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The meaning of the shape of the frontal bone, facial retraction and prognathism for the degree of gracilisation of the supraorbital region in Homo sapiens
Morphological variations of the femoral head-neck junction in historical skeletal material
Background Poirier’s facet, Allen’s fossa and femoral plague are the main morphological variations of the femoral head-neck junction. The study aimed to answer questions about the association between the shape of the proximal end of the femoral bone and acetabulum in bones with head-neck junction changes and the differences in shape and size between joints with the above changes and joints without ones. Methods The analyses were performed on the computed tomography scans (CTs) of the 52 sets of bones (femur and pelvic bone) from the Polish skeletal material dated to the 14th–19th centuries. Based on CTs, three-dimensional models of the femurs and pelvic bones were created and then analysed using linear measurements and a geometric morphometric approach. Analysis of variance (ANOVA) was calculated to analyse differences in size; in turn, canonical variate analysis (CVA) was calculated to investigate changes in shape between bones with femoral-neck changes and bones without ones. Results According to the CVA, there were no significant differences in shape between bones with Allen’s fossa, femoral plaque, or Porier’s facet and hip joints without any observable changes (p > 0.05). Bones with observable Allen’s fossa, femoral plaque, Porier’s facet and hip joints without changes showed similar variations in femoral head shape. The difference was in the femoral head height between bones femoral plaque and bones with Allen’s fossa (p = 0.047, mean difference = 3.78 mm). Acetabula in the sets of bones without head-neck junction changes showed slightly lower shape variation than acetabulum in the sets of bones with changes. In joints with head-neck junction changes, a more indented antero-posterior part of the lunate surface and indented inferior edge along its entire length were observed. Conclusions Geometric morphometrics and measurements showed similarities in the shape of the joints with and without changes in head-neck junction region. This may indicate that morphological changes in the femoral head-neck junction do not significantly affect the morphology of the femur and acetabulum. However, understanding the role and efficiency of this influence needs further studies.
Zwyczajna w swojej niezwyczajności? Analiza budowy wewnętrznej czaszki "gigantki" z Ostrowa Lednickiego
Trunk climbing among ground-dwelling European amphibians – first observation from Poland
Most European amphibian species are considered land-dwelling, associated with moving along the ground and as poor climbers. However, more recent research indicates that non-arboreal amphibians use nesting boxes and tree hollows in Central and Western Europe. This study describes the first observation of tree climbing by the common toad Bufo bufo (Linnaeus, 1758) and common frog Rana temporaria Linnaeus, 1758 in Poland. While conducting a night survey of newt mortality in the ‘Traszki Ratajskie’ protected area in an urban park in the city of Poznań, Poland, we detected the unexpected use of trees by two species of amphibians. In June 2020, we observed cases of Bufo bufo and Rana temporaria foraging on and using arboreal ambush sites. The toads were found at an average height of 124 cm above the ground, and the frogs at 35 cm, on the tree trunks and branches of two willows (Salix cfr. alba L.) and a dead silver birch specimen (Betula pendula L.). The willows had an extensive multi-stem structure, and exhibited signs of maturity and ageing (hollow-bearing trees with open cavities and crevices). This is the first observation of arboreal behaviour in B. bufo and R. temporaria in Poland. The climbing behaviour and use of tree sites were likely linked to the search for a humid shelter provided by the interior of the ageing trees, as well as to the foraging behaviour that we observed. Trees exhibiting signs of maturity usually have complex structures, and seem particularly important for amphibians during periods of drought, as both a suitable shelter and an area from which to ambush prey. We recommend focusing greater attention on the protection of mature, ageing trees, especially Salix spp. within a terrestrial buffer zone of at least 250 metres from ponds, as these are poorly researched components within amphibian habitats. This type of resource may be essential for long-term amphibian conservation due to site fidelity and the limited number of shelters in human-altered landscapes. The recently adopted EU Nature Restoration Law presents an opportunity to develop good practices in this area, particularly urban tree planting and habitat management.
