Investigating the impact of captivity and domestication on limb bone cortical morphology: an experimental approach using a wild boar model

The lack of bone morphological markers associated with the human control of wild animals has prevented the documentation of incipient animal domestication in archaeology. Here, we assess whether direct environmental changes (i.e. mobility reduction) could immediately affect ontogenetic changes in long bone structure, providing a skeletal marker of early domestication. We relied on a wild boar experimental model, analysing 24 wild-born specimens raised in captivity from 6 months to 2 years old. The shaft cortical thickness of their humerus was measured using a 3D morphometric mapping approach and compared with 23 free-ranging wild boars and 22 pigs from different breeds, taking into account sex, mass and muscle force differences. In wild boars we found that captivity induced an increase in cortical bone volume and muscle force, and a topographic change of cortical thickness associated with muscular expression along a phenotypic trajectory that differed from the divergence induced by selective breeding. These results provide an experimental proof of concept that changes in locomotor behaviour and selective breeding might be inferred from long bones morphology in the fossil and archaeological record. These trends need to be explored in the archaeological record and further studies are required to explore the developmental changes behind these plastic responses

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Cranial muscle architecture in wild boar : does captivity drive ontogenetic trajectories?

Abstract: The jaw system in mammals is complex and different muscle morphotypes have been documented. Pigs are an interesting group of animals as they are omnivorous and have a bunodont crushing dentition. Moreover, they have interacted with humans for over 10,000 years and grow nearly two orders of magnitude in size. Despite being a model system for studies on cranial form and function, data on the growth of the jaw adductor muscles are scant. Moreover, whether captivity impacts the growth and architecture of the jaw adductors remains unknown. Based on dissection data of the jaw adductors of 45 animals ranging from less than 1 kg to almost 100 kg, we show that muscle masses, muscle fiber lengths, and cross-sectional areas scale as predicted for geometrically similar systems or with slight negative allometry. Only the fiber length of the lateral pterygoid muscle grew with slight positive allometry. Animals raised in captivity in stalls or in an enclosure were overall very similar to wild animals. However, some muscles were larger in captive animals. Interestingly, variation in bite force in captive animals was well predicted by the variation in the size of the superficial masseter muscle relative to the overall jaw adductor mass. We show that muscle masses, muscle fiber lengths, and cross-sectional areas in wild boar scale as predicted for geometrically similar systems or with slight negative allometry. Animals raised in captivity in stalls or in an enclosure were overall very similar to wild animals.imag

Impact des activités locomotrices sur la biomécanique du fémur : étude ontogénétique du babouin olive

International audienc

Do femoral biomechanical properties follow locomotor changes in primates? An ontogenetic study of olive baboons ( Papio anubis )

International audienc

: Do femoral biomechanics reflect locomotor behaviors? Study of the structural properties of the femoral diaphysis among catarrhines.

Durant la locomotion, la diaphyse fémorale subit des charges mécaniques impactant son organisation structurelle. L’étude de la structure corticale des vestiges fossiles représente donc un potentiel accès à la reconstruction de l’environnement mécanique des hominines fossiles, et donc à leur locomotion. Cependant, peu d’études ont abordé expérimentalement cette question et d’autres facteurs tels que l’âge, la masse et le niveau d’activité viennent complexifier cette relation entre structure fémoro-diaphysaire et locomotion. Une première étude menée sur un échantillon ontogénétique de babouins olive vivant à la Station de Primatologie du CNRS (UAR 846), a démontré une faible correspondance entre les variations de l’organisation du tissu cortical de la diaphyse fémorale et celles du répertoire posturo-locomoteur au cours de l’âge. Pour poursuivre l’étude de cette relation entre les propriétés biomécaniques de la diaphyse fémorale et la locomotion, nous avons analysé et comparé les cartographies d’épaisseur corticale et des paramètres de géométrie de section sur plus de 50 fémurs de primates catarhiniens adultes (genres Homo, Gorilla, Pan, Hylobates, Papio, Macaca), de morphologies et de répertoires posturo-locomoteurs différents.Nos résultats montrent l’existence de schémas biomécaniques variés, montrant une certaine proximité entre grands singes africains et hylobatidés, dont les babouins et surtout les humains se distinguent. Les propriétés biomécaniques de la diaphyse fémorale permettent de distinguer des grands groupes, mais pas de caractériser précisément les répertoires posturo-locomoteurs les plus diversifiés.Pour permettre une différenciation plus fine des répertoires posturo-locomoteurs complexes, exploitable dans une perspective paléoanthropologique, nous proposons l’intégration de l’approche biomécanique à de la morphométrie géométrique

Phylogenetic and biomechanical influences in the structural pattern of the femoral diaphysis among catarrhines

