Neanderthal teeth from moula-guercy, Ardèche, France

Neanderthal child's maxilla from Baume Moula-Guercy (Soyons, Ardèche, France)

This article provides an ontogenetically-based comparative description of the Guercy 3 partial child's maxilla with Rdm2 -RM1 and unerupted RI2 -RP4 from Baume Moula-Guercy (MIS 5e) and examines its affinities to European and Middle Eastern Middle-to-Late Pleistocene (≈MIS 14-MIS 1) Homo. Description of the Guercy 3 maxilla and dentition (7.0 year ± 0.9 month) is based on observations of original fossils, casts, CT scans, literature descriptions, and virtual reconstructions. Our ontogenetic sample comprises a Preneanderthal-Neanderthal group and a Homo sapiens group. These groups are subdivided into (1) Preneanderthals (≈MIS 14-9), Early Neanderthals (MIS 7-5e), and Late Neanderthals (MIS 5d-3), and (2) Middle (MIS 5), Upper (MIS 3-2), and Late Upper Paleolithic (≈MIS 1), and recent H. sapiens. Standard techniques were employed for measurements and developmental age determinations.The Guercy 3 maxilla lacks changes found in Late Neanderthals, including the positioning of the root of the zygomatic process, infraorbital and nasal plates, premaxilla, buccal and labial alveolus, maxillary sinus, nasal cavity, and verticality of anterior tooth implantation. The morphology of the Guercy 3 maxilla more closely approximates that of Sima de los Huesos Preneanderthals, while the dentition more closely approximates the Early-Late Neanderthal condition. Maxillary remains of children and juveniles between MIS 14-MIS 5e are rare, and the available sample is fragmentary and distorted. Although fragmentary, the Guercy 3 maxilla is undistorted and provides new insights into the evolution of the midface in Neanderthals.

Behavioral strategies of prehistoric and historic children from dental microwear texture analysis

Introduction

Reconstructing the dietary and behavioral strategies of our hominin ancestors is crucial to understanding their evolution, adaptation, and overall way of life. Teeth in general, and dental microwear specifically, provide a means to examine these strategies, with posterior teeth well positioned to tell us about diet, and anterior teeth helping us examine non-dietary tooth-use behaviors. Past research predominantly focused on strategies of adult individuals, leaving us to wonder the role children may have played in the community at large. Here we begin to address this by analyzing prehistoric and historic children through dental microwear texture analysis of deciduous anterior teeth.

Materials and Methods

Four sample groups were used: Neandertals (N = 8), early modern humans (N = 14), historic Egyptians from Amarna (N = 19) and historic high-Arctic Inuit from Point Hope, Alaska (N = 6). Anterior deciduous teeth were carefully cleaned, molded, and cast with high-resolution materials. Labial surfaces were scanned for dental microwear textures using two white-light confocal microscopes at the University of Arkansas, and a soft filter applied to facilitate data comparisons.

Results and Discussion

Results show that dental microwear texture analysis successfully differentiated the samples by all texture variables examined (anisotropy, complexity, scale of maximum complexity, and two variants of heterogeneity). Interestingly, the Neandertal and Point Hope children had similar mean values across all the texture variables, and both groups were significantly different from the Amarna, Egyptian children. These differences suggest diversity in abrasive load exposure and participation in non-dietary anterior tooth-use behaviors. Further analyses and an expanded sample size will help to strengthen the data presented here, but our results show that some prehistoric and historic children took part in similar behaviors as their adult counterparts.

Neanderthal cranial remains from Baume Moula-Guercy (Soyons, Ardèche, France)

OBJECTIVES

We provide the first comparative description of the Guercy 1 cranium and isolated cranial fragments from Baume Moula-Guercy and examine their affinities to European Preneanderthals, Neanderthals, and Homo sapiens.

MATERIALS AND METHODS

The Moula-Guercy hominins derive from deposits chronostratigraphically and biostratigraphically dated to the Eemian Interglacial (MIS 5e). For comparisons we compiled a sample of European and Southwest Asian subadult-adult Middle-to-Late Pleistocene hominins (≈MIS 14-MIS 2; N = 184). This sample represents a Preneanderthal-Neanderthal group and a H. sapiens group, both of which were further divided into three time-successive subgroups defined by associated marine isotope stages (MIS). Metric and morphological observations were made on the original fossils and a virtual reconstruction of Guercy 1. Developmental age and sex and the minimum-maximum number of individuals were assessed.

