Australopithecus afarensis endocasts suggest ape-like brain organization and prolonged brain growth

Human brains are three times larger, are organized differently, and mature for a longer period of time than those of our closest living relatives, the chimpanzees. Together, these characteristics are important for human cognition and social behavior, but their evolutionary origins remain unclear. To study brain growth and organization in the hominin species Australopithecus afarensis more than 3 million years ago, we scanned eight fossil crania using conventional and synchrotron computed tomography. We inferred key features of brain organization from endocranial imprints and explored the pattern of brain growth by combining new endocranial volume estimates with narrow age at death estimates for two infants. Contrary to previous claims, sulcal imprints reveal an ape-like brain organization and no features derived toward humans. A comparison of infant to adult endocranial volumes indicates protracted brain growth in A. afarensis, likely critical for the evolution of a long period of childhood learning in hominins

Anterior dental loading and root morphology in Neanderthals

Distinguer les incisives et canines des Néanderthaliens de celles des hommes modernes peut représenter un défi dans le cas de dents isolées trouvées dans des collections de musée, ou provenant de contextes stratigraphiques perturbés. De plus, la morphologie de la couronne ne peut être utilisée dans le cas de dents fortement usées. Une étude préliminaire basée sur des échantillons limités et des mesures linéaires (Bailey, 2005) propose que la longueur des racines dentaires à elle seule permet de discriminer taxonomiquement les Néanderthaliens des hommes modernes du Paléolithique supérieur et actuels. Cette thèse teste cette hypothèse pour un échantillon de Néanderthaliens et d'hommes modernes, plus large géographiquement et chronologiquement, en utilisant la micro-tomographie. En plus de l'intérêt taxonomique d'explorer la taille et la forme des racines, nous discutons les implications fonctionnelles de la morphologie racinaire des dents antérieures dans le contexte de l'hypothèse des " dents-utilisées-comme-des-outils ", et des activités para-masticatrices. La première partie a été publiée comme suit : Le Cabec, A., Kupczik, K., Gunz, P., Braga, J., and Hublin, J.J. (2012). Long Anterior Mandibular Tooth Roots in Neanderthals Are Not the Result of their Large Jaws. Journal of Human Evolution, pp. 63, 667-681. DOI: 10.1016/j. jhevol.2012.07.003. Cette partie valide la longueur des racines dentaires en tant qu'outil taxonomique pour distinguer les Néanderthaliens tardifs des hommes modernes du Paléolithique Supérieur et récents. En dépit de l'absence de corrélation entre la taille des racines et la taille de la symphyse mentonnière, les Néanderthaliens ont de grandes racines, pour la taille de leurs mâchoires. Il est alors proposé que les courtes racines des hommes modernes récents résulteraient d'une allométrie négative. La seconde partie a été publiée comme suit : Le Cabec, A., Gunz, P., Kupczik, K., Braga, J. and Hublin, J.J. (2013). Anterior Tooth Root Morphology and Size in Neanderthals: Taxonomic and Functional Implications. Journal of Human Evolution, 64, pp. 169-193. DOI: 10.1016/j. jhevol.2012.08.011. La morphologie racinaire est étudiée à travers un large échantillon d'hominidés fossiles et actuels, couvrant une large période chronologique et une vaste zone géographique. Les plus grandes longueurs racinaires observées chez les Néanderthaliens peuvent avoir résulté de la rétention d'une condition ancestrale. L'attribution taxonomique débattue de certains spécimens est discutée à la lumière de la morphologie racinaire des dents antérieures et montre que la longueur racinaire seule ne devrait pas être considérée comme suffisante pour une diagnose taxonomique. La fréquente présence d'hypercémentose et sa distribution non-homogène autour de l'apex racinaire pour les dents antérieures des Néanderthaliens pourrait refléter le régime de charge exercé sur les dents antérieures, probablement utilisées comme une troisième main.Distinguishing Neanderthal and modern human incisors and canines can be challenging in the case of isolated teeth found in museum collections, or from unclear stratigraphic contexts. In addition, the crown morphology cannot be used in the case of heavily worn teeth. A preliminary study based on limited samples and linear measurements (Bailey, 2005) proposed that root length alone can taxonomically discriminate Neanderthals from Upper Paleolithic and extant modern humans. This thesis investigates whether this remains true for a broader chronological and geographical sample of Neanderthals and modern humans, using micro-computed tomography. In addition to the taxonomic interest of investigating root size and shape, we discuss the functional implications of the anterior root morphology in the context of the 'teeth-as-tools' hypothesis and of para-masticatory activities. The first part was published as: Le Cabec, A., Kupczik, K., Gunz, P., Braga, J., and Hublin, J.J. (2012). Long Anterior Mandibular Tooth Roots in Neanderthals Are Not the Result of their Large Jaws. Journal of Human Evolution, 63, pp. 667-681. DOI: 10.1016/j.jhevol.2012.07.003. This part validates root length as a taxonomical tool to distinguish late Neanderthals from Upper Paleolithic and recent modern humans. Despite the absence of correlation between root size and symphyseal size, Neanderthals have large roots for the size of their jaws. It is hypothesized that the short roots of extant modern humans result from a negative allometry. The second part was published as: Le Cabec, A., Gunz, P., Kupczik, K., Braga, J. and Hublin, J.J. (2013). Anterior Tooth Root Morphology and Size in Neanderthals: Taxonomic and Functional Implications. Journal of Human Evolution, 64, pp. 169-193. DOI: 10.1016/j. jhevol.2012.08.011. Root morphology is explored across a chronologically and geographically large sample of fossil and extant hominids. Longer roots in Neanderthals may have resulted from the retention of an ancestral condition. The debated taxonomic attribution of some specimens is discussed in light of anterior tooth root morphology and shows that root length alone should not be sufficient for taxonomic diagnosis. The frequent presence of hypercementosis and its non-homogeneous distribution around the root apex in Neanderthal anterior teeth could reflect the loading regime exerted on the front teeth, likely used as a third hand

