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Midfacial morphology varies between hominoids, in particular between great apes and humans for which the face is small and retracted. The underlying developmental processes for these morphological differences are still largely unknown. Here, we investigate the cellular mechanism of maxillary development (bone modelling, BM), and how potential changes in this process may have shaped facial evolution. We analysed cross-sectional developmental series of gibbons, orangutans, gorillas, chimpanzees and present-day humans ( n = 183). Individuals were organized into five age groups according to their dental development. To visualize each species's BM pattern and corresponding morphology during ontogeny, maps based on microscopic data were mapped onto species-specific age group average shapes obtained using geometric morphometrics. The amount of bone resorption was quantified and compared between species. Great apes share a highly similar BM pattern, whereas gibbons have a distinctive resorption pattern. This suggests a change in cellular activity on the hominid branch. Humans possess most of the great ape pattern, but bone resorption is high in the canine area from birth on, suggesting a key role of canine reduction in facial evolution. We also observed that humans have high levels of bone resorption during childhood, a feature not shared with other apes.

Self-agency is a crucial aspect of self-awareness. It is underresearched given the phenomenon's subjectivity and difficulty of study. It is particularly underresearched comparatively, given that animals cannot receive agency instructions or make agency declarations. Accordingly, we developed a distinctively new self-agency paradigm. Humans and rhesus macaques learned event categories differentiated by whether the participant's volitional response controlled a screen launch. They learned by trial and error after minimal instructions with no agency orientation (humans) or no instructions (monkeys). After learning, humans' verbalized category descriptions were coded for self-agency attributions. Across three experiments, humans' agency attributions qualitatively improved discrimination performance-participants not invoking self-agency rarely exceeded chance performance. It also produced a diagnostic latency profile: classification accuracy depended heavily on the temporal relationship between the button-press and the launch, but only for those invoking agency . In our last experiment, monkeys performed the launch task. Their performance and latency profiles mirrored that of humans. Thus, self-agency can be self-discovered as a frame organizing discrimination. And it may be used as a discrimination cue by some nonhuman animals as well. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Heavy goods vehicle (HGV) driving is recognised as a highly hazardous occupation due to the long periods of sedentary behaviour, low levels of physical activity and unhealthy food options when working. These risk factors combine with shift work and concomitant irregular sleep patterns to increase the prevalence of fatigue. Fatigue is closely linked with stress and, subsequently, poor physiological and psychological health. In parallel, a wealth of evidence has demonstrated the health and wellbeing benefits of spending time in nature. Here, we sought to examine whether spending time in nature was associated with lower levels of fatigue, anxiety and depression in HGV drivers. 89 long-distance drivers (98.9% male, mean ± SD age: 51.0 ± 9 years, body mass index: 29.8 ± 4.7 kg/m 2 ) participating in a wider health promotion programme reported time spent in nature (during and before the Covid-19 pandemic) and symptoms of occupational fatigue, depression and anxiety. After controlling for covariates, truck drivers who visited nature at least once a week exhibited 16% less chronic fatigue prior to the pandemic, and 23% less chronic fatigue and 20% less acute fatigue during the pandemic. No significant differences were observed for either anxiety or depression. As fatigue has a range of physical and mental health sequelae, we propose that increased exposure to natural settings may make a valuable contribution to interventions to promote the health and wellbeing of this underserved group.

Objectives: Variation in trabecular and cortical bone properties is often used to infer habitual behavior in the past. However, the structures of both types of bone are rarely considered together and may even contradict each other in functional interpretations. We examine trabecular and cortical bone properties in various athletes and sedentary controls to clarify the associations between combinations of cortical and trabecular bone properties and various loading modalities., Materials and Methods: We compare trabecular and cortical bone properties using peripheral quantitative computed tomography scans of the tibia between groups of 83 male athletes (running, hockey, swimming, cricket) and sedentary controls using Bayesian multilevel models. We quantify midshaft cortical bone rigidity and area (J, CA), midshaft shape index (Imax/Imin), and mean trabecular bone mineral density (BMD) in the distal tibia., Results: All groups show unique combinations of biomechanical properties. Cortical bone rigidity is high in sports that involve impact loading (cricket, running, hockey) and low in nonimpact loaded swimmers and controls. Runners have more anteroposteriorly elliptical midshafts compared to other groups. Interestingly, all athletes have greater trabecular BMD compared to controls, but do not differ credibly among each other., Discussion: Results suggest that cortical midshaft hypertrophy is associated with impact loading while trabecular BMD is positively associated with both impact and nonimpact loading. Midshaft shape is associated with directionality of loading. Individuals from the different categories overlap substantially, but group means differ credibly, suggesting that nuanced group-level inferences of habitual behavior are possible when combinations of trabecular and cortical bone are analyzed., (© 2020 Wiley Periodicals LLC.)

