Identification of functionally-related adaptations in the trabecular network of the proximal femur and tibia of a bipedally-trained Japanese macaque

The axial and appendicular skeleton of Japanese macaques (Macacca fuscata) trained to adopt ipedal posture and locomotion display a number of functionally-related external and internal macro- and micro-morphological changes, including site-specific cortical and trabecular bone adaptations. In this study we use high-resolution microtomography scanning to analyse the 3D distribution of trabecular architecture of the proximal femur and proximal tibia of Sansuke, a male individual trained in bipedal performances for eight years, as well as five wild individuals. The distribution and architecture of trabecular bone in the femoral head of Sansuke is distinct from that found in wild M. fuscata individuals, with a unique bone reinforcement around the region of the fovea capitis. Conversely, wild individuals exhibit two pillar-like, high-density structures (converging in an inverted cone) that reach distinct regions of the posterior and anterior surfaces of the femoral head. For Sansuke’s proximal tibia, contrary to previous observations from the cortico-trabecular complex distribution at the plateau, our results do not show a more asymmetric distribution between medial and lateral condyles with a medial reinforcement. Additionally, relative bone volume in this region is not significantly higher in Sansuke. However, we observed a slightly more medially placed bone reinforcement in the lateral condyle compared to the wild individuals as well as a slightly higher trabecular bone anisotropy in the medial than in the lateral condyle not observed in the wild individuals. These analyses provide new evidence about the nature and extent of functionally-related adaptive arrangements of the trabecular network at the coxofemoral and the knee joints in individuals recurrently experiencing atypical load

Is the deciduous/permanent molar enamel thickness ratio a taxon-specific indicator in extant and extinct hominids?

In Primates, enamel thickness variation stems from an evolutionary interplay between functional/adaptive constraints (ecology) and the strict control mechanisms of the morphogenetic program. Most studies on primate enamel thickness have primarily considered the permanent teeth, while the extent of covariation in tooth enamel thickness distribution between deciduous and permanent counterparts remains poorly investigated. In this test study on nine extant and fossil hominids we investigated the degree of covariation in enamel proportions between 25 pairs of mandibular dm2 and M1 by a so-called “lateral enamel thickness diphyodontic index”. The results did not provide an unambiguous picture, but rather suggest complex patterns likely resulting from the influence of many interactive factors. Future research should test the congruence of the “diphyodontic signal” between the anterior and the postcanine dentition, as well as between enamel and the enamel-dentine junction topography

A Neanderthal from the Central Western Zagros, Iran. Structural reassessment of the Wezmeh 1 maxillary premolar

Wezmeh Cave, in the Kermanshah region of Central Western Zagros, Iran, produced a Late Pleistocene faunal assemblage rich in carnivorans along with a human right maxillary premolar, Wezmeh 1, an unerupted tooth from an 8 ± 2 year-old individual. Uranium-series analyses of the fauna by alpha spectrometry provided age estimates between 70 and 11 ka. Crown dimensions place the tooth specimen at the upper limits of Late Pleistocene human ranges of variation. Wezmeh 1 metameric position (most likely a P3) remains uncertain and only its surficial morphology has been described so far. Accordingly, we used micro-focus X-ray tomography (12.5 μm isotropic voxel size) to reassess the metameric position and taxonomic attribution of this specimen. We investigated its endostructural features and quantified crown tissue proportions. Topographic maps of enamel thickness (ET) distribution were also generated, and semilandmark-based geometric morphometric analyses of the enamel-dentine junction (EDJ) were performed. We compared Wezmeh 1 with unworn/slightly-moderately worn P3 and P4 of European Neanderthals, Middle Paleolithic modern humans from Qafzeh, an Upper Paleolithic premolar, and Holocene humans. The results confirm that Wezmeh 1 represents a P3. Based on its internal conformation and especially EDJ shape, Wezmeh 1 aligns closely with Neanderthals and is distinct from the fossil and extant modern human pattern of our comparative samples. Wezmeh 1 is thus the first direct evidence of Neanderthal presence on the western margin of the Iranian Plateau

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Targeting the RNA m⁶A reader YTHDF2 selectively compromises cancer stem cells in acute myeloid leukemia

International audienc

Is the deciduous/permanent molar enamel thickness ratio a taxon-specific indicator in extant and extinct hominids?