RESULTS

Guercy 1 represents the remains of a late stage adolescent (≈15-16.0 years) female. Morphological and metric data combine to associate the total morphological pattern expressed in Guercy 1 with our MIS 7-MIS 5e ("Early Neanderthal") subgroup. Some features, especially those related to the frontal, suggest linkage to a paleodeme comprising the Moula-Guercy, Artenac, La Chaise Abri Suard and, possibly, the Biache-Saint-Vaast samples.

DISCUSSION

Remains of MIS 7-MIS 5e Neanderthals are rare and fragmentary, especially those dated to the Last Interglacial. The Baume Moula-Guercy sample provides new insights into the total morphological pattern expressed in MIS 5e Neanderthals. Further, our results support earlier suggestions that MIS 7-MIS 5e European hominins represent a morphotype that is distinct from both earlier and later members of the Preneanderthal-Neanderthal group.

Short and long period growth markers of enamel formation distinguish European Pleistocene hominins

Characterizing dental development in fossil hominins is important for distinguishing between them and for establishing where and when the slow overall growth and development of modern humans appeared. Dental development of australopiths and early Homo was faster than modern humans. The Atapuerca fossils (Spain) fill a barely known gap in human evolution, spanning ~1.2 to ~0.4 million years (Ma), during which H. sapiens and Neandertal dental growth characteristics may have developed. We report here perikymata counts, perikymata distributions and periodicities of all teeth belonging to the TE9 level of Sima del Elefante, level TD6.2 of Gran Dolina (H. antecessor) and Sima de los Huesos. We found some components of dental growth in the Atapuerca fossils resembled more recent H. sapiens. Mosaic evolution of perikymata counts and distribution generate three distinct clusters: H. antecessor, Sima de los Huesos and H. sapiens.

Anterior tooth-use behaviors among early modern humans and Neandertals

Early modern humans (EMH) are often touted as behaviorally advanced to Neandertals, with more sophisticated technologies, expanded resource exploitation, and more complex clothing production. However, recent analyses have indicated that Neandertals were more nuanced in their behavioral adaptations, with the production of the Châtelperronian technocomplex, the processing and cooking of plant foods, and differences in behavioral adaptations according to habitat. This study adds to this debate by addressing the behavioral strategies of EMH (n = 30) within the context of non-dietary anterior tooth-use behaviors to glean possible differences between them and their Neandertal (n = 45) counterparts. High-resolution casts of permanent anterior teeth were used to collect microwear textures of fossil and comparative bioarchaeological samples using a Sensofar white-light confocal profiler with a 100x objective lens. Labial surfaces were scanned, totaling a work envelope of 204 x 276 μm for each individual. The microwear textures were examined for post-mortem damage and uploaded to SSFA software packages for surface characterization. Statistical analyses were performed to examine differences in central tendencies and distributions of anisotropy and textural fill volume variables among the EMH sample itself by habitat, location, and time interval, and between the EMH and Neandertal samples by habitat and location. Descriptive statistics for the EMH sample were compared to seven bioarchaeological samples (n = 156) that utilized different tooth-use behaviors to better elucidate specific activities that may have been performed by EMH. Results show no significant differences between the means within the EMH sample by habitat, location, or time interval. Furthermore, there are no significant differences found here between EMH and Neandertals. Comparisons to the bioarchaeological samples suggest both fossil groups participated in clamping and grasping activities. These results indicate that EMH and Neandertals were similar in their non-dietary anterior tooth-use behaviors and provide additional evidence for overlapping behavioral strategies employed by these two hominins.

The Neanderthal teeth from Marillac (Charente, Southwestern France): Morphology, comparisons and paleobiology