Objective: This project investigates trabecular bone structural variation in the proximal humerus and femur of hunter-gatherer, mixed-strategy agricultural, medieval, and human groups to address three questions: (a) What is the extent of trabecular bone structural variation in the humerus and femur between populations with different inferred activity levels? (b) How does variation in the proximal humerus relate to variation in the proximal femur? (c) Are trabecular bone microstructural variables sexually dimorphic?, Methods: The proximal humerus and femur of 73 adults from five human groups with distinct subsistence strategies were scanned using a micro-computed tomography system. Centralized volumes of interest within the humeral and femoral heads were extracted and analyzed to quantify bone volume fraction, trabecular thickness, trabecular separation, connectivity density, degree of anisotropy, and bone surface density., Results: In the humerus and femur, groups with the highest inferred activity levels have higher bone volume fraction and trabecular thickness, and lower bone surface density than those with lower inferred activity levels. However, the humeral pattern does not exactly mirror that of the femur, which demonstrates a steeper gradient of difference between subsistence groups. No significant differences were identified in trabecular separation. No consistent patterns of sexual dimorphism were present in the humerus or femur., Conclusions: Reduced skeletal robusticity of proximal humeral and femoral trabecular bone corresponds with reduced activity level inferred from subsistence strategy. However, human trabecular bone structural variation is complex and future work should explore how other factors (diet, climate, genetics, disease load, etc.), in addition to activity, influence bone structural variation., (© 2018 Wiley Periodicals, Inc.)

Adaptations indicative of habitual bipedalism are present in the earliest recognized hominins. However, debate persists about various aspects of bipedal locomotor behavior in fossil hominins, including the nature of gait kinematics, locomotor variability across different species, and the degree to which various australopith species engaged in arboreal behaviors. In this study, we analyze variation in trabecular bone structure of the femoral head using a sample of modern humans, extant non-human hominoids, baboons, and fossil hominins attributed to Australopithecus africanus, Paranthropus robustus, and the genus Homo. We use μCT data to characterize the fabric anisotropy, material orientation, and bone volume fraction of trabecular bone to reconstruct hip joint loading conditions in these fossil hominins. Femoral head trabecular bone fabric structure in australopiths is more similar to that of modern humans and Pleistocene Homo than extant apes, indicating that these australopith individuals walked with human-like hip kinematics, including a more limited range of habitual hip joint postures (e.g., a more extended hip) during bipedalism. Our results also indicate that australopiths have robust femoral head trabecular bone, suggesting overall increased loading of the musculoskeletal system comparable to that imposed by extant apes. These results provide new evidence of human-like bipedal locomotion in Pliocene hominins, even while other aspects of their musculoskeletal systems retain ape-like characteristics., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Many studies have noted that the bones of the human upper limb display bilateral asymmetry, commonly linking this asymmetry in external and internal morphology to handedness and lateralization. Few studies, however, have attempted to track asymmetry throughout ontogeny. This study assesses the ontogenetic development of cortical and trabecular bone asymmetry in the humerus. We predict that directional asymmetry in structural properties will emerge in concert with hand preference and increased activity levels during the juvenile period. Paired humeri from 57 individuals from the Norris Farms #36 archaeological skeletal collection ranging in age from neonate to adult were used in the current study. Cortical bone cross-sectional properties and three-dimensional trabecular bone structure were quantified from microcomputed tomography data. The results indicate significant absolute asymmetry in all measured cortical and trabecular bone variables across all ages. Trabecular bone displays significantly higher absolute asymmetry than cortical bone. Contrary to expectations, however, this study found very little evidence for significant directional asymmetry in humeral length and cortical or trabecular bone variables, except in adults. The presence of significant absolute asymmetry in all age groups, and the lack of significant directional asymmetry in almost all variables at all ages, suggests that structural differences due to higher levels of habitual loading in the dominant arm are overlain on a template of potentially significant existing asymmetry. Anat Rec, 301:1012-1025, 2018. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

The dispersal of the genus Homo out of Africa approximately 1.8 million years ago (Ma) has been understood within the context of changes in diet, behavior, and bipedal locomotor efficiency. While various morphological characteristics of the knee and ankle joints are considered part of a suite of traits indicative of, and functionally related to, habitual bipedal walking, the timing and phylogenetic details of these morphological changes remain unclear. To evaluate the timing of knee and ankle joint evolution, we apply geometric morphometric methods to three-dimensional digital models of the proximal and distal tibiae of fossil hominins, Holocene Homo sapiens, and extant great apes. Two sets of landmarks and curve semilandmarks were defined on each specimen. Because some fossils were incomplete, digital reconstructions were carried out independently to estimate missing landmarks and semilandmarks. Group shape variation was evaluated through shape-and form-space principal component analysis and fossil specimens were projected to assess variation in the morphological space computed from the extant comparative sample. We show that a derived proximal tibia (knee) similar to that seen in living H. sapiens evolved with early Homo at ∼2 Ma. In contrast, derived characteristics in the distal tibia appear later, probably with the arrival of Homo erectus. These results suggest a dissociation of the morphologies of the proximal and distal tibia, perhaps indicative of divergent functional demands and, consequently, selective pressures at these joints. It appears that longer distance dispersals that delivered the Dmanisi hominins to Georgia by 1.8 Ma and H. erectus to east-southeast Asia by 1.6 Ma were facilitated by the evolution of a morphologically derived knee complex comparable to that of recent humans and an ankle that was morphologically primitive. This research sets the foundation for additional paleontological, developmental, and functional research to better understand the mechanisms underlying the evolution of bipedalism., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Objectives: The fibula transmits loads within the lower limb of hominids. The few studies of variation in the cross-sectional geometric (CSG) properties of the fibula have established differences in its rigidity among groups engaged in distinct habitual loading activities. This study adds to this research by considering the relationship between CSG properties and the anatomical position of the fibula relative to the tibia among groups with differences in documented activity patterns., Material and Methods: We used pQCT scans taken at 50% of the length of the lower leg in 83 healthy young adult collegiate-aged individuals divided into five activity groups: runners, swimmers, cricketers, field hockey players, and non-athletes. We compared variation in calculated CSG properties against the distance between fibular and tibial centroids, as well as the angle of that plane relative to the plane of tibial I max ., Results: Tibial and fibular CSG properties vary with respect to the relative position of the two bones. Tibial CSG properties differ in concert with the relative angle of the fibula to tibial I max , while fibular CSG properties differ with the distance between the elements. Fibulae are more posterior-medially positioned in groups engaged in terrestrial athletics than among swimmers., Discussion: The tibia and fibula experience different loads. The relative position of the two bones leads to compensatory differences in their CSG properties, perhaps due to increased resistance to bending in fibulae with greater distances from the tibia. Examinations of tibial CSG properties without considering the fibula limits interpretations about activity., (© 2017 Wiley Periodicals, Inc.)