Impacts of curatorial and research practices on the preservation of fossil hominid remains

International audienceFossil remains are the only physical evidence of past forms of life which researchers can use to study the evolutionary biology of a species, especially regarding the human lineage. We review and consider the way in which the conditions surrounding a fossil’s discovery and its use for scientific research impacts its long-term preservation. The deterioration of the body starts soon after death, continues in the sediments and only a subsample of the anatomical elements will persist and may finally be unearthed by archeologists. From their recovery onwards, fossil remains are exposed to many sources of further damage: from handling, restoration, measuring to invasive sampling. On the one hand, curators are faced with the inherent challenge of balancing their responsibility to protect fossil specimens with allowing researchers to perform specific analyses or invasive sampling detrimental to the preservation of the fossil. On the other hand, scientists may find their analyses complicated by multiple factors including taphonomy, or restoration techniques (e.g., consolidants, cleaning chemicals). We provide several historical examples illustrating the complex nature of the factors acting on fossil preservation. We discuss concerns about producing and sharing (digital) data from fossils. Finally, we also suggest and support some curatorial practices which maximize the traceability of treatments underwent by a fossil

Transcriptional patterns associated with BDCA3 expression on BDCA1+ myeloid dendritic cells

Myeloid dendritic cells, including BDCA3hi DCs and BDCA1+ DCs (hereafter dubbed DC1 and DC2 for clarity), play a pivotal role in the induction and regulation of immune responses. Interestingly, a fraction of DC2 also express low to intermediate levels of BDCA3. It is unknown whether BDCA3+ DC2 also share other traits with DC1 that are absent in BDCA3- DC2 and/or whether BDCA3 expression renders DC2 functionally distinct from their BDCA3-lacking counterparts. Here, we used expression analysis on a predefined set of immunology-related genes to determine divergence between BDCA3-positive and BDCA3-negative DC2 and their relation to bona fide BDCA3hi DC1. Results showed that mRNA fingerprints of BDCA3+ DC2 and BDCA3- DC2 are very similar, and clearly distinct from that of DC1. Differences in mRNA expression, however, were observed between BDCA3+ DC2 and BDCA3- DC2 that pointed toward a more activated status of BDCA3+ DC2. In line with this, higher steady state maturation marker expression and TLR-induced maturation marker expression and inflammatory cytokine production by BDCA3+ DC2 were observed. This dataset provides insight into the relationship between myeloid DC populations and contributes to further understanding of DC immunobiology

Dental development and age at death of the holotype of Anapithecus hernyaki (RUD 9) using synchrotron virtual histology

The chronology of dental development and life history of primitive catarrhines provides a crucial comparative framework for understanding the evolution of hominoids and Old World monkeys. Among the extinct groups of catarrhines are the pliopithecoids, with no known descendants. Anapithecus hernyaki is a medium-size stem catarrhine known from Austria, Hungary and Germany around 10 Ma, and represents a terminal lineage of a clade predating the divergence of hominoids and cercopithecoids, probably more than 30 Ma. In a previous study, Anapithecus was characterized as having fast dental development. Here, we used non-destructive propagation phase contrast synchrotron micro-tomography to image several dental microstructural features in the mixed mandibular dentition of RUD 9, the holotype of A. hernyaki. We estimate its age at death to be 1.9 years and describe the pattern, sequence and timing of tooth mineralization. Our results do not support any simplistic correlation between body mass and striae periodicity, since RUD 9 has a 3-day periodicity, which was previously thought unlikely based on body mass estimates in Anapithecus. We demonstrate that the teeth in RUD 9 grew even faster and initiated even earlier in development than suggested previously. Permanent first molars and the canine initiated 49 and 38 days prenatally, respectively. These results contribute to a better understanding of dental development in Anapithecus and may provide a window into the dental development of the last common ancestor of hominoids and cercopithecoids

