Biomechanics in anthropology

Biomechanics is the set of tools that explain organismal movement and mechanical behavior and links the organism to the physicality of the world. As such, biomechanics can relate behaviors and culture to the physicality of the organism. Scale is critical to biomechanical analyses, as the constitutive equations that matter differ depending on the scale of the question. Within anthropology, biomechanics has had a wide range of applications, from understanding how we and other primates evolved to understanding the effects of technologies, such as the atlatl, and the relationship between identity, society, culture, and medical interventions, such as prosthetics. Like any other model, there is great utility in biomechanical models, but models should be used primarily for hypothesis testing and not data generation except in the rare case where models can be robustly validated. The application of biomechanics within anthropology has been extensive, and holds great potential for the future.

The relational agency of plants in produce supply chains during COVID-19: "Mother nature takes her course"

The Ontario Food Terminal is a central node in the North American food system, the third largest wholesale produce market on the continent. During the first 20 months of the COVID-19 pandemic, qualitative research was conducted with food system actors to understand the impact of the public health crisis on produce supply chains. This paper contributes to the study of nonhumans in agri-food networks and rural spaces, specifically human-plant relations. Employing a posthumanist lens to investigate why produce supply chains continued to flow during the pandemic, it is argued that plants helped to keep supply chains moving at the Terminal in the face of crisis. Plant agency in this case is found to be the product of relationships with humans as well as nonhuman systems. This agency is collective in nature and is rooted in the plants' relationships with humans as perishable foods and commodities as well as ecosystem relationships. Further, the paper demonstrates how plant agency, that had political effects during the pandemic, is normalizing. This underlines the importance of considering the nature of the relationship in the context of relational agency, and highlights that it cannot be assumed that plants are allies in food system change.

Transformative learning for a sustainable and healthy future through ecosystem approaches to health: insights from 15 years of co-designed ecohealth teaching and learning experiences

This paper presents insights from the work of the Canadian Community of Practice in Ecosystem Approaches to Health (CoPEH-Canada) and 15 years (2008-2022) of land-based, transdisciplinary, learner-centred, transformative learning and training. We have oriented our learning approaches to Head, Hands, and Heart, which symbolise cognitive, psychomotor, and affective learning, respectively. Psychomotor and affective learning are necessary to grapple with and enact far-reaching structural changes (eg, decolonisation) needed to rekindle healthier, reciprocal relationships with nature and each other. We acknowledge that these approaches have been long understood by Indigenous colleagues and communities. We have developed a suite of teaching techniques and resources through an iterative and evolving pedagogy based on participatory approaches and operating reciprocal, research-pedagogical cycles; integrated different approaches and ways of knowing into our pedagogy; and built a networked Community of Practice for continued learning. Planetary health has become a dominant framing for health-ecosystem interactions. This Viewpoint underscores the depth of existing scholarship, collaboration, and pedagogical expertise in ecohealth teaching and learning that can inform planetary health education approaches.

Skull variation in Afro-Eurasian monkeys results from both adaptive and non-adaptive evolutionary processes

Afro-Eurasian monkeys originated in the Miocene and are the most species-rich modern primate family. Molecular and fossil data have provided considerable insight into their evolutionary divergence, but we know considerably less about the evolutionary processes that underlie these differences. Here, we apply tests developed from quantitative genetics theory to a large (n > 3000) cranio-mandibular morphometric dataset, investigating the relative importance of adaptation (natural selection) and neutral processes (genetic drift) in shaping diversity at different taxonomic levels, an approach applied previously to monkeys of the Americas, apes, hominins, and other vertebrate taxa. Results indicate that natural selection, particularly for differences in size, plays a significant role in diversifying Afro-Eurasian monkeys as a whole. However, drift appears to better explain skull divergence within the subfamily Colobinae, and in particular the African colobine clade, likely due to habitat fragmentation. Small and declining population sizes make it likely that drift will continue in this taxon, with potentially dire implications for genetic diversity and future resilience in the face of environmental change. For the other taxa, many of whom also have decreasing populations and are threatened, understanding adaptive pressures similarly helps identify relative vulnerability and may assist with prioritising scarce conservation resources.

