Dental remains from the Sima de los Huesos

Abstract

To date, the Sima de los Huesos dental simple consists of more than 530 permanent teeth including all dental classes and assigned to a minimum number of 28 individuals. This sample has been characterized with classic morphometrics, geometric morphometrics and also recently, by means of microtomography. These studies are consistent in the identification of strong Neanderthal affinities. The SH dental remains present all the features that either in their degree of expression, frequency and/or pattern of combination have been considered typical of H. neanderthalensis. However, the SH dentitions do not fit in a progressive “neanderthalization” sequence as they are i) more derived than some contemporaneous populations such as Arago and Mauer and ii) “more Neanderthal than some Neanderthals” themselves, by falling in the extreme of the gradient of the Neanderthal variation for some features. In addition, the SH dentitions present some unusual features for a Middle Pleistocene population such as posterior teeth that are smaller in absolute terms than those of other Pleistocene groups, and are comparable to modern humans not only in size but in other traits such as similar intermolar size ratios, frequent absence of hypoconulid and hypocone and pattern of cusp proportions in upper first molars. This line of evidence is not in favor of a gradual or anagenetic process for the evolution of the European Middle Pleistocene groups. Here, we reevaluate the taxonomic and phylogenetic position of the SH population and question its allocation into a taxon (H. heidelbergensis) that has Mauer as its holotype.