Sexual dimorphism in the first rib of Homo sapiens.

This work aimed to study sexual dimorphism in the first rib of modern humans, with a special focus on whether differences in shape are due to divergent allometric growth in males and females. Also, we compare the accuracy of sex classification using different approaches based on two methodologies, traditional morphometry based on linear measurements and geometric morphometric analysis based on 2D landmark coordinates. The sample studied here comprised 121 right and left first ribs from 65 female and male adult recent Euro-American Homo sapiens individuals. For traditional morphometrics, 12 metric variables were collected from each rib using a digital caliper, and for geometric morphometrics, six landmarks and 31 semilandmarks were captured from photographs using digital software. Both geometric morphometric and metric data were analyzed to calculate the index of sexual dimorphism, variation related to lateral asymmetry, variation in size and shape, and allometric trends between males and females. Finally, a linear discriminant analysis (LDA) was performed comparing both methodologies to test the best approach for sex classification. Results indicated that there are significant sex differences in the size and shape of the first ribs of recent Euro-American Homo sapiens. Regression analysis revealed different allometric patterns for males and females, and this could partially explain shape differences between sexes. Additionally, traditional morphometrics showed that all characteristics analyzed are significantly dimorphic, with the midshaft minimum craniocaudal diameter, the sternal end minimum diameter, and the neck minimum craniocaudal diameter displaying the most dimorphic scores. Similarly, geometric morphometrics results indicated that males have more curved and interno-exteriorly wider first ribs. Finally, analysis of sex classification using LDA yielded slightly better accuracy for traditional morphometry (83.8%) than the geometric morphometrics approach (81.3%) based on form Procrustes coordinates. This study demonstrates the usefulness of applying two different morphometric approaches to obtain more comprehensive results.

Covariation between the cranium and the cervical vertebrae in hominids.

The analysis of patterns of integration is crucial for the reconstruction and understanding of how morphological changes occur in a taxonomic group throughout evolution. These patterns are relatively constant; however, both patterns and the magnitudes of integration may vary across species. These differences may indicate morphological diversification, in some cases related to functional adaptations to the biomechanics of organisms. In this study, we analyze patterns of integration between two functional and developmental structures, the cranium and the cervical spine in hominids, and we quantify the amount of divergence of each anatomical element through phylogeny. We applied these methods to three-dimensional data from 168 adult hominid individuals, summing a total of more than 1000 cervical vertebrae. We found the atlas (C1) and axis (C2) display the lowest covariation with the cranium in hominids (Homo sapiens, Pan troglodytes, Pan paniscus, Gorilla gorilla, Gorilla beringei, Pongo pygmaeus). H. sapiens show a relatively different pattern of craniocervical correlation compared with chimpanzees and gorillas, especially in variables implicated in maintaining the balance of the head. Finally, the atlas and axis show lower magnitude of shape change during evolution than the rest of the cervical vertebrae, especially those located in the middle of the subaxial cervical spine. Overall, results suggest that differences in the pattern of craniocervical correlation between humans and gorillas and chimpanzees could reflect the postural differences between these groups. Also, the stronger craniocervical integration and larger magnitude of shape change during evolution shown by the middle cervical vertebrae suggests that they have been selected to play an active role in maintaining head balance.

Evolutionary selection and morphological integration in the vertebral column of modern humans.

OBJECTIVES: The main objective is to quantify integration, modularity, and response to selection in the presacral vertebral column of modern humans. MATERIALS AND METHODS: Seventeen linear variables on each presacral vertebra were collected in 108 modern humans producing a total of ~39,000 measurements. Then, we studied patterns and magnitudes of integration at regional, vertebral, and intra-vertebral levels. Additionally, we calculated the ability of vertebrae to respond to selection by quantifying differences in evolvability, flexibility, and constraint throughout the spine. RESULTS: The results indicate that caudal vertebrae are more evolvable than those located more cranially in the presacral vertebral column, following an increasing pattern of evolvability from the cervical to the lumbar region. Additionally, the atlas and fifth lumbar vertebra show the lowest values of integration, while central thoracic vertebrae display the highest magnitudes of integration. DISCUSSION: These results could be related to three main factors: body plan organization expressed by the Hox genes, the strong developmental constraints that determine the number of mammalian vertebrae, and, finally, the functional requirements of an adaptation to bipedal locomotion in the human lineage.

Ancient mitochondrial DNA from the middle neolithic necropolis of Obernai extends the genetic influence of the LBK to west of the Rhine.