Intimate ecosystems: the microbiome and the ecological determinants of health

The ecological determinants of health make explicit the ways in which human health and well-being depend on the biosphere and its systems. Water, oxygen, and food are listed along with soil systems, water systems, material for shelter, energy, the ozone layer and a stable climate. Research in the sciences is uncovering the critical role that the earth microbiome, including the human microbiome, plays in human health. The relationship between commensal microbiota and the systems of the human body, as well as the ways in which these systems are interdependent with other ecosystems such as food systems, invites revisiting the ecological determinants of health. In this commentary, I argue that microbiota, including the human microbiome, should be considered ecological determinants of health. Such a characterization would recognize the importance of the microbiome to human health. It would also frame this as a public health issue and raise questions about health equity, including who benefits from the knowledge produced through biomedical research.

StW 573 Australopithecus prometheus: Its Significance for an Australopith Bauplan

The StW 573 skeleton of Australopithecus prometheus from Sterkfontein Member 2 is some 93% complete and thus by far the most complete member of that genus yet found. Firmly dated at 3.67 Ma, it is one of the earliest specimens of its genus. A crucial aspect of interpretation of locomotor behaviour from fossil remains is an understanding of the palaeoenvironment in which the individual lived and the manner in which it would have used it. While the value of this ecomorphological approach is largely accepted, it has not been widely used as a stable framework on which to build evolutionary biomechanical interpretations. Here, we collate the available evidence on StW 573's anatomy in order, as far as currently possible, to reconstruct what might have been this individual's realized and potential niche. We explore the concept of a common Australopithecus "bauplan" by comparing the morphology and ecological context of StW 573 to that of paenocontemporaneous australopiths including Australopithecus anamensis and KSD-VP-1/1 Australopithecus afarensis. Each was probably substantially arboreal and woodland-dwelling, relying substantially on arboreal resources. We use a hypothesis-driven approach, tested by: virtual experiments, in the case of extinct species; biomechanical analyses of the locomotor behaviour of living great ape species; and analogical experiments with human subjects. From these, we conclude that the habitual locomotor mode of all australopiths was upright bipedalism, whether on the ground or on branches. Some later australopiths such as Australopithecus sediba undoubtedly became more terrestrial, allowing sacrifice of arboreal stability in favour of manual dexterity. Indeed, modern humans retain arboreal climbing skills but have further sacrificed arboreal effectiveness for enhanced ability to sustain striding terrestrial bipedalism over much greater distances. We compare StW 573's locomotor adaptations to those of living great apes and protohominins, and agree with those earlier observers who suggest that the common panin-hominin last common ancestor was postcranially more like Gorilla than Pan.

Ontogenetic and morphological variation in primate long bones reflects signals of size and behavior

OBJECTIVES

Many primates change their locomotor behavior as they mature from infancy to adulthood. Here we investigate how long bone cross-sectional geometry in Pan, Gorilla, Pongo, Hylobatidae, and Macaca varies in shape and form over ontogeny, including whether specific diaphyseal cross sections exhibit signals of periosteal adaptation or canalization.

MATERIALS AND METHODS

Diaphyseal cross sections were analyzed in an ontogenetic series across infant, juvenile, and adult subgroups. Three-dimensional laser-scanned long bone models were sectioned at midshaft (50% of biomechanical length) and distally (20%) along the humerus and femur. Traditional axis ratios acted as indices of cross-sectional circularity, while geometric morphometric techniques were used to study cross-sectional allometry and ontogenetic trajectory.

RESULTS

The humeral midshaft is a strong indicator of posture and locomotor profile in the sample across development, while the mid-femur appears more reflective of shifts in size. By comparison, the distal diaphyses of both limb elements are more ontogenetically constrained, where periosteal shape is largely static across development relative to size, irrespective of a given taxon's behavior or ecology.

