Jason S. Massey

Postcranial skeletal proportions in living apes have been linked to patterns of arboreal behaviors within and between populations, offering a comparative baseline for interpreting arboreal behavior in fossil hominoids. We quantified metatarsal and proximal phalangeal lengths across all five pedal rays in Gorilla , comparing western lowland gorillas ( Gorilla gorilla gorilla ), low‐ and high‐elevation Grauer's gorillas ( Gorilla beringei graueri ), and two ecologically distinct mountain gorilla ( Gorilla beringei beringei ) populations: those of Bwindi Impenetrable National Park, Uganda, and the Virunga Massif (Volcanoes National Park, Rwanda). The Bwindi sample, assembled from individuals recovered by the Mountain Gorilla Skeletal Project between 2017 and 2025, represents the first substantial pedal dataset for this population. After separately scaling element lengths by estimated body mass and hindlimb length, Bwindi gorillas' third and fourth metatarsal lengths fell consistently between those of the more arboreal western lowland and highly terrestrial Virunga gorillas, while proximal phalangeal and hallux lengths varied little across populations. Additionally, Virunga gorillas showed longer second metatarsals compared to other populations, a feature we link to their strongly terrestrial locomotor habits. In comparing relative manual and pedal element lengths from the same individuals, metacarpals were relatively longer than metatarsals across all populations in rays 2–5, with this pattern reversed in the hallux; among these, only the second ray showed a significant interpopulation difference, with western lowland gorillas exhibiting relatively longer metacarpals than all other groups. Though interpopulation differences in the lengths of pedal elements were generally weaker than those found in the manual elements of the same individuals, these findings suggest that habitat‐associated variation in foot morphology can be detected between populations of gorilla subspecies, underscoring the value of fine‐grained, population‐level skeletal comparisons for refining locomotor inference in the hominoid and hominin fossil record.

The integration of ultrasound imaging into preclinical anatomy teaching is often questioned with respect to its objective impact on anatomical knowledge. This study aimed to (i) evaluate short‐term knowledge gain following ultrasound‐integrated anatomy teaching, (ii) characterize students' perceptions of the learning experience, and (iii) assess the feasibility of delivery across rural, metropolitan, and international settings. Integrated ultrasound sessions were delivered to preclinical medical students in four settings (rural Australian graduate‐entry, metropolitan Australian direct‐entry, and metropolitan and rural Malaysian direct‐entry). Short‐term knowledge gain was assessed in the Australian rural cohort using a pretest‐posttest design with counterbalanced parallel forms, analyzed with linear mixed‐effects models. Student feedback underwent content analysis and feasibility was summarized using key implementation descriptors. In the short‐term knowledge gain study (103 students; 193 observed assessments), posttest performance was significantly higher than pretest performance ( adjusted mean difference 0.66 correct answers, 95% confidence interval [CI] 0.23–1.08; p = 0.003). Students reported benefits for in situ visualization, spatial understanding, and clinical relevance. Delivery was feasible at all four sites, including by videoconference where no local ultrasound unit was available. In conclusion, integrated ultrasound was feasible across diverse settings and, in the Australian rural cohort, was associated with higher assessment performance immediately after teaching. As the design had no parallel comparator, this finding indicates short‐term knowledge gain rather than a causal effect or long‐term retention. Together, these findings support ultrasound as a complementary preclinical tool, rather than being reserved solely for post‐curricular clinical skill acquisition.

Objectives: Craniofacial fluctuating asymmetry (FA) in gorillas has been linked to environmental and/or genetic stress. Prolonged population declines increase levels of inbreeding, leading to developmental instability, which can manifest as FA. Among gorillas studied to date, craniofacial FA levels are highest in mountain gorillas ( G. beringei beringei ) and lowest in western lowland gorillas ( G. gorilla gorilla ), reflecting known levels of genetic diversity and inbreeding in these subspecies. This study assessed craniofacial FA in Cross River gorillas ( G. gorilla diehli ), a little‐known subspecies with high levels of inbreeding due to a recent genetic bottleneck. Materials and Methods: Thirty fixed landmarks of the craniofacial skeleton were used to assess FA in 30 Cross River gorillas using Procrustes ANOVA. Principal component analysis assessed variation in both symmetric and asymmetric components. Differences in FA magnitudes between Cross River gorillas and published data for other Gorilla subspecies were assessed using permutation tests. Results: Craniofacial FA accounts for 9.9% of shape variation in Cross River gorillas, whereas directional asymmetry accounts for 0.5%. Allometry accounts for 14.1% of shape variation in the symmetric component and 3.8% in the asymmetric component. Craniofacial FA magnitudes are higher in Cross River gorillas than in western lowland gorillas and lower than in mountain gorillas. Discussion: High FA in Cross River gorillas aligns with known levels of inbreeding, supporting the link between genetic stress and craniofacial FA in gorillas. Persistent inbreeding and the loss of genetic diversity may decrease population fitness, further increasing the risk of extinction.