Trabecular bone is responsive to mechanical loading, and thus may be a useful tool for interpreting past behaviour from fossil morphology. However, the ability to meaningfully interpret variation in archaeological and hominin trabecular morphology depends on the extent to which trabecular bone properties are integrated throughout the postcranium or are locally variable in response to joint specific loading. We investigate both of these factors by comparing trabecular bone throughout the lower limb between a group of highly mobile foragers and two groups of sedentary agriculturalists. Trabecular bone structure is quantified in four volumes of interest placed within the proximal and distal joints of the femur and tibia. We determine how trabecular structures correspond to inferred behavioural differences between populations and whether the patterns are consistent throughout the limb. A significant correlation was found between inferred mobility level and trabecular bone structure in all volumes of interest along the lower limb. The greater terrestrial mobility of foragers is associated with higher bone volume fraction, and thicker and fewer trabeculae (lower connectivity density). In all populations, bone volume fraction decreases while anisotropy increases proximodistally throughout the lower limb. This observation mirrors reductions in cortical bone mass resulting from proximodistal limb tapering. The reduction in strength associated with reduced bone volume fraction may be compensated for by the increased anisotropy in the distal tibia. A similar pattern of trabecular structure is found throughout the lower limb in all populations, upon which a signal of terrestrial mobility appears to be superimposed. These results support the validity of using lower limb trabecular bone microstructure to reconstruct terrestrial mobility levels from the archaeological and fossil records. The results further indicate that care should be taken to appreciate variation resulting from differences in habitual activity when inferring behaviour from the trabecular structure of hominin fossils through comparisons with modern humans., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objectives: This study aims to evaluate the use of quantitative methods of measuring variation in scalp hair fiber shape and pigmentation and carry out exploratory data analysis on a limited sample of individuals from diverse populations in order to inform future avenues of research for the evolution of modern human hair variation., Methods: Cross-sectional area and shape and average curvature of scalp hair fibers were quantified using ImageJ. Pigmentation was analyzed using chemical methods estimating total melanin content through spectrophotometric methods, and eumelanin and pheomelanin content through HLPC analysis of melanin-specific degradation products., Results: The initial results reinforced findings from earlier, traditional studies. African and African Diaspora scalp hair was significantly curled, (East) Asian hair was significantly thick, and European hair was significantly lighter in color. However, pigmentation analyses revealed a high level of variability in the melanin content of non-European populations and analysis of curvature found a large range of variation in the average curvature of East African individuals., Conclusions: Overall, these results suggest the usefulness of chemical methods for the elucidation of nonperceptible differences in scalp hair color and highlight the need for improvements in our assessment and understanding of hair fiber curvature. Am J Phys Anthropol 160:341-352, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Physically effective fiber is needed by dairy cattle to prevent ruminal acidosis. This study aimed to examine the effects of different sources of physically effective fiber on the populations of fibrolytic bacteria and methanogens. Five ruminally cannulated Holstein cows were each fed five diets differing in physically effective fiber sources over 15 weeks (21 days/period) in a Latin Square design: (1) 44.1% corn silage, (2) 34.0% corn silage plus 11.5% alfalfa hay, (3) 34.0% corn silage plus 5.1% wheat straw, (4) 36.1% corn silage plus 10.1% wheat straw, and (5) 34.0% corn silage plus 5.5% corn stover. The impact of the physically effective fiber sources on total bacteria and archaea were examined using denaturing gradient gel electrophoresis. Specific real-time PCR assays were used to quantify total bacteria, total archaea, the genus Butyrivibrio, Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens and three uncultured rumen bacteria that were identified from adhering ruminal fractions in a previous study. No significant differences were observed among the different sources of physical effective fiber with respect to the microbial populations quantified. Any of the physically effective fiber sources may be fed to dairy cattle without negative impact on the ruminal microbial community.