DISCUSSION

Primate limb shape is not only highly variable between taxa over development, but at discrete humeral and femoral diaphyseal locations. Overall, periosteal shape of the humeral and femoral midshaft cross sections closely reflects ontogenetic transitions in behavior and size, respectively, while distal shape in both bones appears more genetically constrained across intraspecific development, regardless of posture or size. These findings support prior research on tradeoffs between function and safety along the limbs.

Evaluation of VIDAS® Listeria species Xpress (LSX) Immunoassay Method for the Detection of Listeria species in Foods: Collaborative Study

In a multilaboratory study, the effectiveness of an alternative method for rapid screening of Listeria species compared to traditional reference methods was demonstrated in a variety of food products. A collaborative study was conducted to compare the VIDAS® Listeria species Xpress (LSX) method and the standard cultural methods for the detection of Listeria species in foods. Six food types were tested: vanilla ice cream, cheddar cheese, raw ground beef, frozen green beans, deli turkey, and cooked shrimp. Each food, inoculated with a different Listeria strain at two levels and uninoculated test portions, was analyzed by each method. A total of 15 laboratories representing government and industry participated. In this study 1134 tests were analyzed in the statistical analysis. There were 490 positives by the VIDAS LSX method using the sample boiling step, 483 positives by the VIDAS LSX method using the Heat and Go system, and 439 positives by the standard culture methods. Overall, the Chi-square result for the VIDAS LSX method with boiling for all foods was 7.25, indicating a significant statistical difference between the VIDAS method and the standard methods at the 5% confidence. For the VIDAS LSX method with the Heat and Go system, the Chi-square result for all foods was 5.37, indicating a significant statistical difference between the VIDAS LSX assay with the Heat and Go system and the standard methods at the 5% level of significance. In both cases, the VIDAS method was more sensitive than the standard methods. The LSX method detects Listeria species in foods with negative or presumptive positive results in a minimum of 30 h compared to at least 5 days for the cultural methods. Based on the results of this collaborative study, it is recommended that the VIDAS LSX method be adopted as an AOAC Official MethodSM for the detection of Listeria species in dairy products, vegetables, seafood, raw meats and poultry, and processed meats and poultry.

Insights into the evolution of social systems and species from baboon studies

Baboons, members of the genus Papio, comprise six closely related species distributed throughout sub-Saharan Africa and southwest Arabia. The species exhibit more ecological flexibility and a wider range of social systems than many other primates. This article summarizes our current knowledge of the natural history of baboons and highlights directions for future research. We suggest that baboons can serve as a valuable model for complex evolutionary processes, such as speciation and hybridization. The evolution of baboons has been heavily shaped by climatic changes and population expansion and fragmentation in the African savanna environment, similar to the processes that acted during human evolution. With accumulating long-term data, and new data from previously understudied species, baboons are ideally suited for investigating the links between sociality, health, longevity and reproductive success. To achieve these aims, we propose a closer integration of studies at the proximate level, including functional genomics, with behavioral and ecological studies.

Disrupted seasonal biology impacts health, food security and ecosystems

The rhythm of life on earth is shaped by seasonal changes in the environment. Plants and animals show profound annual cycles in physiology, health, morphology, behaviour and demography in response to environmental cues. Seasonal biology impacts ecosystems and agriculture, with consequences for humans and biodiversity. Human populations show robust annual rhythms in health and well-being, and the birth month can have lasting effects that persist throughout life. This review emphasizes the need for a better understanding of seasonal biology against the backdrop of its rapidly progressing disruption through climate change, human lifestyles and other anthropogenic impact. Climate change is modifying annual rhythms to which numerous organisms have adapted, with potential consequences for industries relating to health, ecosystems and food security. Disconcertingly, human lifestyles under artificial conditions of eternal summer provide the most extreme example for disconnect from natural seasons, making humans vulnerable to increased morbidity and mortality. In this review, we introduce scenarios of seasonal disruption, highlight key aspects of seasonal biology and summarize from biomedical, anthropological, veterinary, agricultural and environmental perspectives the recent evidence for seasonal desynchronization between environmental factors and internal rhythms. Because annual rhythms are pervasive across biological systems, they provide a common framework for trans-disciplinary research.

