asian Early and mid-Middle Pleistocene hominins in their large dimensions and occlusal complexities. However, the Hexian teeth differ from H. ergaster in features such as conspicuous vertical grooves on the labial/buccal surfaces of the central incisor and the upper premolar, the crown outline shapes of upper and lower molars and the numbers, shapes, and divergences of the roots. Despite their close geological ages, the Hexian teeth are also more primitive than Zhoukoudian specimens, and resemble Sangiran Early Pleistocene teeth. In addition, no typical Neanderthal features have been identified in the Hexian sample. Our study highlights the metrical and morphological primitive status of the Hexian sample in comparison to contemporaneous or even earlier populations of Asia. Based on this finding, we suggest that the primitive-derived gradients of the Asian hominins cannot be satisfactorily fitted along a chronological sequence, suggesting complex evolutionary scenarios with the coexistence and/or survival of different lineages in Eurasia. Hexian could represent the persistence in time of a H. erectus group that would have retained primitive features that were lost in other Asian populations such as Zhoukoudian or Panxian Dadong. Our study expands the metrical and morphological variations known for the East Asian hominins before the mid-Middle Pleistocene and warns about the possibility that the Asian hominin variability may have been taxonomically oversimplified.
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Affiliation(s)
- Song Xing
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | | | | | - Yingqi Zhang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | | | | | - Wanbo Huang
- Chongqing Three Gorges Institute of Paleoanthropology, China Three Gorges Museum, Chongqing, China
| | - Wu Liu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
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31
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Morita W, Yano W, Nagaoka T, Abe M, Ohshima H, Nakatsukasa M. Patterns of morphological variation in enamel-dentin junction and outer enamel surface of human molars. J Anat 2014; 224:669-80. [PMID: 24689536 PMCID: PMC4025894 DOI: 10.1111/joa.12180] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2014] [Indexed: 11/29/2022] Open
Abstract
Tooth crown patterning is governed by the growth and folding of the inner enamel epithelium (IEE) and the following enamel deposition forms outer enamel surface (OES). We hypothesized that overall dental crown shape and covariation structure are determined by processes that configurate shape at the enamel-dentine junction (EDJ), the developmental vestige of IEE. This this hypothesis was tested by comparing patterns of morphological variation between EDJ and OES in human permanent maxillary first molar (UM1) and deciduous second molar (um2). Using geometric morphometric methods, we described morphological variation and covariation between EDJ and OES, and evaluated the strength of two components of phenotypic variability, canalization and morphological integration, in addition to the relevant evolutionary flexibility, i.e. the ability to respond to selective pressure. The strength of covariation between EDJ and OES was greater in um2 than in UM1, and the way that multiple traits covary between EDJ and OES was different between these teeth. The variability analyses showed that EDJ had less shape variation and a higher level of morphological integration than OES, which indicated that canalization and morphological integration acted as developmental constraints. These tendencies were greater in UM1 than in um2. On the other hand, EDJ and OES had a comparable level of evolvability in these teeth. Amelogenesis could play a significant role in tooth shape and covariation structure, and its influence was not constant among teeth, which may be responsible for the differences in the rate and/or period of enamel formation.