Objectives: Morphological variation along the human limb reflects complex structural trade-offs between bone strength and mass. Here we assess how varying levels of plasticity and constraint affect this structure and influence the response to habitual loading along the diaphysis., Materials and Methods: Cross-sectional geometric properties including total area, cortical area, and rigidity were compared from the upper (humerus: 50% of length, radius: 66%, 50%, 4%) and lower (tibia: 50%, 38%, 4%) limbs of male varsity-level athletes and matched controls with distinct habitual loading histories., Results: Geometric properties among cricketers and swimmers were significantly greater at the humeral midshaft, mid-proximal radius, and radial midshaft compared to controls. By contrast, no significant differences were found among athletes or controls at the distal radius. The tibial midshafts of hockey players and runners also displayed greater area and rigidity compared to controls. Differences in geometry among the three groups became less pronounced distally, where structure was comparable among athletes and controls at 4% of tibial length. Additionally, coefficients of variation revealed that variation among athletes of the same sport was highest distally in both the upper and lower limb and lowest at midshaft, where structure most closely reflected the activity pattern of each loading group., Discussion: These results support previous research suggesting that distal limb sections are more tightly constrained by safety factors compared to midshafts and proximal sections. Overall, it appears that plasticity and constraint vary not only between limb segments in correspondence to known activity patterns, but also along specific sections of the diaphysis., (© 2015 Wiley Periodicals, Inc.)

The postcranial skeleton of modern Homo sapiens is relatively gracile compared with other hominoids and earlier hominins. This gracility predisposes contemporary humans to osteoporosis and increased fracture risk. Explanations for this gracility include reduced levels of physical activity, the dissipation of load through enlarged joint surfaces, and selection for systemic physiological characteristics that differentiate modern humans from other primates. This study considered the skeletal remains of four behaviorally diverse recent human populations and a large sample of extant primates to assess variation in trabecular bone structure in the human hip joint. Proximal femur trabecular bone structure was quantified from microCT data for 229 individuals from 31 extant primate taxa and 59 individuals from four distinct archaeological human populations representing sedentary agriculturalists and mobile foragers. Analyses of mass-corrected trabecular bone variables reveal that the forager populations had significantly higher bone volume fraction, thicker trabeculae, and consequently lower relative bone surface area compared with the two agriculturalist groups. There were no significant differences between the agriculturalist and forager populations for trabecular spacing, number, or degree of anisotropy. These results reveal a correspondence between human behavior and bone structure in the proximal femur, indicating that more highly mobile human populations have trabecular bone structure similar to what would be expected for wild nonhuman primates of the same body mass. These results strongly emphasize the importance of physical activity and exercise for bone health and the attenuation of age-related bone loss.

Previous studies have shown a strong correspondence between long bone bilateral asymmetry and reported handedness. Here, we compare the pattern of asymmetry in mechanical properties of the humerus and second metacarpal of Pan troglodytes, recent British industrial and medieval populations, and a broad range of human hunter-gatherers, to test whether technological variation corresponds with lateralization in bone function. The results suggest that P. troglodytes are left-lateralized in the morphology of the humerus and right-lateralized in the second metacarpal, while all human populations are predominantly right-biased in the morphology of these bones. Among human populations, the second metacarpals of 63% of hunter-gatherers show right-hand bias, a frequency similar to that found among chimpanzees. In contrast, the medieval and recent British populations show over 80% right-lateralization in the second metacarpal. The proportion of individuals displaying right-directional asymmetry is less than the expected 90% among all human groups. The variation observed suggests that the human pattern of right-biased asymmetry developed in a mosaic manner throughout human history, perhaps in response to technological development., (© 2013 New York Academy of Sciences.)

Ontogenetic growth processes in human long bones are key elements, determining the variability of adult bone structure. This study seeks to identify and describe the interaction between ontogenetic growth periods and changes in femoral and tibial diaphyseal shape. Femora and tibiae (n = 46) ranging developmentally from neonate to skeletally mature were obtained from the Norris Farms No. 36 archeological skeletal series. High-resolution X-ray computed tomography scans were collected. Whole-diaphysis cortical bone drift patterns and relative bone envelope modeling activity across ages were assessed in five cross-sections per bone (total bone length: 20%, 35%, 50%, 65%, and 80%) by measuring the distance from the section centroid to the endosteal and periosteal margins in eight sectors using ImageJ. Pearson correlations were performed to document and interpret the relationship between the cross-sectional shape (Imax /Imin ), total subperiosteal area, cortical area, and medullary cavity area for each slice location and age for both the femur and the tibia. Differences in cross-sectional shape between age groups at each cross-sectional position were assessed using nonparametric Mann-Whitney U tests. The data reveal that the femoral and tibial midshaft shape are relatively conserved throughout growth; yet, conversely, the proximal and distal femoral diaphysis and proximal tibial diaphysis appear more sensitive to developmentally induced changes in mechanical loading. Two time periods of accelerated change are identified: early childhood and prepuberty/adolescence., (Copyright © 2013 Wiley Periodicals, Inc.)

