JASs Reports Journal of Anthropological Sciences the JASs is published by the Istituto Italiano di Antropologia www.isita-org.com Vol. 88 (2010), pp. 129-150 The association between dental mineralization and mandibular form: a study combining additive conjoint measurement and geometric morphometrics Michael Coquerelle 1,2 , Priscilla Bayle 3,4 , Fred L. Bookstein 1,5 , José Braga 2 , Demetrios J. Halazonetis 6 , Stanislav Katina 1,7 & Gerhard W. Weber 1 1) Department of Anthropology, University of Vienna, 1090 Vienna, Austria e-mail: michael.coquerelle@univie.ac.at 2) Anthropologie Moléculaire et Imagerie de Synthèse, FRE 2960, Université Paul Sabatier, 31000 Toulouse, France 3) Research Department of Cell and Developmental Biology, UCL, London WC1E 6BT, UK 4) Département de Préhistoire, UMR 7194-USM 204, Muséum National d’Histoire Naturelle, 75013 Paris, France 5) Department of Statistics, University of Washington, Seattle, Washington 98195, U.S.A. 6) Orthodontic Department, University of Athens Dental School, 11527 Athens, Greece 7) Department of Applied Mathematics and Statistics, Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynska dolina, 842 48 Bratislava, Slovakia Summary - Studies have suggested that dental development substantially infuences the variation of mandibular morphology and growth in primates. As a contribution to the methodology of such studies, we introduce a novel approach to quantifying the covariation between teeth and mandible. Tis was done showing fuctuations in the magnitude of this covariation within a sample of modern human mandibles at di ferent postnatal ages. Dense CT- derived mandibular surface meshes of 73 females and 71 males, ranging in age from birth to adulthood, were processed by methods of geometric morphometrics. Each specimen’s deciduous and permanent teeth were rated for mineralization stage. Form-space principal component analysis of the morphometric data was used to produce a single metric variable that best explains mandibular-form variation. Tis variable was then used to quantify the developing teeth, all together, through the use of the additive conjoint measurement method. Tis new metric variable corresponds to the dental prediction of the mandibular-form variation. Finally, we examine the covariation of the two over the full range of mineralization stages. We found a strikingly tight association between mandibular form and dental maturation up through the full emergence of the deciduous dentition (about age 2 y.), followed by an equally striking decline in that association in later developmental stages, particularly for girls. Te onset of the decline of the teeth-mandible relationship coincides with the onset time of the adult-like pattern of mastication and speech. Te increasingly functional diversity may lead to more independence between dental development and mandibular growth than during the frst two years. Keywords - Dentition, Mandible, Modern humans, Growth, Covariation Introduction Among extant primates, the great apes have a prognathic face with large jaws and teeth adapted for powerful mastication, whereas in humans, the face is orthognathic, the dental arcade reduced and the correspondingly smaller jaw is commit- ted to two functions, mastication and speech.