OBJECTIVES: The arrival of Neolithic farmers in Europe was the source of major cultural and genetic transitions. Neolithic settlers brought a new set of maternal lineages (mitochondrial DNA), recently well-characterized on the continental road, from the Balkans to West Germany (Rhine River). In the present study, the first mitochondrial DNA data from groups associated with this continental expansion wave located west of the Rhine River has been provided and their genetic affinities with contemporary groups have been discussed. MATERIAL AND METHODS: The mitochondrial DNA analysis of 27 human remains originating from Obernai (5,000-4,400 cal. BC), a necropolis located in French Alsace Region and attributed to Grossgartach, Planig-Friedberg, and Roessen cultures was conducted. RESULTS AND DISCUSSION: Among the 27 individuals studied, 15 HVR-I sequences and 17 mitochondrial haplogroups could be determined. The analysis of the Obernai gene pool clearly confirmed the genetic homogeneity of Linearbandkeramik (LBK) groups on both sides of the Rhine River. Notably, one N1a sequence found in Obernai is shared with LBK farmers from Central Europe, including one individual from the Flomborn site located approximately 200 km north-east of Obernai. On the whole, data gathered so far showed major genetic influence of the Danubian wave from Transdanubia to Atlantic French Coast, going by Alsace Region. However, the genetic influence of descendants from the Mediterranean Neolithic expansion and the significant hunter-gatherer admixture detected further west in the Paris Basin were not perceived in the Obernai necropolis. CONCLUSIONS: Genetic homogeneity and continuity within LBK groups can be proposed on both sides of the Rhine River for the middle Neolithic groups. Nevertheless, mitochondrial data gathered so far for Neolithic groups from the entire extant French Territory clearly point out the complexity and the variability of Neolithic communities interactions that is worthy of further investigation.

How geographical origin and dietary habits interact with the shape of cortical mandibular sections? A geometric morphometrics study in an archaeological context.

OBJECTIVE: Mandibular shape is strongly influenced by biomechanics, particularly during dietary shifts that often occurred in past populations. The relationship is considered extremely complex as development of the mandible is a multifactorial process. Since cortical bone distribution is purportedly more biomechanically sensitive than external shape, comparison of its distribution in past populations can provide new input to understand this complex relationship. The present study examined the effects of geographical origin and dietary habits on the internal anatomy of the mandibular corpus and symphysis. DESIGN: A morphometric analysis was conducted on 72 mandibles from different populations, sampled by their geographical origin and subsistence strategies. Procrustes ANOVAs were performed to test the impact of section-plane location, geographical origin, and dietary habits on the groups' shapes. RESULTS: The specimens' geographical origin and dietary habits had a significant effect on the shapes of the sections (Generalized Goodall F-test, F = 3.2745, df = 6, 304: p < 0.001 and F = 3.7007, df = 4, 306: p < 0.001). CONCLUSION: Geographical origin and dietary habits influenced the shape of the mandibular sections in our sample. These relationships become more complex when analysed in isolated sections. Indeed, this study revealed that symphysis sections could be predominantly influenced by individual variables, whereas intermediate sections of the corpus could be predominantly influenced by populational variables. Future studies could focus on specific sections to better identify the specific "rules of dependence" in each cross-section.

Is the distribution of cortical bone in the mandibular corpus and symphysis linked to loading environment in modern humans? A systematic review.

OBJECTIVE: The human mandible is a unique bone with specific external and internal morphological characteristics, influenced by a complex and challenging loading environment. Mandibular cortical thickness distribution in cross-sections is reported to be related to facial divergence patterns, cultural and dietary habits and more generally, specific loading environment. This review hypothesises that a process of environmental mechanical sensitivity is involved in the distribution of cortical bone in the mandibular corpus and symphysis in modern humans, and that loading regimes can influence this distribution pattern. Based on a review of the recent literature, this study aims to answer the following question: "Is the distribution of cortical bone in the mandibular corpus and symphysis linked to the loading environment in modern humans?" DESIGN: A systematic review was undertaken using the PubMed/Medline, Scopus and Cochrane Library databases for publications from 1984 to 2022 investigating the relationship between cortical bone distribution in the mandibular corpus and the loading environment. A subgroup meta-analysis was performed to determine the overall effect of facial divergence on cortical thickness. RESULTS: From a total of 2791 studies, 20 fulfilled the inclusion criteria. The meta-analyses were performed in eight studies using a randomised model, finding a significant overall effect of facial divergence on cortical thickness in posterior areas of the mandible (p < 0.01). CONCLUSIONS: Within the limitations of this review, specific loading regimes and their consequent variables (diet, culture, facial divergence) were linked to cortical thickness distribution. Sex was found to be unrelated to cortical thickness pattern.

