Dental developmental pattern and tooth internal structure in the Neanderthal child Châteauneuf 2 (Hauteroche, Charente, France)
Résumé
Differences have been reported between Neanderthals and recent humans in their pattern of dental development and internal tooth structure. Compared to recent humans, Neanderthals show an early development of the molars relative to that of the incisors and first premolars, larger tooth volume at each position but with a mesio-distal decrease along the arcade, similar enamel but larger dentine volumes in their deciduous and permanent teeth. However, few complete dentitions have been published for their tissue proportions, and little quantitative information is available on anterior teeth. Furthermore, how dental maturational patterns and metameric variation in tissue proportions along the arcade are linked together has been poorly investigated. Here we used microCT-based data, as well as radiographic and CT records, to finely quantify these variables in the deciduous and permanent teeth of the Neanderthal child Châteauneuf 2 from Hauteroche (Charente, France), and compare the measures to other Neanderthals and to Late Pleistocene and Holocene modern humans of worldwide origins. Like other Neanderthals and the Gravettian child from Lagar Velho, Châteauneuf 2 shows an advancement of its first molar development compared to later Pleistocene and Holocene individuals. While the Châteauneuf 2 internal tooth structure is in line with the Neanderthal range of variation for deciduous teeth, it extends the range of variation known hitherto for the first permanent molar. Furthermore, Châteauneuf 2 fits the Neanderthal pattern by having particularly large incisor dentine volumes and high metameric variation. Our results suggest that Neanderthal intra- and inter-population variation in internal dental structure is still far from having been fully documented. Even if future investigations are needed to unlock the genetically- and/or functionally-related factors sustaining these observations, the relative anterior versus posterior developmental stages in Neanderthals may result from volumetric and tissue proportional differences between anterior and posterior teeth compared to those of recent humans.