Caracterización de los tejidos dentales caninos permanentes de las poblaciones actuales y del Pleistoceno de la sierra de Atapuerca (Burgos) mediante microtomografía microcomputarizada (micro-CT): dimorfismo sexual y otras inferencias paleobiológicas

Abstract

The assessment of the dental tissue proportions in the human dentition with a focus in the analysis of differences between males and females has triggered a special interest within forensic sciences. At the same time, the evaluation of the enamel and dentin dimensions has become a routine in taxonomic studies in human evolution. In this PhD dissertation, we employed microtomographic image analysis techniques to assess the three-dimensional dental tissue proportions of the permanent canines belonging to the Pleistocene populations of the Sierra de Atapuerca (Spain), as well as the canines of a large sample of modern humans of known sex. The main objective of this study is to explore the variability present in the dimensions of the different dental tissues of the populations under study and its utility to assess sexual dimorphism. Our study reveals that the dentin-pulp complex of permanent canines in modern humans is absolutely and relatively larger in males, resulting in a relatively thicker enamel in females.. This histological pattern has allowed us to define several variables that were used in the development of a new methodology for sex estimation. The accuracy rates obtained using this methodology reach values of up to 92.3% in modern humans, a reliability comparable to that of other methods commonly applied to the skull or pelvis. On the other hand, the study of the dental tissue proportions of the permanent canines of the Early and Middle Pleistocene hominins from the Atapuerca sites has helped us to improve our understanding about the polarity of the thin enamel described as typical of H. neanderthalensis dentition, as well as to assess the evolution of this trait in the Pleistocene populations of Europe. In particular, the similarities observed in the dental tissue proportions of the the Sima de los Huesos (SH) and the Krapina canines indicate that the thinly enameled pattern cannot be considered as a feature only present in the classic Neandertals but a trait shared by all members of the Neandertal lineage. Fur-ABSTRACT 3 ESTRUCTURA DE LA TESIS DOCTORAL 9

Similarities and differences in the dental tissue proportions of the deciduous and permanent canines of Early and Middle Pleistocene human populations

“…These authors could appreciate that the relative enamel thickness (3DRET) of canines belonging to Gran Dolina and Sima de los Huesos dental samples concur with the thinly enameled pattern observed in the Neanderthals (García-Campos et al, 2019). These results differ from those obtained by the same authors on the study of the posterior dentition from these Sierra de Atapuerca populations (Martín-Francés et al, 2018, 2020.…”

“…This work also comprises a recent modern humans sample (RMH) composed of 51 permanent and 72 deciduous dental canines belonging to individuals of European origin. This material comes from the anthropological collection of the Escuela de Medicina Legal de Madrid (Spain) (see García Campos, 2020; García‐Campos et al, 2018a, 2018b, 2019, 2020) and the Ratón Pérez Collection stored at the Centro Nacional de Investigación sobre la Evolución Humana (see Martínez de Pinillos et al, 2021). A total of 101 individuals are represented in our study sample.…”

“…Different studies have described how changes in concentrations of steroid hormones influence the dimensions of the dentin component of permanent canines (Zilberman & Smith, 2001). So much so that the proportions in which different dental tissues are present in permanent canines have been successfully used for sex estimation, not only in modern humans but also in fossil samples (García-Campos et al, 2018a, 2018b, 2020.…”

“…This work also comprises a recent modern humans sample (RMH) composed of 51 permanent and 72 deciduous dental canines belonging to individuals of European origin. This material comes from the anthropological collection of the Escuela de Medicina Legal de Madrid (Spain) (see García Campos, 2020;García-Campos et al, 2018a, 2018b, 2019, 2020 In some cases, a maxillary and a mandible canine from the same individual were measured, although only one antimere per individual was taken into consideration. We discarded pieces with pathological damage that could affect the mineralized tissues.…”

“…As for evaluating the three-dimensional (3D) tissue proportions, we measured the variables and indices described by Olejniczak et al (2008a, b). Before that, we isolated the crown from the root in each dental piece, considering the cervical line as the fundamental morphological feature to establish the lower limit between both structures (see García-Campos et al, 2018a, 2018b, 2019, 2020, and Figure 1e). We quantified the 3D variables described in detail in Table S2 and in Figure 1f.…”