Descriptions of Pleistocene activity patterns often derive from comparisons of long bone diaphyseal robusticity across contemporaneous fossilized hominins. The purpose of this study is to augment existing understanding of Pleistocene hominin mobility patterns by interpreting fossil variation through comparisons with a) living human athletes with known activity patterns, and b) Holocene foragers where descriptions of group-level activity patterns are available. Relative tibial rigidity (midshaft tibial rigidity (J)/midshaft humeral rigidity (J)) was compared amongst Levantine and European Neandertals, Levantine and Upper Palaeolithic Homo sapiens, Holocene foragers and living human athletes and controls. Cross-country runners exhibit significantly (p<0.05) greater relative tibial rigidity compared with swimmers, and higher values compared with controls. In contrast, swimmers displayed significantly (p<0.05) lower relative tibial rigidity than both runners and controls. While variation exists among all Holocene H. sapiens, highly terrestrially mobile Later Stone Age (LSA) southern Africans and cross-country runners display the highest relative tibial rigidity, while maritime Andaman Islanders and swimmers display the lowest, with controls falling between. All fossil hominins displayed relative tibial rigidity that exceeded, or was similar to, the highly terrestrially mobile Later Stone Age southern Africans and modern human cross-country runners. The more extreme skeletal structure of most Neandertals and Levantine H. sapiens, as well as the odd Upper Palaeolithic individual, appears to reflect adaptation to intense and/or highly repetitive lower limb (relative to upper limb) loading. This loading may have been associated with bipedal travel, and appears to have been more strenuous than that encountered by even university varsity runners, and Holocene foragers with hunting grounds 2000-3000 square miles in size. Skeletal variation among the athletes and foraging groups is consistent with known or inferred activity profiles, which support the position that the Pleistocene remains reflect adaptation to extremely active and mobile lives., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Most analyses of trabecular microarchitecture in mammals have focused on the functional significance of interspecific variation, but they have not effectively considered the influence of body size or phylogeny on bone architecture. The goals of this study were to determine the relationship between trabecular bone and body size in the humeral and femoral heads of extant primates, and to assess the influence of phylogeny on bone microstructure. Using a sample of 235 individuals from 34 primate species, ranging in body size from 0.06 to 130 kg, the relationships between trabecular bone structure and body size were assessed by using conventional and phylogenetic regression analyses. Bone volume fraction, trabecular thickness and trabecular spacing increase with body size, whereas bone surface-area-to-volume ratio decreases. Shape variables such as trabecular number, connectivity density and degree of anisotropy scale inversely with size. Most of these variables scale with significant negative allometry, except bone surface-area-to-volume ratio, which scales with slight positive allometry. Phylogenetic regressions indicate a relatively weak phylogenetic signal in some trabecular bone variables. These data demonstrate that, relative to body size, large primates have thinner and more tightly packed trabeculae than small primates. The relatively thin trabeculae in large primates and other mammals, coupled with constraints on trabecular thickness related to osteocyte function, suggest that increased skeletal loads in the postcranial joints of large mammals are probably mitigated not only through alterations in trabecular microarchitecture, but also through other mechanisms such as changes in cortical bone distribution, limb posture and gait speed.

Cross-sectional geometric (CSG) properties of human long bone diaphyses are typically calculated from both periosteal and endosteal contours. Though quantification of both is desirable, periosteal contours alone have provided accurate predictions of CSG properties at the midshaft in previous studies. The relationship between CSG properties calculated from external contours and "true" (endosteal and periosteal) CSG properties, however, has yet to be examined along the whole diaphysis. Cross-sectional computed tomography scans were taken from 21 locations along humeral, femoral, and tibial diaphyses in 20 adults from a late prehistoric central Illinois Valley cemetery. Mechanical properties calculated from images with (a) artificially filled medullary cavities ("solid") and (b) true unaltered cross-sections were compared at each section location using least squares regression. Results indicate that, in this sample, polar second moments of area (J), polar section moduli (Z(p) ), and cross-sectional shape (I(max) /I(min) ) calculated from periosteal contours correspond strongly with those calculated from cross-sections that include the medullary cavity. Correlations are high throughout most of the humeral diaphysis and throughout large portions of femoral and tibial diaphyses (R(2) = 0.855-0.998, all P < 0.001, %SEE ≤ 8.0, %PE ≤ 5.0), the major exception being the proximal quarter of the tibial diaphysis for J and Z(p). The main source of error was identified as variation in %CA. Results reveal that CSG properties quantified from periosteal contours provide comparable results to (and are likely to detect the same differences among individuals as) true CSG properties along large portions of long bone diaphyses., (Copyright © 2013 Wiley Periodicals, Inc.)