Neuroanatomy is notoriously challenging to learn and often contributes to “neurophobia.” Traditional instruction has relied on lectures and dissection, but newer pedagogical innovations are increasingly adopted. Despite this, comparative evidence to guide best practices is limited. This systematic review and meta‐analysis aimed to synthesize the literature on neuroanatomy teaching interventions, and quantitatively assess pooled effects on (1) short‐term knowledge retention, (2) long‐term knowledge retention, and (3) learner satisfaction. Following PRISMA guidelines, we searched PubMed, EMBASE, MEDLINE, Scopus, and Web of Science for studies published between January 2000 and February 2025. Eligible studies described defined neuroanatomy teaching interventions for post‐secondary learners. Those reporting knowledge or satisfaction outcomes were included in the meta‐analysis. Two reviewers independently performed screening, extraction, and methodological quality assessment using the MERSQI. Random‐effects meta‐analyses generated pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs). From 11,438 records, 195 studies met inclusion for qualitative synthesis, most often involving digital/web‐based applications ( n = 38), immersive technologies ( n = 22), or 3D models ( n = 18). Overall methodological quality was moderate. Students valued interventions promoting 3D reasoning, clinical integration, and active learning. Thirty‐seven studies contributed to meta‐analysis. Computer/web‐based applications showed consistent benefit for short‐term knowledge (SMD = 1.69; 95% CI [0.32, 3.06]). Evidence for long‐term knowledge retention and satisfaction was less robust. In conclusion, neuroanatomy education is shifting toward blended curricula integrating digital tools, models, and active pedagogies. Computer/web‐based applications are most consistently effective for short‐term learning; further research should emphasize long‐term outcomes.

“Neurophobia,” a fear of neural sciences, presents a significant impediment in medical education, contributing to student anxiety and influencing career selection away from neurological specialties. The high prevalence of neurophobia underscores the significance of this issue. Despite the widespread recognition of neurophobia, a clear mechanism for addressing this across healthcare curricula remains elusive. To help address this gap, this article describes the design and evaluation of an innovative, multimodal curriculum designed to target this deep‐seated fear of neuroanatomy. We hypothesized that this multimodal, gamified approach would increase the students' self‐perceived confidence in neuroanatomy. The curriculum was delivered to medical students at two different institutions, integrating traditional neuroanatomy teaching methods such as donor dissection with strategies that gamify learning. Gamification relied on low‐fidelity competitions, such as Memory Games, Neuro‐Charades, A Minute to Win It, “Neuro‐Jeopardy” revision sessions, clinically oriented simulated anatomy ward rounds, and an immersive escape room, many of which were developed with corresponding scalable digital versions for broad dissemination. A mixed‐methods evaluation using pre‐ and post‐course surveys and content analysis of qualitative feedback from medical students was conducted to assess their perceived confidence in neuroanatomy. A significant increase in mean self‐perceived learner confidence was observed post‐intervention (V = 489, p < 0.001). Quantitative and qualitative data indicated high student satisfaction and perceived educational efficacy for all curriculum components. Students affirmed the value of dissection for 3D conceptualization while highlighting how gamified activities fostered engagement and collaborative learning. This work suggests that a synergistic combination of traditional and innovative pedagogical techniques can help improve learner confidence in neuroanatomy. Further iterations of these interventions focused on a framework for scalability without compromising impact.