Publisher Correction: Variation in cross-sectional indicator of femoral robusticity in Homo sapiens and Neandertals
Abstract Variations in the cross-sectional properties of long bones are used to reconstruct the activity of human groups and differences in their respective habitual behaviors. Knowledge of what factors influence bone structure in Homo sapiens and Neandertals is still insufficient thus, this study investigated which biological and environmental variables influence variations in the femoral robusticity indicator of these two species. The sample consisted of 13 adult Neandertals from the Middle Paleolithic and 1959 adult individuals of H. sapiens ranging chronologically from the Upper Paleolithic to recent times. The femoral biomechanical properties were derived from the European data set, the subject literature, and new CT scans. The material was tested using a Mantel test and statistical models. In the models, the polar moment of area (J) was the dependent variable; sex, age, chronological period, type of lifestyle, percentage of the cortical area (%CA), the ratio of second moment areas of inertia about the X and Y axes (Ix/Iy), and maximum slope of the terrain were independent covariates. The Mantel tests revealed spatial autocorrelation of the femoral index in H. sapiens but not in Neandertals. A generalized additive mixed model showed that sex, %CA, Ix/Iy, chronological period, and terrain significantly influenced variation in the robusticity indicator of H. sapiens femora. A linear mixed model revealed that none of the analyzed variables correlated with the femoral robusticity indicator of Neandertals. We did not confirm that the gradual decline in the femoral robusticity indicator of H. sapiens from the Middle Paleolithic to recent times is related to the type of lifestyle; however, it may be associated with lower levels of mechanical loading during adolescence. The lack of correlation between the analysed variables and the indicator of femoral robusticity in Neandertals may suggest that they needed a different level of mechanical stimulus to produce a morphological response in the long bone than H. sapiens .
Changes in plasticity of the pelvic girdle from infancy to late adulthood in Homo sapiens
AbstractPrevious research on the effects of body mass on the pelvic girdle focused mostly on adult females and males. Because the ontogenetic plasticity level in the pelvis remains largely unknown, this study investigated how the association between body mass index (BMI) and pelvic shape changes during development. It also assessed how the large variation in pelvic shape could be explained by the number of live births in females. Data included CT scans of 308 humans from infancy to late adulthood with known age, sex, body mass, body stature, and the number of live births (for adult females). 3D reconstruction and geometric morphometrics was used to analyze pelvic shape. Multivariate regression showed a significant association between BMI and pelvic shape in young females and old males. The association between the number of live births and pelvic shape in females was not significant. Less plasticity in pelvic shape in adult females than during puberty, perhaps reflects adaptation to support the abdominopelvic organs and the fetus during pregnancy. Non-significant susceptibility to BMI in young males may reflect bone maturation accelerated by excessive body mass. Hormonal secretion and biomechanical loading associated with pregnancy may not have a long-term effect on the pelvic morphology of females.
Morphology of mandibles of clown beetles (Coleoptera: Histeridae): hidden diversity, sexual dimorphism, and implications for prey range
Abstract Clown beetles (Histeridae) are stable components of carrion communities, but their prey range is poorly recognised. An indirect way to deduce species’ diet is to study the functional morphology of their mandibles. The use of a multimodal approach in the study of Margarinotus brunneus, Margarinotus striola succicola, Saprinus semistriatus, and Saprinus planiusculus revealed a hidden morphological diversity in their mandibles. Geometric morphometric analysis showed inter- and sex-specific differences in their shape. Synchrotron X-ray microtomography revealed variability in musculature between genera and the presence of a joint-like structure at the basal margins in the Saprinus species. Scanning electron microscopy showed variation in the surface of inner margins. Traditional morphometrics revealed differences in mandibular arc according to beetle species, sex, and left and right body sides. All species retained a roughly 17° asymmetry, with the right mandible always having the higher arc. We conclude that Saprinus species are adapted for cutting and puncturing soft-bodied prey, whereas Margarinotus beetles also feed on hard-bodied prey. Future studies should consider our findings for better planning of prey-choice experiments. Emphasis should be placed on recognising whether subtle differences in mandible shape involve differences in diets. This will be critical to determine the role of species in carrion ecosystems.