Although the correspondence between habitual activity and diaphyseal cortical bone morphology has been demonstrated for the fore- and hind-limb long bones of primates, the relationship between trabecular bone architecture and locomotor behavior is less certain. If sub-articular trabecular and diaphyseal cortical bone morphology reflects locomotor patterns, this correspondence would be a valuable tool with which to interpret morphological variation in the skeletal and fossil record. To assess this relationship, high-resolution computed tomography images from both the humeral and femoral head and midshaft of 112 individuals from eight anthropoid genera (Alouatta, Homo, Macaca, Pan, Papio, Pongo, Trachypithecus, and Symphalangus) were analyzed. Within-bone (sub-articular trabeculae vs. mid-diaphysis), between-bone (forelimb vs. hind limb), and among-taxa relative distributions (femoral:humeral) were compared. Three conclusions are evident: (1) Correlations exists between humeral head sub-articular trabecular bone architecture and mid-humerus diaphyseal bone properties; this was not the case in the femur. (2) In contrast to comparisons of inter-limb diaphyseal bone robusticity, among all species femoral head trabecular bone architecture is significantly more substantial (i.e., higher values for mechanically relevant trabecular bone architectural features) than humeral head trabecular bone architecture. (3) Interspecific comparisons of femoral morphology relative to humeral morphology reveal an osteological "locomotor signal" indicative of differential use of the forelimb and hind limb within mid-diaphysis cortical bone geometry, but not within sub-articular trabecular bone architecture., (Copyright © 2011 Wiley Periodicals, Inc.)

Understanding the mechanically-mediated response of trabecular bone to locomotion-specific loading patterns would be of great benefit to comparative mammalian evolutionary morphology. Unfortunately, assessments of the correspondence between individual trabecular bone features and inferred behavior patterns have failed to reveal a strong locomotion-specific signal. This study assesses the relationship between inferred locomotor activity and a suite of trabecular bone structural features that characterize bone architecture. High-resolution computed tomography images were collected from the humeral and femoral heads of 115 individuals from eight anthropoid primate genera (Alouatta, Homo, Macaca, Pan, Papio, Pongo, Trachypithecus, Symphalangus). Discriminant function analyses reveal that subarticular trabecular bone in the femoral and humeral heads is significantly different among most locomotor groups. The results indicate that when a suite of femoral head trabecular features is considered, trabecular number and connectivity density, together with fabric anisotropy and the relative proportion of rods and plates, differentiate locomotor groups reasonably well. A similar, yet weaker, relationship is also evident in the trabecular architecture of the humeral head. The application of this multivariate approach to analyses of trabecular bone morphology in recent and fossil primates may enhance our ability to reconstruct locomotor behavior in the fossil record.

Unique compared with recent and prehistoric Homo sapiens, Neandertal humeri are characterised by a pronounced right-dominant bilateral strength asymmetry and an anteroposteriorly strengthened diaphyseal shape. Remodeling in response to asymmetric forces imposed during regular underhanded spear thrusting is the most influential explanatory hypothesis. The core tenet of the "Spear Thrusting Hypothesis", that underhand thrusting requires greater muscle activity on the right side of the body compared to the left, remains untested. It is unclear whether alternative subsistence behaviours, such as hide processing, might better explain this morphology. To test this, electromyography was used to measure muscle activity at the primary movers of the humerus (pectoralis major (PM), anterior (AD) and posterior deltoid (PD)) during three distinct spear-thrusting tasks and four separate scraping tasks. Contrary to predictions, maximum muscle activity (MAX) and total muscle activity (TOT) were significantly higher (all values, p<.05) at the left (non-dominant) AD, PD and PM compared to the right side of the body during spear thrusting tasks. Thus, the muscle activity required during underhanded spearing tasks does not lend itself to explaining the pronounced right dominant strength asymmetry found in Neandertal humeri. In contrast, during the performance of all three unimanual scraping tasks, right side MAX and TOT were significantly greater at the AD (all values, p<.01) and PM (all values, p<.02) compared to the left. The consistency of the results provides evidence that scraping activities, such as hide preparation, may be a key behaviour in determining the unusual pattern of Neandertal arm morphology. Overall, these results yield important insight into the Neandertal behavioural repertoire that aided survival throughout Pleistocene Eurasia.

