On the dental variability of the Early and Middle Pleistocene populations of Atapuerca

Abstract

As the variation in dental form is highly heritable, teeth are more useful than other skeletal remains to assess resemblances between extant and extinct human populations, and to investigate phylogenetic relationships and the scenario in which these species evolved. The extraordinary human fossils found in different archaeological sites of Sierra de Atapuerca (Burgos, Spain), such as Gran Dolina-TD6 and Sima de los Huesos, give us the opportunity to explore the inter and intra-populational variability of the Early and Middle Pleistocene dental collections from Atapuerca. Up to date, the Gran Dolina-TD6 site has yielded a minimum number of individuals (MNI) of 11 whereas Sima de los Huesos (SH) has provided the largest hominin collection worldwide coming from one site with a MNI of 28. Due to this exceptional dental sample of SH, we have the possibility of not only performing comparisons between groups, but also assess the variability within one population. By studying the Atapuerca samples as well as other comparative groups such as Homo neanderthalensis and Homo sapiens, we aim to investigate the Trigonid Crest pattern in these populations in order to make some possible evolutionary inferences. This morphological feature has been classically studied at the enamel, but now we are able to reconstruct tridimensionally the inner surfaces by means of non-destructive techniques such as the microtomography (mCT). Our results reveal a higher variability in the expression of trigonid crests at the dentine compared to the enamel but, despite this variability, in almost all cases there is large general correlation between the expressions of crests at both surfaces. Besides, the analysis reveals that the SH sample matches broadly the trigonid crest patterns displayed by Homo neanderthalensis and differs from those exhibited by Homo antecessor and Homo sapiens. Other aspects of the variability of the trigonid crest expression at the dentine are presented and discussed.