The versatile functions of complement C3-derived ligands

The complement system is a major component of immune defense. Activation of the complement cascade by foreign substances and altered self-structures may lead to the elimination of the activating agent, and during the enzymatic cascade, several biologically active fragments are generated. Most immune regulatory effects of complement are mediated by the activation products of C3, the central component. The indispensable role of C3 in opsonic phagocytosis as well as in the regulation of humoral immune response is known for long, while the involvement of complement in T-cell biology have been revealed in the past few years. In this review, we discuss the immune modulatory functions of C3-derived fragments focusing on their role in processes which have not been summarized so far. The importance of locally synthesized complement will receive special emphasis, as several immunological processes take place in tissues, where hepatocyte-derived complement components might not be available at high concentrations. We also aim to call the attention to important differences between human and mouse systems regarding C3-mediated processes. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Lt

Growth and development of the third permanent molar in Paranthropus robustus from Swartkrans, South Africa

Third permanent molars (M3s) are the last tooth to form but have not been used to estimate age at dental maturation in early fossil hominins because direct histological evidence for the timing of their growth has been lacking. We investigated an isolated maxillary M3 (SK 835) from the 1.5 to 1.8-million-year-old (Mya) site of Swartkrans, South Africa, attributed to Paranthropus robustus. Tissue proportions of this specimen were assessed using 3D X-ray micro-tomography. Thin ground sections were used to image daily growth increments in enamel and dentine. Transmitted light microscopy and synchrotron X-ray fluorescence imaging revealed fluctuations in Ca concentration that coincide with daily growth increments. We used regional daily secretion rates and Sr marker-lines to reconstruct tooth growth along the enamel/dentine and then cementum/dentine boundaries. Cumulative growth curves for increasing enamel thickness and tooth height and age-of-attainment estimates for fractional stages of tooth formation differed from those in modern humans. These now provide additional means for assessing late maturation in early hominins. M3 formation took ≥ 7 years in SK 835 and completion of the roots would have occurred between 11 and 14 years of age. Estimated age at dental maturation in this fossil hominin compares well with what is known for living great apes

Un cas d’exposition au musée Fabre. « Dans le Secret des œuvres d’art »

L’exposition « Dans le Secret des œuvres d’art » présentée en 2018 au musée Fabre proposait au visiteur de découvrir l’étude matérielle et la restauration de plusieurs œuvres des collections du musée montpelliérain. L’objectif de l’exposition était d’apprendre au visiteur à observer la matière de l’œuvre et proposait ainsi un ensemble de médiums, huile sur toile, huile sur bois, dessin sur papier, fonte en bronze et toile libre en matériaux contemporains, comme autant de « cas » matériels à découvrir. La complexité de nombreuses opérations évoquées par l’exposition a impliqué un important usage des ressources du numérique. Des applications interactives, courts-métrages, modélisation 3D, vidéos pédagogiques et mapping étaient disséminés tout au long du parcours de visite, proposant un usage du numérique particulièrement pertinent, permettant de découvrir au plus près la singularité matérielle des œuvres exposées.The exhibition « Dans le Secret des œuvres d’art », which took place in 2018 at the musée Fabre, offered visitors to discover the material study and the conservation of several works from the collections of the Montpellier museum. The purpose of the exhibition was to teach the visitor to observe the material aspect of the artworks and offered a set of mediums (oil on canvas, oil on wood panel, drawing on paper, bronze cast and free canvas in contemporary materials), as material « cases » to discover. The complexity of many operations evoked by the exhibition implied an important use of digital resources. Interactive applications, short films, 3D modeling, educational videos and mapping were disseminated throughout the visit trail, offering a particularly relevant use of digital tools, allowing to discover as closely as possible the material singularity of the artworks on display

3D enamel thickness in Neandertal and modern human permanent canines

Enamel thickness figures prominently in studies of human evolution, particularly for taxonomy, phylogeny, and paleodietary reconstruction. Attention has focused on molar teeth, through the use of advanced imaging technologies and novel protocols. Despite the important results achieved thus far, further work is needed to investigate all tooth classes. We apply a recent approach developed for anterior teeth to investigate the 3D enamel thickness of Neandertal and modern human (MH) canines. In terms of crown size, the values obtained for both upper and lower unworn/slightly worn canines are significantly greater in Neandertals than in Upper Paleolithic and recent MH. The 3D relative enamel thickness (RET) is significantly lower in Neandertals than in MH. Moreover, differences in 3D RET values between the two groups appear to decrease in worn canines beginning from wear stage 3, suggesting that both the pattern and the stage of wear may have important effects on the 3D RET value. Nevertheless, the 3D average enamel thickness (AET) does not differ between the two groups. In both groups, 3D AET and 3D RET indices are greater in upper canines than in lower canines, and overall the enamel is thicker on the occlusal half of the labial aspect of the crown, particularly in MH. By contrast, the few early modern humans investigated show the highest volumes of enamel while for all other components of 3D enamel, thickness this group holds an intermediate position between Neandertals and recent MH. Overall, our study supports the general findings that Neandertals have relatively thinner enamel than MH (as also observed in molars), indicating that unworn/slightly worn canines can be successfully used to discriminate between the two groups. Further studies, however, are needed to understand whether these differences are functionally related or are the result of pleiotropic or genetic drift effects