An early enamel thickness decrease in the permanent canines of the European populations of Atapuerca

An early enamel thickness decrease in the permanent canines of the European populations of Atapuerca
Journal 8th Annual ESHE Meeting
Authors García-Campos, Cecilia; Martinón-Torres, María; Martín-Francés, Laura; Modesto-Mata, Mario; Martínez de Pinillos, Marina; Arsuaga, Juan Luis; Bermúdez de Castro, José María
Volume PESHE 7
Year 2018
DOI 10.13140/RG.2.2.35475.53284
Dental traits are considered to be highly heritable, selectively neutral and evolutionary conservative, representing a useful tool in taxonomic and phylogenetic studies. Dental tissue proportions, in general, and the enamel thickness, in particular, have been of considerable interest over the past century. Despite all research work carried out on posterior dentition, the variation in dental tissue proportions within the genus Homo, and specifically the origin of the two enamel thickness tendencies that appeared in Neanderthals and modern humans during Middle Pleistocene is poorly understood. This is mainly due to the absolute scarcity of data on early European populations. In this context, large tooth samples of well-defined populations, such as those of the archaeological complex collections from Sierra de Atapuerca in Spain, could contribute to fill this gap. This study aims to discuss the meaning of the possible similarities and differences in the dental tissue proportions between Gran Dolina (n=3) and Sima de los Huesos (n=32) samples, the Neanderthal dental remains of Krapina (Croatia) (n=18) as well as between a recent modern human sample from Europe and Africa (n=126). To do so, microtomographic imaging analytical techniques were applied to a sample of permanent canine teeth belonging to these populations, as well as the enamel and dentine volumes and surfaces were measured. Finally, the mean values of each measurement were compared among taxa. Our results show that Early and Middle Pleistocene populations from Atapuerca exhibit large coronal and root dimensions in their permanent canines, as well as a thinly enamelled pattern, which has been traditionally considered an autapomorphic Neanderthal trait. Therefore, these results might support an early enamel thickness decrease, which is already observed 800 kyr ago in Homo antecessor and maintained in later groups such as Sima de los Huesos and Neanderthal populations during the Middle Pleistocene. This tissue pattern seems to be the result of the dentine-pulp complex expansion and the increase in the complexity of the EDJ surface in these taxa´s canines. Likewise, a greater role of the coronal dentine component seems to be accompanied by larger roots, might be related with more bone robustness. Future studies on dental tissue proportion of the posterior teeth belonging to Sima de los Huesos and Gran Dolina individuals could help to increase the amount of information available on the taxonomical distinctive patterns of these populations.

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