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Affiliation(s)
- Wataru Morita
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto UniversityKyoto, Japan
| | - Wataru Yano
- Department of Oral Anatomy, Division of Oral Structure, Function and Development, Asahi University School of DentistryMizuho, Gifu, Japan
| | - Tomohito Nagaoka
- Department of Anatomy, St. Marianna University School of MedicineKawasaki, Kanagawa, Japan
| | - Mikiko Abe
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City UniversityOsaka, Japan
| | - Hayato Ohshima
- Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental SciencesNiigata, Japan
| | - Masato Nakatsukasa
- Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto UniversityKyoto, Japan
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Bailey SE, Benazzi S, Hublin JJ. Allometry, merism, and tooth shape of the upper deciduous M2 and permanent M1. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 154:104-14. [DOI: 10.1002/ajpa.22477] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 01/14/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Shara E. Bailey
- Department of Anthropology; Center for the Study of Human Origins, New York University; New York NY 10003
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig D-04103 Germany
| | - Stefano Benazzi
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig D-04103 Germany
| | - Jean-Jacques Hublin
- Department of Human Evolution; Max Planck Institute for Evolutionary Anthropology; Leipzig D-04103 Germany
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Benazzi S, Nguyen HN, Kullmer O, Hublin JJ. Unravelling the functional biomechanics of dental features and tooth wear. PLoS One 2013; 8:e69990. [PMID: 23894570 PMCID: PMC3720920 DOI: 10.1371/journal.pone.0069990] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 06/13/2013] [Indexed: 11/26/2022] Open
Abstract
Most of the morphological features recognized in hominin teeth, particularly the topography of the occlusal surface, are generally interpreted as an evolutionary functional adaptation for mechanical food processing. In this respect, we can also expect that the general architecture of a tooth reflects a response to withstand the high stresses produced during masticatory loadings. Here we use an engineering approach, finite element analysis (FEA), with an advanced loading concept derived from individual occlusal wear information to evaluate whether some dental traits usually found in hominin and extant great ape molars, such as the trigonid crest, the entoconid-hypoconulid crest and the protostylid have important biomechanical implications. For this purpose, FEA was applied to 3D digital models of three Gorillagorilla lower second molars (M2) differing in wear stages. Our results show that in unworn and slightly worn M2s tensile stresses concentrate in the grooves of the occlusal surface. In such condition, the trigonid and the entoconid-hypoconulid crests act to reinforce the crown locally against stresses produced along the mesiodistal groove. Similarly, the protostylid is shaped like a buttress to suffer the high tensile stresses concentrated in the deep buccal groove. These dental traits are less functional in the worn M2, because tensile stresses decrease physiologically in the crown with progressing wear due to the enlargement of antagonistic contact areas and changes in loading direction from oblique to nearly parallel direction to the dental axis. This suggests that the wear process might have a crucial influence in the evolution and structural adaptation of molars enabling to endure bite stresses and reduce tooth failure throughout the lifetime of an individual.
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Affiliation(s)
- Stefano Benazzi
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
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Carabelli’s trait revisited: An examination of mesiolingual features at the enamel–dentine junction and enamel surface of Pan and Homo sapiens upper molars. J Hum Evol 2012; 63:586-96. [DOI: 10.1016/j.jhevol.2012.06.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Revised: 03/24/2012] [Accepted: 05/08/2012] [Indexed: 11/23/2022]
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Smith TM, Olejniczak AJ, Zermeno JP, Tafforeau P, Skinner MM, Hoffmann A, Radovčić J, Toussaint M, Kruszynski R, Menter C, Moggi-Cecchi J, Glasmacher UA, Kullmer O, Schrenk F, Stringer C, Hublin JJ. Variation in enamel thickness within the genus Homo. J Hum Evol 2012; 62:395-411. [PMID: 22361504 DOI: 10.1016/j.jhevol.2011.12.004] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 11/08/2011] [Accepted: 12/13/2011] [Indexed: 10/28/2022]
Abstract
Recent humans and their fossil relatives are classified as having thick molar enamel, one of very few dental traits that distinguish hominins from living African apes. However, little is known about enamel thickness in the earliest members of the genus Homo, and recent studies of later Homo report considerable intra- and inter-specific variation. In order to assess taxonomic, geographic, and temporal trends in enamel thickness, we applied micro-computed tomographic imaging to 150 fossil Homo teeth spanning two million years. Early Homo postcanine teeth from Africa and Asia show highly variable average and relative enamel thickness (AET and RET) values. Three molars from South Africa exceed Homo AET and RET ranges, resembling the hyper thick Paranthropus condition. Most later Homo groups (archaic European and north African Homo, and fossil and recent Homo sapiens) possess absolutely and relatively thick enamel across the entire dentition. In contrast, Neanderthals show relatively thin enamel in their incisors, canines, premolars, and molars, although incisor AET values are similar to H. sapiens. Comparisons of recent and fossil H. sapiens reveal that dental size reduction has led to a disproportionate decrease in coronal dentine compared with enamel (although both are reduced), leading to relatively thicker enamel in recent humans. General characterizations of hominins as having 'thick enamel' thus oversimplify a surprisingly variable craniodental trait with limited taxonomic utility within a genus. Moreover, estimates of dental attrition rates employed in paleodemographic reconstruction may be biased when this variation is not considered. Additional research is necessary to reconstruct hominin dietary ecology since thick enamel is not a prerequisite for hard-object feeding, and it is present in most later Homo species despite advances in technology and food processing.