In Primates, enamel thickness variation stems from an evolutionary interplay between functional/adaptive constraints (ecology) and the strict control mechanisms of the morphogenetic program. Most studies on primate enamel thickness have primarily considered the permanent teeth, while the extent of covariation in tooth enamel thickness distribution between deciduous and permanent counterparts remains poorly investigated. In this test study on nine extant and fossil hominids we investigated the degree of covariation in enamel proportions between 25 pairs of mandibular dm2 and M1 by a so-called “lateral enamel thickness diphyodontic index”. The results did not provide an unambiguous picture, but rather suggest complex patterns likely resulting from the influence of many interactive factors. Future research should test the congruence of the “diphyodontic signal” between the anterior and the postcanine dentition, as well as between enamel and the enamel-dentine junction topography

Relations entre comportement locomoteur et variation cortico-trabéculaire du plateau tibial chez les primates (analyse quantitative non invasive à haute résolution (SR- CT) et applications au registre fossile)

En se basant sur les relations biodynamiques entre fonction et organisation structurale osseuse, des différences dans l'agencement morpho-architectural du plateau tibial sont attendues chez les Primates en raison de la variété des comportements posturaux et locomoteurs. Cependant, la variation de l'endo-structure de cette articulation clé reste peu explorée chez les Mammifères dans une perspective comparative et évolutive. Les objectifs de ce travail sont (i) de détailler et de mesurer, à travers l'imagerie à haute résolution (microtomographie par rayonnement synchrotron SR- CT), la variation topographique du "complexe cortico-trabéculaire" du tibia proximal chez les Primates actuels et (ii) d'évaluer les potentialités de cette approche pour la reconstruction du comportement locomoteur des formes fossiles. L'échantillon analysé consiste en 23 tibias représentant 12 taxons catarrhiniens, Homo inclus. Des cas pathologiques et anormaux (dont celui du macaque japonais "bipède") et des Mammifères non primates ont été également considérés. L'analyse quantitative comparative, basée sur la modélisation numérique tridimensionnelle, utilise des techniques issues de la géostatistique. Des modèles différenciés dans la distribution et dissipation des charges à travers la surface articulaire du tibia ont été mis en évidence en fonction du régime locomoteur (bipédie, knuckle-walking, brachiation, quadrupédies terrestre et arboricole); les cas pathologiques et anormaux se distinguent de la variation "normale". La découverte d'une signature structurale du tibia proximal liée aux dynamiques posturales et locomotrices ouvre, malgré des problèmes méthodologiques, de nouvelles perspectives dans les recherches paléobiomécaniques. Le tibia néanderthalien La Ferrassie 2, un des 13 hominoïdes et homininés fossiles également examinés dans cette étude (Proconsul, Australopithecus, Paranthropus, Homo), montre des singularités morpho-architecturales par rapport à la condition humaine moderne.According to the established relationships between biomechanical function and bone structural variation, deep locomotion-related differences in the inner organization of the tibial plateau are expected among the Primates, because of their variety of postural and locomotory behaviours. Nonetheless, the endostructural variation of this key joint remains poorly investigated among the Mammals in a comparative and evolutionary perspective. The goals of this study are (i) to detail and to measure, by means of high-resolution imaging (SR- CT synchrotron radiation microtomography), the topographic variation of the "cortico-trabecular complex" at the proximal tibia in extant Primates, and (ii) to explore the potentialities of this approach as a tool in reconstructing fossil locomotory behaviours. The investigated sample consists of 23 tibias from 12 catarrhine taxa, including Homo. A number of pathological and abnormal cases (including a bipedal-trained Japanese macaque) and of nonprimate Mammals have been also considered. The quantitative analysis, based on tridimensional virtual modelling, utilizes geostatistical methods. Different patterns of load distribution and dissipation at the tibial articular surface have been found in relation to the locomotory modes (bipedalism, knuckle-walking, brachiation, terrestrial and arboreal quadrupedalism); the pathological and abnormal cases are distinct from the "normal" variation. The finding of a locomotion-related structural signature at the proximal tibia discloses, despite some methodological problems, new research perspectives in paleobiomechanics. Among the 13 fossil hominoid and hominin specimens additionally considered in this study (Proconsul, Australopithecus, Paranthropus, Homo), the La Ferrassie 2 Neanderthal tibia shows a number of morpho-architectural features distinguished from the extant human condition.LYON1 - UFR Sciences de la terre (692662208) / SudocPOITIERS-BU Sciences (861942102) / SudocSudocFranceF