What do we currently need to know about molar incisor hypomineralisation (MIH) and hypomineralized second primary molars (HSPM)? / Que faut-il savoir, à l'heure actuelle, sur les hypominéralisations molaires incisives (MIH) et les hypominéralisations des secondes molaires temporaires (HSPM) ?

Introduction: Molar incisor hypomineralization (MIH) and hypomineralized second primary molars (HSPM) are qualitative and asymmetric enamel defects. MIH affect at least one permanent first molar and can also be associated with permanent incisors. HSPM affect at least one primary second molar and possibly primary canines. Hypomineralized enamel is characteristic: the enamel prisms are disorganized, less distinct, the interprismatic space is more marked, the mineral density is decreased and the protein content is increased. Currently, etiologies remain unknown but the various studies tend towards a multifactorial model with several systemic, genetic and/or epigenetic factors, acting in a synergistic or additive way. Material and Method: The authors highlight the various factors involved in diagnosing MIH and HSPM. A review of the prevalence (French and worldwide) and etiologies of these pathologies is also provided, to enable practitioners to answer any questions parents may have. Conclusion: The knowledge of these different elements on diagnosis, structure, prevalence and etiologies will allow the orthodontist to better collaborate with the dentist but also with the parents in order to ensure an adequate dental and orthodontic management.

Introduction: L'hypominéralisation molaire incisive (MIH) et l'hypominéralisation des secondes molaires temporaires (HSPM) sont des défauts qualitatifs et asymétriques de l'émail. Les MIH affectent au moins une première molaire permanente et peuvent également être associées aux incisives permanentes. Les HSPM affectent au moins une deuxième molaire temporaire et éventuellement les canines temporaires. L'émail hypominéralisé est caractéristique : les prismes d'émail sont désorganisés, moins distincts, l'espace interprismatique est plus marqué, la densité minérale est diminuée et la teneur en protéines augmentée. Actuellement, les étiologies restent méconnues mais les différentes études tendent vers un modèle multifactoriel avec plusieurs facteurs systémiques, génétiques et/ou épigénétiques, agissant de manière synergique ou additive. Matériel et méthode: Les auteurs mettent en avant les différents éléments permettant le diagnostic des MIH et des HSPM. Un point sur les prévalences (française et mondiale) et sur les étiologies de ces pathologies est également proposé afin de permettre aux praticiens de répondre aux éventuelles interrogations des parents. Conclusion: La connaissance de ces différents éléments sur le diagnostic, la structure, les prévalences et les étiologies permettra à l'orthodontiste une meilleure collaboration avec le chirurgien-dentiste, mais également avec les parents afin d'assurer une prise en charge dentaire et orthodontique adéquate.

Insights into molar-incisor hypomineralisation in past populations: A call to anthropologists.

OBJECTIVE: Molar incisor hypomineralisation (MIH) is a developmental defect of enamel affecting the first permanent molars and often the incisors and affecting approximately 13% of the current population worldwide. Here, we aim to highlight potential differential diagnoses of MIH in archaeological collections (taphonomic discoloration, amelogenesis imperfecta, fluorosis, rachitic teeth, etc.). METHODS: Causative factors of dental discolourations are identified through a literature review. RESULTS: In an archaeological context, the sediments contained in the burial soil can lead to tooth discoloration. Taphonomic staining of the dentition may have a similar appearance to enamel hypomineralisation, and thus is a confounding factor that has the potential to cause miscalculation of the true prevalence of MIH within archaeological collections. Some rare medieval cases are reported in the modern literature but without microanalysis, misdiagnosis is possible. The aetiological factors of MIH are unknown but probably follow the multifactorial model involving systemic medical and genetic factors. CONCLUSIONS: Systematic detection and diagnosis of MIH during anthropological studies is therefore of great interest. SIGNIFICANCE: The hypotheses that only contemporary agents are causative factors of MIH could be refuted by the discovery of individuals living before medication or pollutants. The identification of MIH in a group of individuals also provides information regarding the health status of a population and reflects stress occurring during the period of mineralisation of the first permanent molars after secretion of the enamel matrix. LIMITATIONS: Taphonomic alterations of archaeological remains prevent MIH diagnosis. SUGGESTIONS FOR FUTURE RESEARCH: MIH diagnosis can be difficult in archaeological series and further non-destructive methods (microtomography, elemental analyses, etc.) are required.