Exploring morphological generality in the Old World monkey postcranium using an ecomorphological framework

Nearly all primates are ecologically dependent on trees, but they are nonetheless found in an enormous range of habitats, from highly xeric environments to dense rainforest. Most primates have a relatively 'generalised' skeleton, enabling locomotor flexibility and facilitating other crucial functions, such as manual foraging and grooming. This paper explores the associations between habitat, locomotion and morphology in the forelimbs of cercopithecids (Old World monkeys), contextualising their skeletal ecomorphological patterns with those of other mammals, and complementing functional morphological analyses with phylogenetic comparative techniques. The ecomorphological signals present in the generalised primate postcranium, and how an ancestral arboreal 'bauplan' might be modified to incorporate terrestriality or exploit distinct arboreal substrates, are investigated. Analysis of ecomorphological variation in guenons indicates that terrestrial Chlorocebus species retain core elements of a general guenon form, with modifications for terrestriality that vary by species. Adaptation to different modes of arboreality has also occurred in Cercopithecus. The considerable morphological similarity in the guenons sampled emphasises the importance of generality in the primate postcranium - much forelimb variation appears to have emerged stochastically, with a smaller number of traits having a strong functional signal. Analysis of a broader sample of cercopithecids and comparison with felids, suids and bovids indicates that although the cercopithecid humerus has functional morphological signals that enable specimens to be assigned with a reasonable degree of certainty to habitat groups, there is considerable overlap in the specimens assigned to each habitat group. This probably reflects ecological dependence on trees, even in predominantly terrestrial species, as well as the multiple functions of the forelimb and, in some cases, wide geographic distributions that promote intraspecific variation. The use of phylogenetic correction reduced the discriminatory power of the models, indicating that, like allometry, phylogeny contains important ecomorphological information, and should not necessarily be factored out of analyses.

Biogeographic variation in the baboon: dissecting the cline

All species demonstrate intraspecific anatomical variation. While generalisations such as Bergman's and Allen's rules have attempted to explain the geographic structuring of variation with some success, recent work has demonstrated limited support for these in certain Old World monkeys. This study extends this research to the baboon: a species that is widely distributed across sub-Saharan Africa and exhibits clinal variation across an environmentally disparate range. This study uses trend surface analysis to map the pattern of skull variation in size and shape in order to visualise the main axes of morphological variation. Patterns of shape and size-controlled shape are compared to highlight morphological variation that is underpinned by allometry alone. Partial regression is used to dissociate the effects of environmental terms, such as rainfall, temperature and spatial position. The diminutive Kinda baboon is outlying in size, so analyses were carried out with and without this taxon. Skull size variation demonstrates an east-west pattern, with small animals at the two extremes and large animals in Central and Southern Africa. Shape variation demonstrates the same geographical pattern as skull size, with small-sized animals exhibiting classic paedomorphic morphology. However, an additional north-south axis of variation emerges. After controlling for skull size, the diminutive Kinda baboon is no longer an outlier for size and shape. Also, the east-west component is no longer evident and discriminant function analysis shows an increased misclassification of adjacent taxa previously differentiated by size. This demonstrates the east-west component of shape variation is underpinned by skull size, while the north-south axis is not. The latter axis is explicable in phylogenetic terms: baboons arose in Southern Africa and colonised East and West Africa to the north, diverging in the process, aided by climate-mediated isolating mechanisms. Environmental terms appear poorly correlated with shape variation compared with geography. This might indicate that there is no simple environment-morphology association, but certainly demonstrates that phylogenetic history is an overbearing factor in baboon morphological variation.