Few European sites have yielded human dental remains safely dated to the end of MIS 4/beginning of MIS 3. One of those sites is Marillac (Southwestern France), a collapsed karstic cave where archeological excavations (1967-1980) conducted by B. Vandermeersch unearthed numerous faunal and human remains, as well as a few Mousterian Quina tools. The Marillac sinkhole was occasionally used by humans to process the carcasses of different prey, but there is no evidence for a residential use of the site, nor have any hearths been found. Rare carnivore bones were also discovered, demonstrating that the sinkhole was seasonally used, not only by Neanderthals, but also by predators across several millennia. The lithostratigraphic units containing the human remains were dated to ∼60 kyr. The fossils consisted of numerous fragments of skulls and jaws, isolated teeth and several post-cranial bones, many of them with traces of perimortem manipulations. For those already published, their morphological characteristics and chronostratigraphic context allowed their attribution to Neanderthals. This paper analyzes sixteen unpublished human teeth (fourteen permanent and two deciduous) by investigating the external morphology and metrical variation with respect to other Neanderthal remains and a sample from modern populations. We also investigate their enamel thickness distribution in 2D and 3D, the enamel-dentine junction morphology (using geometric morphometrics) of one molar and two premolars, the roots and the possible expression of taurodontism, as well as pathologies and developmental defects. The anterior tooth use and paramasticatory activities are also discussed. Morphological and structural alterations were found on several teeth, and interpreted in light of human behavior (tooth-pick) and carnivores' actions (partial digestion). The data are interpreted in the context of the available information for the Eurasian Neanderthals.

Digital enhancement of dental enamel microstructure images from intact teeth

Dental enamel is formed by rod-like structures, the enamel prisms. Groups of prisms are packed together in successive horizontal layers of alternating directions, known as Hunter-Schreger bands (HSBs). HSBs are the major microstructural characteristic of mammalian enamel. The pattern of HSBs can vary among mammalian species and this variability may provide relevant information regarding the species life history and taxon identification. In human HSBs can be used as a biometric-based parameter for personal identification in automated systems. The analysis of HSBs has been hampered by technical difficulties. The low contrast between light and dark bands and variations in light intensity may hinder the observation of HSBs in digital images. This article describes a simple and efficient computational procedure that greatly enhances the contrast and minimizes the differences in the intensity of illumination in HSBs images. Its use can significantly increase the quality and the number of HSBs that can be recorded in intact teeth.

Optimizing the analysis of dental enamel microstructure in intact teeth

In most mammalian species enamel prisms are regularly arranged in layers of alternating directions forming an angle of approximately 90°. These successive layers of prisms are known as Hunter-Schreger bands (HSBs). The analysis of HSBs may provide valuable information regarding the species life history, taxon and personal identification, with evident applicability in physical anthropology and forensics. Obtaining good quality digital images of HSBs in intact specimens is not always a feasible task. The major problems are the low contrast of images; the reflection of incident light, which may create areas of intense shine in digital images; and the abrupt decrease in the degree of illumination that occurs after light crosses the vertical cracks, frequently present in enamel. We show here that the area of intense shine can be minimized by a polarizing filter coupled to the camera objective, and the filling of enamel cracks with corn oil can reduce refraction of light in enamel cracks. These procedures can significantly increase the quality and the area of HSBs that can be recorded in intact teeth.

The late Early Pleistocene human dental remains from Uadi Aalad and Mulhuli-Amo (Buia), Eritrean Danakil: macromorphology and microstructure

Fieldwork performed during the last 15 years in various Early Pleistocene East African sites has significantly enlarged the fossil record of Homo erectus sensu lato (s.l.). Additional evidence comes from the Danakil Depression of Eritrea, where over 200 late Early to early Middle Pleistocene sites have been identified within a ∼1000 m-thick sedimentary succession outcropping in the Dandiero Rift Basin, near Buia. Along with an adult cranium (UA 31), which displays a blend of H. erectus-like and derived morpho-architectural features and three pelvic remains, two isolated permanent incisors (UA 222 and UA 369) have also been recovered from the 1 Ma (millions of years ago) Homo-bearing outcrop of Uadi Aalad. Since 2010, our surveys have expanded to the nearby (4.7 km) site of Mulhuli-Amo (MA). This is a fossiliferous area that has been preliminarily surveyed because of its exceptional concentration of Acheulean stone tools. So far, the site has yielded 10 human remains, including the unworn crown of a lower permanent molar (MA 93). Using diverse analytical tools (including high resolution μCT and μMRI), we analysed the external and internal macromorphology and microstructure of the three specimens, and whenever possible compared the results with similar evidence from early Homo, H. erectus s.l., H. antecessor, H. heidelbergensis (from North Africa), Neanderthals and modern humans. We also assessed the UA 369 lower incisor from Uadi Aalad for root completion timing and showed that it compares well with data for root apex closure in modern human populations.