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Affiliation(s)
- Tanya M Smith
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
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36
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Prado-Simón L, Martinón-Torres M, Baca P, Olejniczak AJ, Gómez-Robles A, Lapresa M, Luis Arsuaga J, María Bermúdez de Castro J. Three-dimensional evaluation of root canal morphology in lower second premolars of early and middle pleistocene human populations from atapuerca (Burgos, Spain). AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2012; 147:452-61. [DOI: 10.1002/ajpa.22015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 12/14/2010] [Indexed: 11/11/2022]
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37
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Cooke SB. Paleodiet of extinct platyrrhines with emphasis on the Caribbean forms: three-dimensional geometric morphometrics of mandibular second molars. Anat Rec (Hoboken) 2011; 294:2073-91. [PMID: 22042688 DOI: 10.1002/ar.21502] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 09/16/2011] [Indexed: 11/10/2022]
Abstract
A three-dimensional geometric morphometric approach was employed to examine shape variation in laser-scan generated models of lower second molars and its relationship to diet in a sample of 9 extant and 16 extinct platyrrhine genera. Principal component analysis of twenty-three x,y,z landmarks describing the occlusal table and sidewalls showed that dental relief was the main contributing factor to variation along the first axis. Discriminant function analysis (DFA) of PC 1 scores and centroid size accurately classified extant platyrrhines according to dietary preference; however, without centroid size, the DFA was less successful. Within this framework, most of the fossil platyrrhines, including specimens from Patagonia, Colombia, Brazil, and the Caribbean, were predicted to have had a frugivorous diet, but several taxa were classified as having a frugivorous/insectivorous diet, the middle Miocene Neosaimiri, Patasola, and Laventiana, all from La Venta. Alouattins, including the La Ventan Stirtonia and the Cuban Paralouatta, showed variable classification as either frugivores or folivore/frugivores. Xenothrix, from Jamaica, was classified either as a frugivore or frugivore/omnivore. Dietary profiles across different extinct platyrrhine communities are compared and discussed in a paleoecological context.
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Affiliation(s)
- Siobhán B Cooke
- Department of Anthropology, New York Consortium on Evolutionary Anthropology, The Graduate Center, The City University of New York, USA.
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38
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Bailey SE, Skinner MM, Hublin JJ. What lies beneath? An evaluation of lower molar trigonid crest patterns based on both dentine and enamel expression. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2011; 145:505-18. [DOI: 10.1002/ajpa.21468] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 10/12/2010] [Indexed: 11/05/2022]
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Singleton M, Rosenberger AL, Robinson C, O'neill R. Allometric and metameric shape variation in Pan mandibular molars: a digital morphometric analysis. Anat Rec (Hoboken) 2010; 294:322-34. [PMID: 21235007 DOI: 10.1002/ar.21315] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Accepted: 08/19/2010] [Indexed: 11/06/2022]
Abstract
The predominance of molar teeth in fossil hominin assemblages makes the patterning of molar shape variation a topic of bioanthropological interest. Extant models are the principal basis for understanding dental variation in the fossil record. As the sister taxon to the hominin clade, Pan is one such model and the only widely accepted extant hominid model for both interspecific and intraspecific variation. To explore the contributions of allometric scaling and meristic variation to molar variation in Pan, we applied geometric shape analysis to 3D landmarks collected from virtual replicas of chimpanzee and bonobo mandibular molars. Multivariate statistical analysis and 3D visualization of metameric and allometric shape vectors were used to characterize shape differences and test the hypothesis that species of Pan share patterns of metameric variation and molar shape allometry. Procrustes-based shape variables were found to effectively characterize crown shape, sorting molars into species and tooth-row positions with ≥ 95% accuracy. Chimpanzees and bonobos share a common pattern of M(1) -M(2) metameric variation, which is defined by differences in the relative position of the metaconid, size of the hypoconulid, curvature of the buccal wall, and proportions of the basins and foveae. Allometric scaling of molar shape is homogeneous for M(1) and M(2) within species, but bonobo and chimpanzee allometric vectors are significantly different. Nevertheless, the common allometric shape trend explains most molar-shape differences between P. paniscus and P. troglodytes. When allometric effects are factored out, chimpanzee and bonobo molars are not morphometrically distinguishable. Implications for hominid taxonomy and dietary reconstruction are discussed.
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Affiliation(s)
- Michelle Singleton
- Department of Anatomy, Midwestern University, Downers Grove, Illinois 60515, USA.