During hominin plantigrade locomotion, the weight-bearing function of the fibula has been considered negligible. Nevertheless, studies conducted on human samples have demonstrated that, even if less than that of the tibia, the load-bearing function of the fibula still represents a considerable portion of the entire load borne by the leg. The present study assesses whether variation in habitual lower limb loading influences fibular morphology in a predictable manner. To achieve this, both fibular and tibial morphology were compared amongst modern human athletes (field hockey players and cross-country runners) and matched sedentary controls. Peripheral quantitative computed tomography was used to capture two-dimensional, cross-sectional bone images. Geometric properties were measured at the midshaft for each bone. Results show a trend of increased fibular rigidity from control to runners through to field hockey players. Moreover, relative fibular robusticity (fibula/tibia) is significantly greater in hockey players compared with runners. These results are likely the consequence of habitual loading patterns performed by these athletes. Specifically, the repeated directional changes associated with field hockey increase the mediolateral loading on the lower leg in a manner that would not necessarily be expected during cross-country running. The present study validates the use of the fibula in association with the tibia as a mean to provide a more complete picture of leg bone functional adaptations. Therefore, the fibula can be added to the list of bones generally used (tibia and femur) to assess the correspondence between mobility patterns and skeletal morphology for past human populations., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The presumed link between bilateral asymmetry and lateralized habitual activity in extinct hominins is the basis upon which inferences of 'hand preference' often derive. While this presumption is reasonable, in-vivo comparisons of skeletal asymmetries and self-reported handedness are rare, and as a result the accuracy of these inferences is questionable. To assess this relationship in living humans, reported 'handedness' was compared against peripheral quantitative computed tomography (pQCT) derived bilateral measurements of humeral, ulnar, and tibial midshaft cortical area (CA) and torsional rigidity (J). Significant bilateral differences were found in the humerus for all groups, and in the ulna for the cricketer and field hockey sub-samples. Additionally, cricketers' non-dominant tibiae were more robust than their dominant tibiae. An assessment of 'Dominance Asymmetry' revealed that measures of CA and J were higher in the dominant humeri in ∼90% of participants; in the ulna this was true in ∼75% of cases, and in the tibia CA and J were higher in the dominant limb less than 50% of the time. Comparisons of (self)'Reported' hand preference against 'Predicted' hand preference (based on the calculation of % Directional Asymmetry) revealed a low level of error for predictions based on both humeral (∼4-5% error) and ulnar (6-11% error) asymmetry. Error was decreased with the exclusion of individuals displaying less than 2.5-5% asymmetry. Contrarily, predictions based on tibial analyses had a much higher level of 'error' (∼45%). Overall, the results support currently accepted approaches for inferring 'hand preference' from measures of upper limb geometric asymmetry in the hominin skeleton., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Variation in femoral and tibial diaphyseal shape is used as an indicator of adaptation to patterns of terrestrial mobility. Recent experimentation has implied that lower limb diaphyseal shape may be primarily influenced by lower limb length, and less so by mobility patterns. If valid, this would, at most, render previous interpretations of mobility patterns based on analyses of diaphyseal shape questionable, and, at least, require additional standardization that considers the influence of limb length. Although the consequences could be profound, this implication has yet to be directly tested. Additionally, the influence of body breadth on tibial shape (and to a lesser extent femoral shape) remains uncertain. Tibial and femoral cross-sectional midshaft shape measurements, taken from nine Pleistocene and Holocene skeletal populations, were compared against lower limb length, limb segment length, and bi-iliac breadth. Generally, limb length and limb segment length do not significantly influence femoral or tibial midshaft shape. After controlling for body mass greater bi-iliac breadth is associated with a relative mediolateral strengthening of the femoral midshaft, while the influence of a wider body shape (BIB/length) is associated with a relative M-L strengthening of the tibia and femur of males, and the tibia of females. We conclude that; (1) mechanical interpretations of lower limb diaphyseal shape are most parsimonious due to the lack of evidence for a consistent relationship between segment length and shape; however, (2) further work is required to investigate the influence of bi-iliac breadth on both femoral and tibial midshaft shape., (Copyright © 2010 Wiley-Liss, Inc.)

Bone shape, mass, structural geometry, and material properties determine bone strength. This study describes novel software that uses peripheral quantitative computed tomography (pQCT) images to quantify cortical bone shape and investigates whether the combination of shape-sensitive and manufacturer's software enhances the characterization of tibiae from contrasting populations. Existing tibial pQCT scans (4% and 50% sites) from Gambian (n=38) and British (n=38) women were used. Bone mass, cross-sectional area (CSA), and geometry were determined using manufacturer's software; cross-sectional shape was quantified using shape-sensitive software. At 4% site, Gambian women had lower total bone mineral content (BMC: -15.4%), CSA (-13.4%), and trabecular bone mineral density (BMD: -19%), but higher cortical subcortical BMD (6.1%). At 50% site, Gambian women had lower cortical BMC (-7.6%), cortical CSA (-12.6%), and mean cortical thickness (-15.0%), but higher cortical BMD (4.9%) and endosteal circumference (8.0%). Shape-sensitive software supported the finding that Gambian women had larger tibial endosteal circumference (9.8%), thinner mean cortical thickness (-26.5%) but smaller periosteal circumference (-5.6%). Shape-sensitive software revealed that Gambian women had tibiae with shorter maximum width (-7.6%) and thinner cortices (-22% to -41.2%) and more closely resembled a circle or ellipse. Significant differences remained after adjusting for age, height, and weight. In conclusion, shape-sensitive software enhanced the characterization of tibiae in 2 contrasting groups of women.

Mobility patterns affect the loads placed on the lower limbs during locomotion and may influence variation in lower limb diaphyseal robusticity and shape. This relationship commonly forms the basis for inferring mobility patterns from hominin fossil and skeletal remains. This study assesses the correspondence between athletic histories, varying by loading intensity, repetition and directionality, measured using a recall questionnaire, and peripheral quantitative computed tomography-derived measurements of tibial diaphysis rigidity and shape. Participants included male university varsity cross-country runners (n = 15), field hockey players (n = 15), and controls (n = 20) [mean age: 22.1 (SD +/- 2.6) years]. Measurements of tibial rigidity (including J, %CA, Imax, Imin, and average cortical thickness) of both runners and field hockey players were greater than controls (P < or = 0.05). Differences in tibial shape (Imax/Imin, P < or = 0.05) between runners and hockey players reflect pronounced maximum plane (Imax) rigidity in runners, and more symmetrical hypertrophy (Imax, Imin) among hockey players. This corresponds with the generally unidirectional locomotor patterns of runners, and the multidirectional patterns of hockey players. These results support the relationship between mobility and tibial diaphysis morphology as it is generally interpreted in the anthropological literature, with greater levels of mobility associated with increased diaphyseal robusticity and shape variation. Although exercise intensity may be the primary influence on these properties, the repetitiveness of the activity also deserves consideration. In conclusion, bone morphological patterns can reflect habitual behaviors, with adaptation to locomotor activities likely contributing to variation in tibial rigidity and shape properties in archaeological and fossil samples., (Copyright 2009 Wiley-Liss, Inc.)

