Variation and Characteristics of the Cranial Vault Thickness in the Krapina and Western European Neandertals

The Krapina collection constitutes the largest sample of Neandertal individuals. However, comparisons of these fossils with other Western European Neandertals have been limited because of the fragmentary condition of the Krapina specimens and because gracility and small dimensions of the cranial remains were attributed to phylogeny and to geological age or to a sex/age bias in the composition of the sample. This study focuses on cranial vault thickness to document new evidence on its variation in the Neandertals. The results demonstrate the similarities between Krapina and the Western European Neandertals in thickness of the cranial vault along the mid-sagittal plane. Finally, Neandertals have characteristics that distinguish them from anatomically modern Homo sapiens fossils

Are thickened cranial bones and equal participation of the three structural bone layers autapomorphic traits of Homo erectus?

Numerous studies have proposed different lists of morphological features to define the species of Homo erectus; among these, some are considered to be autapomorphic. The intention of this study is to discuss two of these possible autapomorphic traits: thickened cranial bones and equal participation of the three structural bone layers (inner and outer tables, diploe) in this thickening. This study brings new information concerning cranial vault thickness and structural composition in the mid-sagittal plane of some Asian Homo erectus. The Ngandong and Sambungmacan fossils, as well as the Zhoukoudian and Sangiran individuals, have cranial vault thickness values within the range of variation observed in our Homo sapiens comparative sample. Moreover, even if the frontal and sagittal keels in Homo erectus constitute a relief on the external cranial vault surface, they do not necessary correspond to a real thickening of the underlying bone. The diploic layer principally contributes to their internal composition. Similarly, the diploe constitutes the greatest part of the total vault thickness along the mid-sagittal plane, particularly in the frontal and occipital tori, in the analysed fossils of this extinct species. Finally, our results show that Homo erectus individuals have cortical tables as well as diploe variation and distribution patterns similar to anatomically modern Homo sapiens. Therefore, the two tested autapomorphic traits for Homo erectus can no longer be considered as valid. L’épaisseur importante de la voûte crânienne et l’hyperossification de la table compacte externe, deux caractères considérés comme autapomorphiques pour l’espèce Homo erectus, sont étudiés. La variation de l’épaisseur et sa constitution interne ont été analysées le long du plan sagittal médian chez des représentants de l’espèce Homo erectus. Les fossiles de Ngandong, Sambungmacan, Sangiran et Zhoukoudian étudiés ont dans l’ensemble des valeurs d’épaisseur crânienne qui se situent dans la variabilité de notre échantillon d’Hommes anatomiquement modernes. De plus, les fossiles attribués à Homo erectus et Homo sapiens partagent le même schéma de distribution de l’épaisseur crânienne et des tables osseuses le long du plan sagittal médian. Si la carène sagittale chez Homo erectus constitue un relief osseux externe, elle ne correspond pas nécessairement à un réel épaississement de l’os sous-jacent, ni à celui de la table compacte externe comme admis jusque là. Le diploé en compose la majeure partie comme cela est observé sur les torus frontal et occipital transverse. Les caractères testés ne sont donc pas des autapomorphies de l’espèce Homo erectus

Nouvelles données sur les caractéristiques morphologiques immatures du crâne chez les Homo erectus asiatiques