International audienceThe interpretation of hominin locomotor behaviors, which is largely based on actualism, implies a clear understanding of form-function relationship between the biomechanics of the skeleton and the locomotor behaviors of extant primates. In this study, we tested this relationship by measuring the structural properties of 127 femoral diaphyses from six genera and 10 species of catarrhine primates whose locomotor behaviors are well documented. The structural properties were assessed on the entire diaphysis via cross-sectional geometry properties including relative cortical area (%CA) and cross-sectional bending rigidity and shape (Ix/Iy and Imax/Imin), as well as the pattern of overall cortical bone distribution (cortical thickness maps). Concerning cross-sectional properties, our results highlight marked differences in CSG along the femoral diaphysis of locomotor-related groups such as knuckle-walker African apes and quadrupedal cercopithecoids. Humans seem to be distinctive in their anteroposterior bending rigidity, especially at midshaft, while brachiator hylobatids differ very little from all other groups. Concerning overall cortical bone distribution, humans differ from non-human primates. In the latter, a hominoid-cercopithecoid partition supports previously reported influence of phylogeny rather than locomotor behaviors in shaping the structural properties of the femoral diaphysis. Caution is therefore needed when inferring locomotor behavior in fossils solely based on femoral structural properties.L'interprétation des comportements locomoteurs des hominines, largement basée sur le principe d’actualisme, implique une compréhension claire de la relation forme-fonction existant entre la biomécanique du squelette et les comportements locomoteurs des primates actuels. Dans cette étude, nous avons testé cette relation en mesurant les propriétés endostructurales de 127 diaphyses fémorales provenant de six genres et de dix espèces de primates catarrhiniens, dont les comportements locomoteurs sont documentés. Les propriétés endostructurales ont été mesurées sur la totalité de la diaphyse par le biais des paramètres de géométrie de section, notamment l’aire corticale relative (%CA), la rigidité à la flexion et la forme des sections (Ix/Iy et Imax/Imin), ainsi que le modèle de distribution de l'os cortical (cartographies d'épaisseur corticale). Concernant les paramètres de géométrie de section de la diaphyse fémorale, nos résultats mettent en évidence des différences marquées entre des groupes dont la locomotion est proche, tels que les grands-singes africains knuckle-walkers et les cercopithécoïdes quadrupèdes. Les humains semblent se distinguer par une rigidité à la flexion orientée antéropostérieurement, en particulier à mi-diaphyse, tandis que les hylobatidés brachiateurs diffèrent très peu des autres groupes. Concernant le modèle de distribution de l'os cortical, les humains diffèrent des primates non-humains. Chez ces derniers, une distinction entre hominoïdes et cercopithécoïdes confirme une influence de la phylogénie plutôt que des comportements locomoteurs dans la modulation des propriétés endostructurales de la diaphyse fémorale, comme rapporté par de précédents travaux. Il convient donc d'être prudent lorsque des comportements locomoteurs de fossiles sont déduits uniquement sur la base des propriétés endostructurales du fémur

Convergence in the functional properties of forelimb muscles in carnivorans : adaptations to an arboreal lifestyle?

The arboreal environment is complex and irregular and imposes significant constraints on the locomotor ability of vertebrates, resulting in morphological adaptations. Carnivorans are of particular interest because they radiated several times independently into the arboreal milieu, leading to convergence in long bone anatomy. We investigated whether the forelimb muscles show differences in arboreal vs. terrestrial species and tested for convergence in muscle architecture. To do so, we studied the forelimb muscles in 17 species of carnivorans with different locomotor modes (arboreal and terrestrial). Our results showed that the forelimb musculature evolved in a convergent manner in arboreal species, resulting in more forceful and heavier wrist rotators and elbow flexors, even when accounting for phylogeny. This suggests that selective forces imposed by the environment drive the evolution of the muscular system towards a convergent phenotype that provides a functional advantage for locomotion in the complex three-dimensional arboreal habitat

The Doublesex Homolog Dmrt5 is Required for the Development of the Caudomedial Cerebral Cortex in Mammals.

Regional patterning of the cerebral cortex is initiated by morphogens secreted by patterning centers that establish graded expression of transcription factors within cortical progenitors. Here, we show that Dmrt5 is expressed in cortical progenitors in a high-caudomedial to low-rostrolateral gradient. In its absence, the cortex is strongly reduced and exhibits severe abnormalities, including agenesis of the hippocampus and choroid plexus and defects in commissural and thalamocortical tracts. Loss of Dmrt5 results in decreased Wnt and Bmp in one of the major telencephalic patterning centers, the dorsomedial telencephalon, and in a reduction of Cajal-Retzius cells. Expression of the dorsal midline signaling center-dependent transcription factors is downregulated, including Emx2, which promotes caudomedial fates, while the rostral determinant Pax6, which is inhibited by midline signals, is upregulated. Consistently, Dmrt5(-/-) brains exhibit patterning defects with a dramatic reduction of the caudomedial cortex. Dmrt5 is increased upon the activation of Wnt signaling and downregulated in Gli3(xt/xt) mutants. We conclude that Dmrt5 is a novel Wnt-dependent transcription factor required for early cortical development and that it may regulate initial cortical patterning by promoting dorsal midline signaling center formation and thereby helping to establish the graded expression of the other transcription regulators of cortical identity.JOURNAL ARTICLESCOPUS: ar.jinfo:eu-repo/semantics/publishe