Le Luyer Mona, Coquerelle Michael, Rottier Stéphane, Bayle Priscilla
Unité Mixte de Recherche 5199, de la Préhistoire à l'Actuel: Culture, Environnement, Anthropologie (UMR 5199 PACEA), Université de Bordeaux, Pessac, France.
Department of Oral Surgery, Rey Juan Carlos University, Alcorcon, Spain.
PLoS One. 2016 Jul 22;11(7):e0159688. doi: 10.1371/journal.pone.0159688. eCollection 2016.
Variations in the dental crown form are widely studied to interpret evolutionary changes in primates as well as to assess affinities among human archeological populations. Compared to external metrics of dental crown size and shape, variables including the internal structures such as enamel thickness, tissue proportions, and the three-dimensional shape of enamel-dentin junction (EDJ), have been described as powerful measurements to study taxonomy, phylogenetic relationships, dietary, and/or developmental patterns. In addition to providing good estimate of phenotypic distances within/across archeological samples, these internal tooth variables may help to understand phylogenetic, functional, and developmental underlying causes of variation. In this study, a high resolution microtomographic-based record of upper permanent second molars from 20 Neolithic individuals of the necropolis of Gurgy (France) was applied to evaluate the intrasite phenotypic variation in crown tissue proportions, thickness and distribution of enamel, and EDJ shape. The study aims to compare interindividual dental variations with burial practices and chronocultural parameters, and suggest underlying causes of these dental variations. From the non-invasive characterization of internal tooth structure, differences have been found between individuals buried in pits with alcove and those buried in pits with container and pits with wattling. Additionally, individuals from early and recent phases of the necropolis have been distinguished from those of the principal phase from their crown tissue proportions and EDJ shape. The results suggest that the internal tooth structure may be a reliable proxy to track groups sharing similar chronocultural and burial practices. In particular, from the EDJ shape analysis, individuals buried in an alcove shared a reduction of the distolingual dentin horn tip (corresponding to the hypocone). Environmental, developmental and/or functional underlying causes might be suggested for the origin of phenotypic differences shared by these individuals buried in alcoves.
人们广泛研究牙冠形态的变异，以解读灵长类动物的进化变化，以及评估人类考古群体之间的亲缘关系。与牙冠大小和形状的外部指标相比，包括牙釉质厚度、组织比例以及牙釉质 - 牙本质交界处（EDJ）的三维形状等内部结构变量，已被描述为研究分类学、系统发育关系、饮食和/或发育模式的有力指标。除了能很好地估计考古样本内部/之间的表型距离外，这些牙齿内部变量可能有助于理解变异的系统发育、功能和发育的潜在原因。在本研究中，应用基于高分辨率显微断层扫描技术对来自法国古尔吉墓地20名新石器时代个体的上颌第二恒磨牙进行记录，以评估牙冠组织比例、牙釉质厚度和分布以及EDJ形状的遗址内表型变异。该研究旨在比较个体间的牙齿变异与埋葬方式和年代文化参数，并提出这些牙齿变异的潜在原因。通过对牙齿内部结构的非侵入性表征，发现埋葬在有壁龛的坑中的个体与埋葬在有容器的坑和有编条的坑中的个体之间存在差异。此外，墓地早期和近期阶段的个体在牙冠组织比例和EDJ形状方面与主要阶段的个体有所不同。结果表明，牙齿内部结构可能是追踪具有相似年代文化和埋葬方式群体的可靠指标。特别是，通过EDJ形状分析，埋葬在壁龛中的个体共享远舌侧牙本质角尖（对应于次尖）的减小。对于埋葬在壁龛中的这些个体所共有的表型差异的起源，可能暗示环境、发育和/或功能方面的潜在原因。