L’identification des spécimens immatures au sein de l’enregistrement fossile est primordial, aussi bien dans la perspective de déterminer la variabilité adulte des différents taxons, que pour aborder leurs caractéristiques ontogénétiques et phylogénétiques. En ce qui concerne les fossiles asiatiques attribués à Homo erectus, seulement quelques restes crâniens d’individus immatures ont été mis au jour et ces spécimens se distribuent sur une très grande période chronologique. Dans ce contexte, l’objectif de cette étude est, d’une part, de tester la validité des caractères généralement employés pour estimer le stade de développement de ces fossiles ; d’autre part, d’apporter des nouvelles données à notre connaissance des caractéristiques morphologiques immatures du squelette céphalique pour l’espèce Homo erectus. L’utilisation des standards de croissance définis chez l’Homme moderne n’apparaît pas appropriée pour étudier la croissance chez Homo erectus et les critères fréquemment utilisés pour discuter du stade de développement chez cette espèce fossile s’avèrent peu significatifs. En effet, les composantes osseuses internes se dissocient précocement et l’épaisseur crânienne peut atteindre la variabilité adulte à un stade de développement immature chez les fossiles asiatiques. Par ailleurs, les variations de forme et de conformation de l’endocrâne entre les spécimens non adultes et adultes chez Homo erectus suivraient une trajectoire différente de celle qui s’observe au cours de la croissance et du développement chez les Hommes modernes.It is critical to be able to recognize the juvenile specimens within the fossil record in order to determine the adult variability of the different taxa and to approach their ontogenetic and phylogenetic characteristics. Nevertheless, with regard to the Asian fossils assigned to Homo erectus, few cranial remains of juvenile individuals have been unearthed. Furthermore, these individuals are spread over a large chronological duration. Our purpose is to test the validity of the features generally used to estimate the developmental age of these fossils and to convey new information about the juvenile features of the cephalic skeleton in the species Homo erectus. Our results illustrate that growth standards defined for modern humans are not suitable to study the growth and development in Homo erectus. Moreover, the criteria frequently used to determine the development stage in Homo erectus would be barely meaningful. We show that the internal components of the cranial vault would differentiate at an early developmental age, as shown by the Mojokerto child. Similarly, cranial vault thickness would come within the adult range of variation early during growth, as shown for the frontal squama by Ngandong 2. The thickness of the frontal superstructures and of the occipital torus would increase later, but before the adult stage. This modification concerns all the internal components of the bone and principally the diploic layer. Moreover, our results suggest that the growth and development of the Homo erectus brain were different from those of modern humans. The transition from the endocranial shape of Mojokerto to the adult morphology for Homo erectus corresponds to a relative development of the frontal lobes, associated with an antero-posterior extension of the cerebral structures. Finally, the globularity of the brain and of the skull would persist late during the ontogenetic history in Homo erectus. The disappearance of these features would be due to an antero-posterior relative elongation of the endocast and of the cranial vault, as well as anterior enlargement of the frontal superstructures and posterior enlargement of the occipital superstructures

La morphologie externe et interne de la région supra-orbitaire est-elle corrélée à des contraintes biomécaniques ? Analyses structurales des populations d’Homo sapiens d’Afalou Bou Rhummel (Algérie) et de Taforalt (Maroc)

Une analyse comparative et complémentaire est menée sur la morphologie externe des régions péri-orbitaires et maxillaires et sur la variabilité de la pneumatisation frontale chez des Hommes anatomiquement modernes du Paléolithique supérieur d’Afalou Bou Rhummel (Algérie) et de Taforalt (Maroc) ayant subi un nombre variable d’avulsions dentaires. Les résultats obtenus montrent que les conséquences de ces mutilations sont limitées à l’os pré-maxillaire. La morphologie adulte de l’os maxillaire n’a pas de modification en fonction du nombre d’incisives ôtées durant l’enfance. De même, celle des régions supra-orbitaires est homogène alors que la pneumatisation frontale, très variable dans son extension, montre une relation dans sa forme avec celle des structures osseuses. Les implications mécaniques liées à l’incision devaient être très variables selon le nombre d’avulsions. Les contraintes correspondantes n’ont pas eu d’influence sur la morphologie de la partie postérieure de l’os maxillaire, ni sur les superstructures de l’os frontal. La pneumatisation est aussi indépendante de ces caractéristiques dentaires et probablement de leurs implications fonctionnelles. Cette approche permet d’argumenter que les contraintes masticatoires ont une influence très limitée sur le développement des superstructures supra-orbitaires et qu’elles n’en sont aucunement la cause principale, au moins chez l’Homme moderne.The purpose of this study was to analyse and compare the external morphology of the supraorbital and maxillary regions as well as the variability of frontal pneumatisation in a sample of anatomically modern humans of the upper Palaeolithic of Afalou Bou Rhummel (Algeria) and Taforalt (Morocco), who underwent extraction of upper incisors. The results of the study show that the consequences of such mutilations are limited to the premaxilla and have no effect on the maxilla or the cranial superstructures. The supraorbital regions are homogeneous. However, the frontal pneumatisation, which is variable in its extension, has a similar morphology to the bone structures. Biomechanical stress has very limited influence on the development of the supraorbital structures, at least in modern humans

Structures internes claviculaires chez Pan, Gorilla et Homo. Méthode d’analyse et résultats préliminaires