Variation in cross-sectional indicator of femoral robusticity in Homo sapiens and Neandertals
Abstract Variations in the cross-sectional properties of long bones are used to reconstruct the activity of human groups and differences in their respective habitual behaviors. Knowledge of what factors influence bone structure in Homo sapiens and Neandertals is still insufficient thus, this study investigated which biological and environmental variables influence variations in the femoral robusticity indicator of these two species. The sample consisted of 13 adult Neandertals from the Middle Paleolithic and 1959 adult individuals of H. sapiens ranging chronologically from the Upper Paleolithic to recent times. The femoral biomechanical properties were derived from the European data set, the subject literature, and new CT scans. The material was tested using a Mantel test and statistical models. In the models, the polar moment of area (J) was the dependent variable; sex, age, chronological period, type of lifestyle, percentage of the cortical area (%CA), the ratio of second moment areas of inertia about the X and Y axes (Ix/Iy), and maximum slope of the terrain were independent covariates. The Mantel tests revealed spatial autocorrelation of the femoral index in H. sapiens but not in Neandertals. A generalized additive mixed model showed that sex, %CA, Ix/Iy, chronological period, and terrain significantly influenced variation in the robusticity indicator of H. sapiens femora. A linear mixed model revealed that none of the analyzed variables correlated with the femoral robusticity indicator of Neandertals. We did not confirm that the gradual decline in the femoral robusticity indicator of H. sapiens from the Middle Paleolithic to recent times is related to the type of lifestyle; however, it may be associated with lower levels of mechanical loading during adolescence. The lack of correlation between the analysed variables and the indicator of femoral robusticity in Neandertals may suggest that they needed a different level of mechanical stimulus to produce a morphological response in the long bone than H. sapiens .
Brain vs. endocast: Does size differ? A unique experiment based on a cohort of 75 volunteers
AbstractResearch on brain evolution centres mainly on internal mouldings of the skull, known as endocasts; however, the relationship between the size and asymmetry of the brain and endocasts has been poorly investigated in humans. Therefore, the main objective of this study was to investigate whether endocasts can be reliable indicators of brain size and asymmetry. Magnetic Resonance Imaging (MRI) of 75 participants was used to calculate the volume and surface area of the brain, the endocast, and their respective hemispheres. Two asymmetry indices (i.e. directional and absolute asymmetry) were used to assess the differences in volume and surface area between the sides of the brain and endocast. The Pearson correlation coefficient was calculated to assess the relationships between the parameters, and a Monte Carlo simulation for linear regression was performed to generate prediction equations for brain volume. The relationships between the level and direction of asymmetry indices were investigated using the Pearson correlation and McNemar's test, respectively. All correlations were statistically significant; however, correlation coefficients between volumes were stronger (0.894–0.931) than between volumes and surface areas (0.783–0.834). Brain volume can be predicted with high accuracy (ranging between 0.80 and 0.87) using the endocast total volume or the volume of one of the sides. The associations between the levels of asymmetry indices of the brain and endocast were non‐significant; however, the McNemar's test indicated that endocasts show the same left‐ or right‐biased asymmetry as the brain. This was the first study conducted on a large sample of brain and endocast data from the same individuals. The results demonstrated that brain volume can be accurately reconstructed using the volume of the endocast or one of its sides. This finding is especially important in the context of reconstructing fossil skulls, which are usually fragmented. Conversely, the asymmetry levels of endocast parameters are not reliable indicators of the actual level of brain volume asymmetry. Future research on fossils should focus on endocast asymmetry direction (left‐ or right‐biased) as this closely corresponds with brain lateralisation.
Frontal sinuses and human evolution
The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species’ holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus . Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species.