The Neanderthal mandible BD 1 from La Chaise-de-Vouthon Abri Bourgeois-Delaunay (Charente, Southwestern France, OIS 5e). Dental tissue proportions, cortical bone distribution and endostructural asymmetry

Abstract

The 23 fossil human remains found at La Chaise-de-Vouthon Abri Bourgeois-Delaunay (Charente, Southwestern France) are all attributed to Neanderthals. The BD 1 mandible represents one of the best preserved specimens recovered in this assemblage, still bearing the entire set of 16 teeth, and attributed to an adult - likely 20-35 years old –individual. The geochronological and paleontological data indicate that the Neanderthals from Abri Bourgeois-Delaunay lived in a temperate environment between 127 and 116 ka (i.e., during the OIS 5e). In this study, we integrate and expand the morphometric record of BD 1 by quantifying the tissue proportions of its entire permanent dentition, including radicular thickness repartition of four front teeth, and comparing its degree of endostructural asymmetry in tooth tissue organization and postcanine cortical bone topography with the patterns shown by Regourdou 1. Our results show that crown and radicular dental internal signature is typically Neanderthal, comparable with the available data for Regourdou 1, and is unambiguously distinct from the fossil and extant modern human patterns. Asymmetry in tooth tissue proportions in BD 1 and Regourdou 1 is clearly non-directional, as side dominance is nearly equally distributed between the left and the right antimeres. Similarly, both Neanderthal mandibles show no marked cortical bone asymmetry at the molar level, even if a slight right dominance is found in BD 1. Even if these results are globally consistent for the two Neanderthal mandible, extensive methodological research on the patterns of age- and sex-related endostructural variation displayed by human population samples from diverse chrono-geographic, socio-economic and biocultural contexts is still needed to more confidently evaluate the evolutionary and adaptive significance of the signals from the fossil record.