Ce travail présente les résultats préliminaires d’une étude sur les structures claviculaires internes, par l’intermédiaire du scanner à rayon X. La morphologie complexe de cet os rend impossible la détermination d’un plan de coupe similaire et reproductible d’un individu à l’autre et interdit ainsi toute analyse classique des données scanographiques bidimensionnelles. Nous proposons un protocole inédit permettant de quantifier de manière précise et répétitive les variations volumiques en trois dimensions des structures morphologiques internes des clavicules. Celles-ci sont dissociées en trois ensembles distincts (structures osseuses denses, structures osseuses peu denses et porosité) en fonction de leur densité radiologique. Les premiers résultats montrent que les structures osseuses denses sont représentées par un volume plus important que les structures osseuses peu denses. De plus, les clavicules de chimpanzé sont caractérisées par un volume relatif des structures osseuses denses plus important que chez les gorilles et les hommes. Ceci s’exprime, entre autres, chez un quart des chimpanzés, par une absence des structures osseuses peu denses au point d’inflexion de la courbure acromiale. Ces différences peuvent être interprétées comme des adaptations aux contraintes subies par les clavicules.This study presents the preliminary results of an examination of internal clavicular structures using CT scan data analysis. The complex morphology of this bone makes the determination of a reproducible CT slice plane impossible and so any classical analysis of the two-dimensional CT data is ruled out. We propose a new protocol which enables quantification in three dimensions of the variations in volume of the internal morphological structures of the clavicles.  These are divided into three distinct groups (porosity, low density structures and high density structures) according to their radiological density. The first results show that the high density structures are represented by a larger volume than the low density structures. Moreover, chimpanzee clavicles are characterized by a relative volume of high density bone structure superior to that of gorillas and humans. For a quarter of chimpanzees, this is characterized by an absence of low density structures at the inflexion point of the acromial curvature. These differences can be interpreted as adaptations to the strains to which the clavicles are subjected

Neandertal-like traits visible in the internal structure of non-supranuchal fossae of some recent Homo sapiens: The problem of their identification in hominins and phylogenetic implications

Although recently the internal structure of the non-supranuchal fossa of Homo sapiens has been described and compared to that observed in the Neandertal suprainiac fossa, until now it has not been examined in any modern human children. In this study, the internal structure of this fossa in the occipital bones of three children (two aged 3–4 years and one aged 5 years ± 16 months) and one adult individual representing recent Homo sapiens from Australia was analysed and compared to that of the Neandertal suprainiac fossa. In order to analyse the internal composition of the fossae of the examined specimens, initially, high-resolution micro-CT datasets were obtained for their occipital bones; next, 3D topographic maps of the variation in thickness of structural layers of the occipital bones were made and 2D virtual sections in the median region of these fossae were prepared. In the fossa of one immature individual, the thinning of the diploic layer characteristic of a Neandertal suprainiac fossa was firmly diagnosed. The other Neandertal-like trait, concerning the lack of substantial thinning of the external table of the bone in the region of the fossa, was established in two individuals (one child and one adult) due to the observation of an irregular pattern of the thickness of this table in the other specimens, suggesting the presence of an inflammatory process. Our study presents, for the first time, Neandertal-like traits (but not the whole set of features that justifies the autapomorphic status of the Neandertal supraniac fossa) in the internal structure of non-supranuchal fossae of some recent Homo sapiens. We discuss the phylogenetic implications of the results of our analysis and stress the reasons that use of the 3D topographic mapping method is important for the correct diagnosis of Neandertal traits of the internal structure of occipital fossae

Computer tomography scanning of Homo erectus crania Ngandong 7 from Java: Internal structure, paleopathology and post-mortem history

ABSTRACT Antoine Balzeau, Etty Indriati, Dominique Grimaud-Herve, Teuku Jacob - Computer tomography scanning of Homo Erectus crania Ngandong 7 from Java: Internal structure, paleopathology and post-mortem history Background: Computer Tomography scanning has recently been a tool for diagnosis of normal anatomy and pathology in medical sciences. The CT method has also been applied in ancient human skeletal remains and yield good results for researching the morphology, pathology, and postfossilization bone alteration. Paleoanthropological evidences exhibit that biological remains sometimes are fossilised, thus enabling the pursuit of scientific inquiries in regard to anatomy and biology of ancient humans. Aim of study: to know the morphology and anatomy of the crania including the internal structures that is not feasible\u27 in external bone study, such air pneumatisation, the shape of frontal sinuses, and thickness of the external table, diploe, or the internal table. This study also aims to know the mineralization distribution as a result of fossilization. Material and Method: The material in this study was a fossil crania of Ngandong 7 that belongs to the latest representation of the Homo erectus from Ngandong, East Java, Indonesia. Ng 7 is from the Late Pleistocene period dated about 27,000 to 100,000 years ago. The CT scan was conducted in the QuinzeVingts hospital, Paris, in January 2001. The method used is by applying a medical CT-based data in order to extract the maximum information concerning mineralization, internal cranial features, osseous distribution and disease. An adapted acquisition and analysis protocols are developed from the CT scan. Results: Mineralization of Ng 7 occurred during fossilization, causing the diploe to be thickened than normally in antemortem and prefosilization periods. Because of post-mortem transformation of the individual structures, many slices of CT scans were necessary. The internal structures showed ovoid shape of frontal sinuses, and well developed pneumatisation of the mastoid region. Cracks were detected as a result of postfosilization compressions. Lesions appeared on CT scan just posterior to the bregma in the form of eroded external table. This caused diffuse boundary between external table, diploe, and internal table due to homogenous mineralization Conclusion: It is concluded that the Ngandong 7 Homo erectus shares internal morphological similarities with other Ngandong and Sambungmacan fossils and presents lesions that might have caused by pathology during the life of the individual. The post-mortem history of this fossil appears to be composed of at least two distinct stages with osseous loss and fluvial transport, followed by taphonomic and diagenetic processes. Key words: Ngandong, Homo erectus, computer tomography, paleopathology, post-mortem histor

