Dental remains of the Middle Pleistocene hominins from the Sima de los Huesos site (Sierra de Atapuerca, Spain): Mandibular dentition

Abstract

The Middle Pleistocene site of the Sima de los Huesos (Sierra de Atapuerca, northern Spain) has yielded a considerable number of human fossils during the period 1984–2020. Among them, up to 314 mandibular teeth have been identified. In this second paper dedicated to the dentition we present the description of the eight dental classes of the mandible following the Arizona State University Dental Anthropology System (ASUDAS) classification. In addition, we show the mean mesiodistal and buccolingual diameters obtained in these teeth compared to those of Neanderthals and a modern human sample. The morphology of both the anterior and posterior teeth suggests a close relationship of the Sima de los Huesos hominins with the populations of the second half of the Middle Pleistocene of Europe and the Near East, as well as with the so‐called classic Neanderthals of Europe. The combination of dental traits in these populations is characteristic and diagnostic and suggests grouping the Sima de los Huesos hominins with the other paleodemes in a Neanderthal clade. The dental evidence of the Sima de los Huesos hominins is key to propose a complex model for the settlement of Europe during the Middle Pleistocene. In this period, different migrations of human groups probably coming from Southwest Asia, replacements, prolonged isolations, as well as hybridization and introgression processes would have contributed to the diversity of hominins in Europe.

A human lower third molar from the Acheulean site of Cueva del Ángel (Lucena, Córdoba, Spain)

“…Taurodontism is not frequent among modern humans (<10%) and it is recorded with the lowest degrees of expression (Constant & Grine, 2001; Einy et al, 2022; Klein et al, 2017). Although some pre‐Neanderthals exhibit different grades of taurodontism (Bermúdez de Castro et al, 2021; Martínez de Pinillos et al, 2020), it is among Neanderthals where this trait is significantly more frequent, especially within the Krapina sample with a frequency of 63% for M 3 , but it is not ubiquitous and the degrees of expression are variable (Kupczik & Hublin, 2010).…”

“…Actually, those traits in which CA‐2019‐E2‐2 differs from contemporary early Neanderthals are frequent within the MP population from SH. The absence of the hypoconulid in M 3 is not uncommon among SH hominins (Bermúdez de Castro et al, 2021; Bermúdez de Castro & Nicolás, 1995; Martinón‐Torres et al, 2012). Furthermore, the small crown dimensions of CA‐2019‐E2‐2 align with the significant M 3 reduction observed in SH hominins, which is consistent with the absence of the hypoconulid and the decrease of the talonid area (Bermúdez de Castro, 1986; Bermúdez de Castro & Nicolás, 1995; Gómez‐Robles et al, 2015).…”

How the Sima de los Huesos was won

“…This success opened the door to carrying out the test with some very fragmentary human remains and in 2014 it was possible to obtain and sequence mitochondrial DNA Its comparison with the other fossil humans for which the genomes were known (the Neanderthals and the Denisovans) yielded a surprising result. Anatomically, the fossils from Sima de los Huesos and Neanderthals show a clear phylogenetic affinity, especially in the morphology of the jaw (Quam et al, 2024) and dentition (Bermúdez de Castro et al, 2024a, 2024b), greater than that between Neanderthals and Denisovans, but, however, the mitochondrial DNA of the fossils from Sima de los Huesos presented greater resemblance with the Denisovans than with the Neanderthals (Meyer et al, 2014). This discrepancy between anatomical and genetic data allowed for several explanations, but to solve the problem it was necessary to obtain significant nuclear DNA sequences, something that was technically more difficult than obtaining mitochondrial DNA.…”

Evaluating the patterning cascade model of tooth morphogenesis in the human lower mixed and permanent dentition

“…Dental anthropological analyses often utilize nonmetric crown traits to assess the degree of similarity among global populations [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], detect biological kinship within a site [18][19][20][21][22][23][24][25][26][27][28][29], establish phylogenetic relationships across taxa [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49], explore the population history associated with specific groups or geographic regions , and more recently, to...…”