Stable isotopes provide independent support for the use of mesowear variables for inferring diets in African antelopes

We examine the relationship between mesowear variables and carbon and nitrogen isotopes in 16 species of African antelope (Mammalia: Bovidae). We show significant differences in carbon and nitrogen isotope values between individuals exhibiting sharp versus round cusps, and high versus low occlusal relief. We show significant correlations between mesowear variables and both carbon and nitrogen isotopes. We find significant correlations between mesowear score and nitrogen, but not carbon isotopes. Finally, we find no significant correlations between hypsodonty index and either isotope examined. Our results provide strong support for the use of mesowear variables in palaeodietary reconstructions of antelopes. Our results further suggest that for the antelopes examined here, mesowear signals are a direct result of diet, while hyposodonty may be the result of phylogenetic legacy.

Multi-tissue analysis of oxygen isotopes in wild rhesus macaques (Macaca mulatta)

Oxygen isotopes in animal tissues are directly related to body water composition and thus the environment. Accurate measurement of animal tissue δ(18)O provides information about local climate, an animal's geographical origin and subsequent movements, with wide applications in palaeobiology and forensic science. The genesis and evolution of tissue-based oxygen isotopes within species and within individuals are complex. We present the first data, for non-human primates, rhesus macaques (Macaca mulatta), on the relationship between oxygen isotope sources in bio-apatite (PO(4) and PCO(3)) and hair taken from six sample sites in Asia, ranging from western India to northern Vietnam. The range of values is similar within each tissue type, with good correlation between tissues (r = 0.791 to 0.908), allowing cross-tissue extrapolations. This is important when the availability of suitable tissues is limited. Biological interpretation of the small data set is difficult: macaque diets are eclectic, and the samples are from various locations. However, factors such as overall climate, precipitation quantity and source, and altitude are clearly influencing the results for each discrete geographical grouping. Future work could be aimed at assessing δ(18)O tissue associations for other species as the relationships appear to be species-specific.

What do medical students understand by research and research skills? Identifying research opportunities within undergraduate projects

BACKGROUND

Undergraduate research exposure leads to increased recruitment into academic medicine, enhanced employability and improved postgraduate research productivity. Uptake of undergraduate research opportunities is reported to be disappointing, and little is known about how students perceive research.

AIM

To investigate opportunities for undergraduate participation in research, recognition of such opportunities, and associated skills development.

METHOD

A mixed method approach, incorporating student focus and study groups, and documentary analysis at five UK medical schools.

RESULTS

Undergraduates recognised the benefits of acquiring research skills, but identified practical difficulties and disadvantages of participating. Analysis of 905 projects in four main research skill areas - (1) research methods; (2) information gathering; (3) critical analysis and review; (4) data processing - indicated 52% of projects provided opportunities for students to develop one or more skills, only 13% offered development in all areas. In 17%, project descriptions provided insufficient information to determine opportunities. Supplied with information from a representative sample of projects (n = 80), there was little consensus in identifying skills among students or between students and researchers. Consensus improved dramatically following guidance on how to identify skills.

CONCLUSIONS

Undergraduates recognise the benefits of research experience but need a realistic understanding of the research process. Opportunities for research skill development may not be obvious. Undergraduates require training to recognise the skills required for research and enhanced transparency in potential project outcomes.

