Variation in enamel thickness within the genus Homo |
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Authors: | Smith Tanya M Olejniczak Anthony J Zermeno John P Tafforeau Paul Skinner Matthew M Hoffmann Almut Radovčić Jakov Toussaint Michel Kruszynski Robert Menter Colin Moggi-Cecchi Jacopo Glasmacher Ulrich A Kullmer Ottmar Schrenk Friedemann Stringer Chris Hublin Jean-Jacques |
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Institution: | a Department of Human Evolutionary Biology, 11 Divinity Avenue, Harvard University, Cambridge, MA 02138, USA b Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany c European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, BP 220, 38043 Grenoble Cedex, France d Museum für Vor- und Frühgeschichte, Schloss Charlottenburg - Langhansbau, Spandauer Damm 22, D-14059 Berlin, Germany e Croatian Natural History Museum, Demetrova 1, 10000 Zagreb, Croatia f Direction de l’Archéologie, Service Public de Wallonie, 5100 Namur, Belgium g Department of Palaeontology, The Natural History Museum, London SW7 5BD, United Kingdom h Department of Anthropology and Development Studies, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa i Dipartimento di Biologia Evoluzionistica ‘Leo Pardi,’ Università di Firenze, via del Proconsolo, 12, 50122 Firenze, Italy j Institute of Earth Sciences, Ruprecht Karl University Heidelberg, D-69120 Heidelberg, Germany k Department of Paleoanthropology and Messel Research, Senckenberg Research Institute, D-60325 Frankfurt, Germany l Department of Vertebrate Paleontology, Institute for Ecology, Evolution, and Diversity, Johann Wolfgang Goethe University, Frankfurt, Germany |
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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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Keywords: | Human evolution Hominin tooth structure Dental morphology Early Homo Archaic Homo Neanderthal |
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