Prevalence of taurodontism: meta-analysis in recent humans and evolutionary perspectives.

Taurodontism is a continuous anatomical variation of permanent and primary posterior teeth represented by an enlargement of the pulp cavity. A high prevalence of the trait is reported in Homo neanderthalensis remains. Exploring and refining epidemiology of taurodontism in actual populations could strengthen the hypothesis of a selective advantage for a high attrition diet (as heavy tooth wear in Homo sapiens evolution changed little until recently) or favour pleiotropic or genetic drift effects to explain the high frequency of the trait in Neandertal remains. Prevalence ranges between 0.1% and 48% in the literature. The aim of the present study is to assess the prevalence of taurodontism in recent populations by means of meta-analysis, that is, is the prevalence of taurodontism lower or higher in modern human living populations, where the selective advantages of high attrition diet are still expected? From 90 potentially eligible studies, 15 were included in the meta-analysis. Only cross-sectional studies were reported, and 14,771 participants were included. The meta-analyses were performed with a random model, calculating a weighted-mean prevalence of 11.8%. Gender was found to be unrelated to the prevalence of taurodontism (OR = 0.84 (95% CI 0.67-1.05), p > 0.05). Taurodontism occurs in approximately 11.8% of the living population. This result questions the status of taurodontism as a "typical trait" in Homo neanderthalensis and allows a possible common evolutionary mechanism in Homo sapiens and Homo neanderthalensis for the trait. Further studies should include more accurate and standardized methods to assess the condition.

Enhancing the learning of evolutionary anthropology skills by combining student-active teaching with actual and virtual immersion of Master's students in fieldwork, laboratory practice, and dissemination.

Higher education in evolutionary anthropology involves providing students with in-depth knowledge of biological and cultural heritage sites and collections that are frequently inaccessible. Indeed, most sites, fossils, and archaeological remains can be visited or manipulated only rarely and solely by specialists with extensive experience. Owing to the development of 3D and medical imaging techniques, this fragile heritage is now more widely accessible, and in a dynamic way. However, exclusive adoption of virtual teaching and learning has a negative impact on student engagement and, naturally, on exchanges with instructors, and thus cannot be used without some reservations. In the ITAP (Immersion dans les Terrains de l'Anthropologie biologique et de la Préhistoire) project of the higher education STEP (Soutien à la Transformation et à l'Expérimentation Pédagogiques) transformation program at the University of Bordeaux, we combine student-active teaching with Master's students fully immersed in ongoing fieldwork, laboratory study, and dissemination of research results in order to develop more individually shaped learning curricula and to foster both professional and new interdisciplinary skills. Here, we present examples of experiments conducted in the ITAP project using both authentic and virtual collections of archaeological, experimental, and reference materials that help to break down the barriers between research activities and higher education, as well as providing a more general appraisal of the appropriate use of virtual tools in higher education by combining them with real-life situations.

Investigating mitochondrial DNA relationships in Neolithic Western Europe through serial coalescent simulations.

Recent ancient DNA studies on European Neolithic human populations have provided persuasive evidence of a major migration of farmers originating from the Aegean, accompanied by sporadic hunter-gatherer admixture into early Neolithic populations, but increasing toward the Late Neolithic. In this context, ancient mitochondrial DNA data collected from the Neolithic necropolis of Gurgy (Paris Basin, France), the largest mitochondrial DNA sample obtained from a single archeological site for the Early/Middle Neolithic period, indicate little differentiation from farmers associated to both the Danubian and Mediterranean Neolithic migration routes, as well as from Western European hunter-gatherers. To test whether this pattern of differentiation could arise in a single unstructured population by genetic drift alone, we used serial coalescent simulations. We explore female effective population size parameter combinations at the time of the colonization of Europe 45000 years ago and the most recent of the Neolithic samples analyzed in this study 5900 years ago, and identify conditions under which population panmixia between hunter-gatherers/Early-Middle Neolithic farmers and Gurgy cannot be rejected. In relation to other studies on the current debate of the origins of Europeans, these results suggest increasing hunter-gatherer admixture into farmers' group migrating farther west in Europe.

