Dental remains of Late Pleistocene European foragers: external and internal characterization
Résumé
Teeth provide a wealth of unique information about taxonomy, phylogeny, and development that are mainly stored within tooth tissues. While variability of internal tooth structure (in particular, enamel thickness) within the genus Homo has been considered at a macroevolutionary scale, microevolutionary tendencies in Homo sapiens across the Late Pleistocene are still unreported. At the external level, a reduction of crown dimensions and a morphological simplification have been recorded throughout the Upper Paleolithic. The aim of this study is to use a high-resolution microCT record to explore how the external structural reduction is expressed in internal dental tissues for humans between ca. 20000 to 10000 cal BP. The sample is composed of 210 teeth of individuals (MNI=20) dated from Middle Magdalenian, Upper Magdalenian and Azilian French sites, from which 40 deciduous and permanent teeth have been microscanned. External assessment (crown dimensions, nonmetric variations) has been combined with internal structure analysis (enamel thickness, dental tissue proportions) using 3D imaging methods, in order to characterize the dental variability from a whole crown perspective. While a decrease in crown size has been confirmed, results from the internal tooth analyses show different patterns for enamel and dentine components between deciduous and permanent teeth, upper and lower ones, as well as between anterior and posterior dentition. In particular, the deciduous teeth that are more conservative shows that major differences occurred between specimens dated from the Upper Magdalenian and the Azilian periods. Thus, the evolutionary tendencies are more complex when we considered the internal tooth structure.