Modern macaque dietary heterogeneity assessed using stable isotope analysis of hair and bone

Dietary variability might have been a major factor in the dispersal and subsequent persistence of the genus Macaca in both tropical and temperate areas. Macaques are found from northern Africa to Japan, yet there have been few systematic attempts to compare diets between different modern populations. Here we have taken a direct approach and sampled museum-curated tissues (hair and bone) of Macaca mulatta (rhesus macaques) for carbon and nitrogen stable isotope dietary analyses. Samples from India, Vietnam, and Burma (Myanmar) were taken, representing both tropical and temperate populations. The delta(13)C values obtained from hair show that the temperate macaques, particularly those from Uttar Pradesh, have a delta(13)C signature that indicates at least some use of C(4) resources, while the tropical individuals have a C(3)-based diet. However, delta(13)C values from bone bioapatite indicate a C(3)-based diet for all specimens and they do not show the C(4) usage seen in the hair of some animals, possibly because bone represents a much longer turnover period than that of hair. The results of delta(15)N analyses grouped animals by geographic region of origin, which may be related to local soil nitrogen values. The greatest variation in delta(15)N values was seen in the specimens from Burma, which may be partly due to seasonality, as specimens were collected at different times of year. We also investigated the relationship between the hair, bone collagen, and bone bioapatite delta(13)C results, and found that they are highly correlated, and that one tissue can be used to extrapolate results for another. However, our results also suggest that hair may pick up discrete feeding traces (such as seasonal usage), which are lost when only bone collagen and bioapatite are examined. This has important implications for dietary reconstructions of archaeological and paleontological populations.

The environmental context of human evolutionary history in Eurasia and Africa

This review has three main aims: (1) to make specific predictions about the habitat of the hypothetical last common ancestor of the chimpanzee/bonobo-human clade; (2) to outline the major trends in environments between 8-6 Ma and the late Pleistocene; and (3) to pinpoint when, and in some cases where, human ancestors evolved to cope with the wide range of habitats they presently tolerate. Several lines of evidence indicate that arboreal environments, particularly woodlands, were important habitats for late Miocene hominids and hominins, and therefore possibly for the last common ancestor of the chimpanzee/bonobo-human clade. However, as there is no clear candidate for this last common ancestor, and because the sampling of fossils and past environments is inevitably patchy, this prediction remains a working hypothesis at best. Nonetheless, as a primate, it is expected that the last common ancestor was ecologically dependent on trees in some form. Understanding past environments is important, as palaeoenvironmental reconstructions provide the context for human morphological and behavioural evolution. Indeed, the impact of climate on the evolutionary history of our species has long been debated. Since the mid-Miocene, the Earth has been experiencing a general cooling trend accompanied by aridification, which intensified during the later Pliocene and Pleistocene. Numerous climatic fluctuations, as well as local, regional and continental geography that influenced weather patterns and vegetation, created hominin environments that were dynamic in space and time. Behavioural flexibility and cultural complexity were crucial aspects of hominin expansion into diverse environments during the Pleistocene, but the ability to exploit varied and varying habitats was established much earlier in human evolutionary history. The development of increasingly complex tool technology facilitated re-expansion into tropical forests. These environments are difficult for obligate bipeds to negotiate, but their exploitation was accomplished by archaic and/or anatomically modern humans independently in Africa and south-east Asia. Complex social behaviour and material culture also allowed modern humans to reach some of the most hostile regions of the globe, above the Arctic Circle, by the late Pleistocene. This, with colonization of the Americas and Australasia, established Homo sapiens as a truly cosmopolitan species.

Environmental Correlates of the Cercopithecoid Radiations

Modern Old World monkeys live in an array of habitats, an ability that was established early in their evolutionary history. The Old World monkey radiation is commonly correlated with the general trend of climatic cooling in the Neogene and the associated increase in open habitats. However, although they became more abundant and speciated extensively in the very late Miocene, Pliocene and Pleistocene, many of the major events in cercopithecoid evolution occurred before the onset of the late Miocene long cooling period. In the Plio-Pleistocene, regional environmental change and interspecific competition probably influenced the radiations of the Old World monkeys in Africa much more than did global climatic patterns. In southern Africa, the evolution of the monkey community is tied to Pleistocene increases in grassland and open habitats. In East Africa, the more diverse cercopithecid fauna reflects the presence of a wider variety of habitats, including forest, woodland and grassland.