Determination and validation of criteria to define hypercementosis in two medieval samples from France (Sains-en-Gohelle, AD 7th-17th century; Jau-Dignac-et-Loirac, AD 7th-8th century).

OBJECTIVE: The main aim of this article was to develop different visual criteria allowing for an objective definition of hypercementosis (cementum hyperplasia). This preliminary study must notably show how to better understand at a later stage the significance of its frequency as well as its aetiologies, especially in past populations. MATERIALS AND METHODS: we set up a study protocol (macroscopic and photographic observations) on material consisting of 2 medieval samples from France (1) Sains-en-Gohelle sample-SG (AD 7th-17th century; 407 individuals; 5756 teeth observed, 319 with hypercementosis) which was used to develop the different criteria for defining hypercementosis (2) Jau-Dignac-et-Loirac sample-JDL (AD 7th-8th century; 55 individuals; 709 teeth observed, 24 with hypercementosis) which was used to test the reproducibility of the criteria. RESULTS: From our observations we formulated different inclusion criteria with which to define hypercementosis objectively (k intraobserver≥0.96; k interobserver≥0.63). We were able to distinguish moderate (1m) and marked (1M) forms of diffuse hypercementosis, focal hypercementosis in the form of small knots (2m) or large nodules (2M), or excrescences in the form of ridges (3m) or spurs (3M). Different exclusion criteria were also determined. CONCLUSION: The definition that we propose in this study are based on various statistically validated inclusion and exclusion criteria. It is hoped that this will improve the significance of hypercementosis. More generally, this would also give a better understanding of the dynamics of cementum apposition.

Human tooth wear in the past and the present: tribological mechanisms, scoring systems, dental and skeletal compensations.

This review of human tooth wear describes the fundamental mechanisms underlying this process. Using the tribological approach they can be systematised and this in turn aids our understanding of them. In past populations wear was ubiquitous, intense, abrasive and physiological as it was related to their food and their technologies. In these populations, it affected the proximal surfaces, and the occlusal surfaces which modified the occlusal plane profoundly. To categorise this wear many different classification systems are used, from which we can determine diet, cultural changes and the age at death of individuals. They also illustrate the evolution of certain functional dental and skeletal compensations in the masticatory apparatus such as continuous dental eruption, mesial drift of the arches and incisor lingual tipping which can then be monitored. These physiological adaptations related mainly to function and ontogenesis can also be found in present-day populations where wear is moderate, although they are much less obtrusive. Apart from certain pathological cases associated with a specific parafunction, iatrogenic tooth brushing or an eating disorder and encouraged by an acid environment, they are the result of a physiological process that should not be halted. To ensure this, it is essential to prevent lesions related to tooth wear, to detect them early and establish a reliable diagnosis. Types of tooth wear that had remained unchanged since the origin of humanity have undergone profound changes in a very short space of time. Today's tribochemical pathological model has replaced the abrasive physiological model of the past.

Anatomical placement of the human eyeball in the orbit--validation using CT scans of living adults and prediction for facial approximation.

Accuracy of forensic facial approximation and superimposition techniques relies on the knowledge of anatomical correlations between soft and hard tissues. Recent studies by Stephan and collaborators (6,8,10) reviewed traditional guidelines leading to a wrong placement of the eyeball in the orbit. As those statements are based on a small cadaver sample, we propose a validation of these findings on a large database (n = 375) of living people. Computed tomography scans of known age and sex subjects were used to collect landmarks on three-dimensional surfaces and DICOM with TIVMI. Results confirmed a more superior and lateral position of the eyeball relatively to the orbital rims. Orbital height and breadth were used to compute regression formulae and proportional placement using percentages to find the most probable position of the eyeball in the orbit. A size-related sexual dimorphism was present but did not impact on the prediction accuracy.

Splenic infarction associated with a mobile aortic valve lesion: a case report and review of the literature.

The present report describes a 67-year-old woman with a mobile aortic valve lesion discovered by transesophageal echocardiography performed in the setting of abdominal pain. Definitive identification of the lesion was not possible by transesophageal echocardiography alone. Pathological examination of the excised lesion led to the diagnosis of papillary fibroelastoma (PFE). PFEs are rare benign tumours that primarily affect cardiac valves. Because left-sided PFEs are associated with a high risk of systemic embolization including cerebral ischemia and myocardial infarction, they require preventive surgical correction. The present case of PFE is reviewed for a better understanding of its pathology.