Variation in upper limb long bone cross-sectional properties may reflect a phenotypically plastic response to habitual loading patterns. Structural differences between limb bones have often been used to infer past behavior from hominin remains; however, few studies have examined direct relationships between behavioral differences and bone structure in humans. To help address this, cross-sectional images (50% length) of the humeri and ulnae of university varsity-level swimmers, cricketers, and controls were captured using peripheral quantitative computed tomography. High levels of humeral robusticity were found in the dominant arms of cricketers, and bilaterally among swimmers, whereas the most gracile humeri were found in both arms of controls, and the nondominant arms of cricketers. In addition, the dominant humeri of cricketers were more circular than controls. The highest levels of ulnar robusticity were also found in the dominant arm of cricketers, and bilaterally amongst swimmers. Bilateral asymmetry in humeral rigidity among cricketers was greater than swimmers and controls, while asymmetry for ulnar rigidity was greater in cricketers than controls. The results suggest that more mechanically loaded upper limb elements--unilaterally or bilaterally--are strengthened relative to less mechanically loaded elements, and that differences in mechanical loading may have a more significant effect on proximal compared to distal limb segments. The more circular humerus in the dominant arm in cricketers may be an adaptation to torsional strain associated with throwing activities. The reported correspondence between habitual activity patterns and upper limb diaphyseal properties may inform future behavioral interpretations involving hominin skeletal remains., (Copyright 2009 Wiley-Liss, Inc.)

Measures of diaphyseal robusticity have commonly been used to investigate differences in bone strength related to body size, behavior, climate, and other factors. The most common methods of quantifying robusticity involve external diameters, or cross-sectional geometry. The data derived from these different methods are often used to address similar research questions, yet the compatibility of the resulting data has not been thoroughly tested. This study provides the first systematic comparison of externally derived measures of postcranial robusticity, with those based upon cross-sectional geometry. It includes sections taken throughout the skeleton, comparisons of prediction errors associated with different measurements, and analysis of the implications of different methods of body size standardization on the prediction of relative bone strength. While the results show reasonable correlations between diaphyseal diameters and strengths derived from cross-sectional geometry, considerable prediction errors are found in many cases. A new approach to externally based quantification of diaphyseal robusticity based upon moulding of sub-periosteal contours is proposed. This method maximizes correlation with cross-sectional geometry (r(2) = .998) and minimizes prediction errors in all cases. The results underscore the importance of accurate periosteal measurement in the quantification of bone strength, and suggest that, regardless of theoretical scaling predictions, external area based robusticity estimates involving the product of diaphyseal diameters are most directly comparable to cross-sectional geometric properties when they are standardized using the product of body mass and bone length., ((c) 2007 Wiley-Liss, Inc.)

The effect of hypoxic breathing on pulmonary O(2) uptake (VO(2p)), leg blood flow (LBF) and O(2) delivery and deoxygenation of the vastus lateralis muscle was examined during constant-load single-leg knee-extension exercise. Seven subjects (24 +/- 4 years; mean +/-s.d.) performed two transitions from unloaded to moderate-intensity exercise (21 W) under normoxic and hypoxic (P(ET)O(2)= 60 mmHg) conditions. Breath-by-breath VO(2p) and beat-by-beat femoral artery mean blood velocity (MBV) were measured by mass spectrometer and volume turbine and Doppler ultrasound (VingMed, CFM 750), respectively. Deoxy-(HHb), oxy-, and total haemoglobin/myoglobin were measured continuously by near-infrared spectroscopy (NIRS; Hamamatsu NIRO-300). VO(2p) data were filtered and averaged to 5 s bins at 20, 40, 60, 120, 180 and 300 s. MBV data were filtered and averaged to 2 s bins (1 contraction cycle). LBF was calculated for each contraction cycle and averaged to 5 s bins at 20, 40, 60, 120, 180 and 300 s. VO(2p) was significantly lower in hypoxia throughout the period of 20, 40, 60 and 120 s of the exercise on-transient. LBF (l min(-1)) was approximately 35% higher (P > 0.05) in hypoxia during the on-transient and steady-state of KE exercise, resulting in a similar leg O(2) delivery in hypoxia and normoxia. Local muscle deoxygenation (HHb) was similar in hypoxia and normoxia. These results suggest that factors other than O(2) delivery, possibly the diffusion of O(2,) were responsible for the lower O(2) uptake during the exercise on-transient in hypoxia.