Shared Pattern of Endocranial Shape Asymmetries among Great Apes, Anatomically Modern Humans, and Fossil Hominins

Anatomical asymmetries of the human brain are a topic of major interest because of their link with handedness and cognitive functions. Their emergence and occurrence have been extensively explored in human fossil records to document the evolution of brain capacities and behaviour. We quantified for the first time antero-posterior endocranial shape asymmetries in large samples of great apes, modern humans and fossil hominins through analysis of “virtual” 3D models of skull and endocranial cavity and we statistically test for departures from symmetry. Once based on continuous variables, we show that the analysis of these brain asymmetries gives original results that build upon previous analysis based on discrete traits. In particular, it emerges that the degree of petalial asymmetries differs between great apes and hominins without modification of their pattern. We indeed demonstrate the presence of shape asymmetries in great apes, with a pattern similar to modern humans but with a lower variation and a lower degree of fluctuating asymmetry. More importantly, variations in the position of the frontal and occipital poles on the right and left hemispheres would be expected to show some degree of antisymmetry when population distribution is considered, but the observed pattern of variation among the samples is related to fluctuating asymmetry for most of the components of the petalias. Moreover, the presence of a common pattern of significant directional asymmetry for two components of the petalias in hominids implicates that the observed traits were probably inherited from the last common ancestor of extant African great apes and Homo sapiens

Reassessment of the Neandertal fossil collection from Abri Suard (La Chaise de Vouthon, Charente, France)

Abri Suard is one of the sites localized at La Chaise de Vouthon in Charente. La Chaise is a well-known prehistoric place, historically and archaeologically as it preserved long stratigraphic sequences documenting Lower to Upper Palaeolithic human occupations. A substantial number of Neandertal human remains have been discovered in a sedimentary unit associated to MIS 6-5 (250-120 kya) from Abri Suard, which makes them some of the earliest Western European Neandertals. Although most of the Ne..

What do brain endocasts tell us? A comparative analysis of the accuracy of sulcal identification by experts and perspectives in palaeoanthropology

Palaeoneurology is a complex field as the object of study, the brain, does not fossilize. Studies rely therefore on the (brain) endocranial cast (often named endocast), the only available and reliable proxy for brain shape, size and details of surface. However, researchers debate whether or not specific marks found on endocasts correspond reliably to particular sulci and/or gyri of the brain that were imprinted in the braincase. The aim of this study is to measure the accuracy of sulcal identification through an experiment that reproduces the conditions that palaeoneurologists face when working with hominin endocasts. We asked 14 experts to manually identify well-known foldings in a proxy endocast that was obtained from an MRI of an actual in vivo Homo sapiens head. We observe clear differences in the results when comparing the non-corrected labels (the original labels proposed by each expert) with the corrected labels. This result illustrates that trying to reconstruct a sulcus following the very general known shape/position in the literature or from a mean specimen may induce a bias when looking at an endocast and trying to follow the marks observed there. We also observe that the identification of sulci appears to be better in the lower part of the endocast compared to the upper part. The results concerning specific anatomical traits have implications for highly debated topics in palaeoanthropology. Endocranial description of fossil specimens should in the future consider the variation in position and shape of sulci in addition to using models of mean brain shape. Moreover, it is clear from this study that researchers can perceive sulcal imprints with reasonably high accuracy, but their correct identification and labelling remains a challenge, particularly when dealing with extinct species for which we lack direct knowledge of the brain