Endostructural characterization of the H. heidelbergensis dental remains from the early Middle Pleistocene site of Tighenif, Algeria

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Caractérisation de l’endostructure des restes dentaires de <i>H. heidelbergensis</i> du site pléistocène moyen initial de Tighenif, Algérie

L’assemblage humain fossile du site pléistocène initial de Tighenif, en Algérie, compte vraisemblablement parmi les premiers représentants du morphe Homo heidelbergensis. Une précédente étude de trois molaires déciduales de cet assemblage a révélé une signature structurale interne (proportions des tissus de la couronne et topographie de l’épaisseur de l’émail) approchant le schéma humain moderne. En utilisant des techniques avancées d’imagerie virtuelle et d’analyse quantitative 3D basées sur la microtomographie, nous étendons ici de manière significative le registre actuellement disponible à 22 dents permanentes, principalement de la denture mandibulaire, et fournissons les premières descriptions détaillées de la condition structurale caractérisant cette population Nord-Africaine, autour de la limite Pléistocène inférieur-moyen. Malgré un certain degré de variation individuelle, les dents de Tighenif montrent un patron structural combinant des caractéristiques primitives, dérivées et uniques. Les molaires inférieures dévoilent au niveau de la jonction émail-dentine un ensemble de traits non métriques plus fréquemment trouvés chez les humains modernes que chez les Néandertaliens, mais aussi un mélange de caractéristiques semblables soit à celles des Néandertaliens, soit à celles des humains modernes en termes de conformation structurale et de proportions des tissus. Elles présentent aussi des cavités pulpaires volumineuses, avec une bifurcation radiculaire assez élevée et des canaux pulpaires bien séparés, s’approchant plus particulièrement de la condition rapportée pour des Atériens du Pléistocène supérieur.The early Middle Pleistocene human fossil assemblage from Tighenif, Algeria, likely samples some among the earliest representatives of the Homo heidelbergensis morph. A previous study of three deciduous molars from this assemblage revealed an inner structural signature (crown tissue proportions and enamel thickness topography) roughly approximating the modern human figures. By using advanced techniques of microtomographic-based 3D virtual imaging and quantitative analysis, we significantly extend here the currently available record to 22 permanent teeth, mostly from the mandibular dentition, and provide the first detailed description of the structural condition characterizing this North African deme near the Lower-Middle Pleistocene boundary. Together with a certain degree of individual variation, the teeth of Tighenif exhibit a structural pattern combining primitive, derived, and unique features. The lower molars display a set of enamel-dentine junction nonmetric traits more frequently found in recent humans than in Neanderthals, but also a blend of Neanderthal- and modern-like characteristics in terms of structural conformation and crown tissue proportions. They also exhibit relatively large pulp cavities, with a rather high root bifurcation and well-separated pulp canals, a pattern more closely approximating the condition reported for Late Pleistocene Aterians.</p

Les plus anciens restes d’un fruit de &lt;i&gt;Citrus&lt;/i&gt; dans un contexte archéologique de l’Ouest de la Méditerranée ? Une révision basée sur la microtomographie

La découverte de restes carbonisés d’un fruit de type Citrus dans un dépôt votif du début du VIe siècle av. J.C. dans un site archéologique d’Ischia, l’île des premières colonies grecques du Sud de l’Italie, a relancé la question de la diffusion de Citrus dans l’Ouest de la Méditerranée au cours de l’Antiquité. Nous avons utilisé la microtomographie (SR-μCT et μCT) pour caractériser la structure interne du spécimen archéologique (SDC-mr.1a+b). Notre analyse comparative à haute définition, qui prend en considération un Citrus actuel carbonisé, une corme (Sorbus domestica) et une pomme sauvage (Malus type sylvestris) séchées, ne confirme pas l’attribution taxonomique originale (Coubray, 1996).The discovery of the carbonized remains of a Citrus-like fruit in a funerary offering deposit dated back to the beginning of the 6th century BC during archaeological work run at Ischia, the island which hosted one among the earliest Greek colonies in southern Italy, has relaunched the question of the spread of Citrus through western Mediterranean during Classical Antiquity. Here we apply microtomography (SR-μCT and μCT) to investigate the inner structure of the archaeological specimen (SDC-mr.1a+b). Our high-resolution comparative analysis, which also considered one carbonized modern Citrus and a dried modern Sorbus domestica (true service tree) and Malus type sylvestris (wild apple), does not support the original taxonomic attribution (Coubray, 1996).</p