Muzzle size, paranasal swelling size and body mass in Mandrillus leucophaeus

The drill (Mandrillus leucophaeus), a forest-living Old World monkey, is highly sexually dimorphic, with males exhibiting extreme secondary sexual characteristics, including growth of paranasal swellings on the muzzle. In this study, the size of the secondary bone that forms the paranasal swellings on the muzzles of drills was assessed in relation to body mass proxies. The relationship between the overall size of the muzzle and surrogate measures of body mass was also examined. In female drills, muzzle breadth was positively correlated with two proxies of overall body mass, greatest skull length and upper M1 area. However, there was no such correlation in males. Paranasal swellings in males also appeared to have no significant relationship to body mass proxies. This suggests that secondary bone growth on the muzzles of male drills is independent of overall body size. Furthermore, this secondary bone appears to be vermiculate, probably developing rapidly and in an irregular manner, with no correlation in the sizes of paranasal swelling height and breadth. However, various paranasal swelling dimensions were related to the size of the muzzle. It is suggested that the growth of the paranasal swellings and possibly the muzzle could be influenced by androgen production and reflect testes size and sperm motility. The size and appearance of the paranasal swellings may thus be an indicator of reproductive quality both to potential mates and male competitors. Further work is required to investigate the importance of the paranasal swellings as secondary sexual characteristics in Mandrillus and the relationship between body size and secondary sexual characteristics. Attention should also be paid to the mechanisms and trajectories of facial growth in Mandrillus.

Large mammal turnover in Africa and the Levant between 1.0 and 0.5 Ma

Faunal change at the Early-Middle Pleistocene boundary in Europe has long been a topic for discussion. However, analyses of large mammal turnover at this time in Africa have been lacking, largely because of the low number of sites dated to this interval. Recent work, particularly in the last 10 years, has resulted in a much larger published sample of sites and we synthesize these data in this paper. In our multivariate (TWINSPAN) analyses of African and Levantine large mammal faunas we found that localities were subdivided by geographic regions, not by age. There were some small-scale changes with the appearance or extinction of particular taxa, but there was no large-scale turnover such as that seen in Europe. The Levant was included as a possible route for faunal interchange with east Africa, but no similarities were found between these areas. It therefore appears that the modern zoogeographic separation of the Levant and north Africa into the Palaearctic region and sub-Saharan Africa into the African region can be traced back to at least the Early-Middle Pleistocene boundary.

A reappraisal of the locomotion and habitat preference of Theropithecus oswaldi

The one modern member of the genus Theropithecus, T. gelada (Primates, Cercopithecidae), inhabits grassland and is highly terrestrial. It is often supposed that Theropithecus oswaldi, one of the most common primates of the Plio-Pleistocene of East and southern Africa, was also a highly terrestrial open habitat species. Ecomorphic analysis was used to assess the locomotor strategy and habitat preference of T. oswaldi, and it was found that this species was unlikely to have had a locomotor strategy and habitat preference identical to that of T. gelada, with T. oswaldi possibly using arboreal substrates in a manner similar to some modern baboon groups. Thus, it appears that there has been considerable ecological diversity in the genus Theropithecus over the course of its evolution, mirroring the diversity evident in the hominin fossil record.

Surgical landmarks for the proximal portion of the axillary nerve

OBJECT

The proximal segment of the axillary nerve (ANp) is often difficult to identify without extensive dissection deep into the axilla. The present study was performed to find reliable surgical landmarks for this nerve.

METHODS

Thirty dissections of human cadavers were performed to determine the relationships between the ANp and specific anatomical structures. The authors found that the ANp is consistently located within an anatomical triangle constructed by lines passing between the coracobrachialis and pectoralis minor muscles and the axillary artery. In addition, the ANp was routinely found 4 cm distal to the coracoid process of the scapula.

CONCLUSIONS

These findings should assist the surgeon in locating the ANp during brachial plexus reconstruction.