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40
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Skinner MM, Gunz P. The presence of accessory cusps in chimpanzee lower molars is consistent with a patterning cascade model of development. J Anat 2010; 217:245-53. [PMID: 20629983 DOI: 10.1111/j.1469-7580.2010.01265.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Tooth crown morphology is of primary importance in fossil primate systematics and understanding the developmental basis of its variation facilitates phenotypic analyses of fossil teeth. Lower molars of species in the chimp/human clade (including fossil hominins) possess between four and seven cusps and this variability has been implicated in alpha taxonomy and phylogenetic systematics. What is known about the developmental basis of variation in cusp number - based primarily on experimental studies of rodent molars - suggests that cusps form under a morphodynamic, patterning cascade model involving the iterative formation of enamel knots. In this study we test whether variation in cusp 6 (C6) presence in common chimpanzee and bonobo lower molars (n = 55) is consistent with predictions derived from the patterning cascade model. Using microcomputed tomography we imaged the enamel-dentine junction of lower molars and used geometric morphometrics to examine shape variation in the molar crown correlated with variation in C6 presence (in particular the size and spacing of the dentine horns). Results indicate that C6 presence is consistent with predictions of a patterning cascade model, with larger molars exhibiting a higher frequency of C6 and with the location and size of later-forming cusps correlated with C6 variation. These results demonstrate that a patterning cascade model is appropriate for interpreting cusp variation in Pan and have implications for cusp nomenclature and the use of accessory cusp morphology in primate systematics.
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Affiliation(s)
- Matthew M Skinner
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
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41
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Colloquium paper: reconstructing human evolution: achievements, challenges, and opportunities. Proc Natl Acad Sci U S A 2010; 107 Suppl 2:8902-9. [PMID: 20445105 DOI: 10.1073/pnas.1001649107] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This contribution reviews the evidence that has resolved the branching structure of the higher primate part of the tree of life and the substantial body of fossil evidence for human evolution. It considers some of the problems faced by those who try to interpret the taxonomy and systematics of the human fossil record. How do you to tell an early human taxon from one in a closely related clade? How do you determine the number of taxa represented in the human clade? How can homoplasy be recognized and factored into attempts to recover phylogeny?
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Skinner MM, Evans A, Smith T, Jernvall J, Tafforeau P, Kupczik K, Olejniczak AJ, Rosas A, Radovčić J, Thackeray JF, Toussaint M, Hublin JJ. Brief communication: Contributions of enamel-dentine junction shape and enamel deposition to primate molar crown complexity. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2010; 142:157-63. [DOI: 10.1002/ajpa.21248] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Braga J, Thackeray JF, Subsol G, Kahn JL, Maret D, Treil J, Beck A. The enamel-dentine junction in the postcanine dentition of Australopithecus africanus: intra-individual metameric and antimeric variation. J Anat 2009; 216:62-79. [PMID: 19900182 DOI: 10.1111/j.1469-7580.2009.01154.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
We used micro-computed tomography and virtual tools to study metric and morphological features at the enamel-dentine junction and on the outer enamel surface in the postcanine dentition of an exceptionally well-preserved maxilla and mandible of an early hominin. The fossil, Sts 52 from Sterkfontein, South Africa, is attributed to Australopithecus africanus and is about 2.5 million years old. For comparative purposes in this exploratory study, we also used micro-computed tomography to analyse the dentition of a common chimpanzee (Pan troglodytes), a pygmy chimpanzee (Pan paniscus) and three extant humans. Metameric variation of the 3D enamel-dentine junction in the two chimpanzee mandibles was much smaller than in extant humans. Variation in metameric shape was high and complex. Notably, the mandibular metameric variation in extant humans can be greater within individuals, as compared with variation between individuals, with differences in shape appearing greater for M2 compared with M1. We recommend the use of a new approach in which individual metameric variation is systematically assessed before making inferences about differences between fossil hominin species. The fossil hominin examined in this study showed a metameric pattern of mandibular variation in shape that was comparable to the pattern seen in two chimpanzees. This degree of metameric variation appeared relatively small compared with the much larger patterns of variation observed within and between extant humans.
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Affiliation(s)
- J Braga
- Laboratoire d'Anthropobiologie, Université de Toulouse, France.
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44
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Skinner MM, Gunz P, Wood BA, Boesch C, Hublin JJ. Discrimination of extantPanspecies and subspecies using the enamel-dentine junction morphology of lower molars. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2009; 140:234-43. [PMID: 19382140 DOI: 10.1002/ajpa.21057] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Matthew M Skinner
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig 04103, Germany.
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