Primate mandibular morphology is often associated with jaw functionality of the masticatory complex in the context of variation in diets. Recent research into the disparities between the diet and jaw functionality in male and female hominoids is inconclusive and suggests that sexual dimorphism in the mandible may be influenced by external factors such as temporalis and masseter muscle morphology, which in turn may be influenced by sexual selection. As the muscles associated with mastication (i.e., the type of chewing exhibited by primates and other mammals) encompass the mandible as well as the neurocranium, including the sagittal crest among some individuals, this study investigates sex‐specific associations between regions of the mandibular ramus and neurocranium associated with mastication in a dentally mature sample of Gorilla and Pongo. A total of four cranial and mandibular variables were measured in two Gorilla taxa (Gorilla gorilla gorilla and Gorilla beringei graueri) and one Pongo taxon (Pongo pygmaeus pygmaeus) (n = 220). For all three taxa, we investigate (a) whether the degree of sexual dimorphism in cranial regions associated with sagittal cresting (sagittal crest size (SCS) and temporalis muscle attachment area (TMAA)) is proportional to the degree of mandibular ramus area (MRA) and coronoid process height (CPH) sexual dimorphism, (b) whether there are sex differences in scaling relationships between TMAA and MRA, and (c) whether there are sex differences in the strength of association between TMAA and CPH. We show that for G. g. gorilla, variables associated with sagittal cresting show higher sexual dimorphism values than our two mandibular ramus variables, which is not the case for G. b. graueri or for P. p. pygmaeus. All three taxa show similar sex‐specific scaling relationships between TMAA and MRA, where for males this relationship does not diverge from isometry, and for females there is a negative allometric relationship. Our findings also show intraspecific sex differences in allometric slopes between MRA and TMAA for all three taxa. Only G. g. gorilla shows a significant association between TMAA and CPH, which is observed in both sexes. Although there are some statistical associations between the cranial and mandibular regions associated with mastication, our results show that among male gorillas and orangutans, patterns of variation in the sagittal crest, TMAA, mandibular ramus and the coronoid process cannot be explained by the muscle attachment hypothesis alone. These findings have implications surrounding the associations between social behaviour and the morphology of the craniofacial complex.

Proper methods of assessment to objectively identify pain are essential for welfare improvements of piglets undergoing surgical castration on commercial farms. The Piglet Grimace Scale (PGS) is used to identify changes in facial expressions caused by acute pain in piglets undergoing tail docking and castration. However, subjective scoring methods are a concern for the validation of the PGS. The objectives of this study were to evaluate and refine the PGS through 3D landmark geometric morphometrics. Male piglets (n = 88) were randomly allocated to one of two treatments: castration and sham-castration. Piglet facial images were taken at four time points (before treatment, immediately post-treatment, 1 h post-treatment, and 4 h post-treatment) using a photogrammetry rig. Images were scored by four raters using five facial action units (FAUs): orbital tightening, ear position, temporal tension, lip contraction, and nose bulge/cheek tension. Three-dimensional facial models were generated and landmarked denoting 3 FAUs (orbital tightening, lip contraction, and nose bulge/cheek tension). Results suggest that orbital tightening and ear position may be reliable FAUs for the PGS. However, neither the PGS nor 3D landmark-based geometric morphometrics were able (both p > 0.10) to reliably identify facial indicators of pain in piglets undergoing castration.

The temporomandibular joint is the direct interface between the mandible and the cranium and is critical for transmitting joint reaction forces and determining mandibular range of motion. As a consequence, understanding variation in the morphology of this joint and how it relates to other aspects of craniofacial form is important for better understanding masticatory function. Here, we present a detailed three‐dimensional (3D) geometric morphometric analysis of the cranial component of this joint, the glenoid fossa, across a sample of 17 anthropoid primates, and we evaluate covariation between the glenoid and the cranium and mandible. We find high levels of intraspecific variation in glenoid shape that is likely linked to sexual dimorphism and joint remodeling, and we identify differences in mean glenoid shape across taxonomic groups and in relation to size. Analyses of covariation reveal strong relationships between glenoid shape and a variety of aspects of cranial and mandibular form. Our findings suggest that intraspecific variation in glenoid shape in primates could further be reflective of high levels of functional flexibility in the masticatory apparatus, as has also been suggested for primate jaw kinematics and muscle activation patterns. Conversely, interspecific differences likely reflect larger scale differences between species in body size and/or masticatory function. Results of the covariation analyses dovetail with those examining covariation in the cranium of canids and may be indicative of larger patterns across mammals.

Researchers using digital methods often collect data from 3D models at different resolutions, obtained using different scanning techniques. Although previous research has sought to understand whether scanning method and model resolution affect data accuracy, no study has systematically evaluated the sources of error associated with scanning method, data acquisition method and model resolution with the aim of providing practical recommendations about the model resolution required to yield sufficiently accurate data for specimens of given sizes. In this study, using data taken from primate specimens of three broad size categories, we test whether 3D models obtained using five different scanners (Breuckmann SmartSCAN, DAVID/HP 3D Pro S3, NextEngine 2020i, Creaform Go!Scan 20 and microCT/clinicalCT) yield accurate measurements. We assess whether caliper measurements can be used alongside measurements collected from 3D surface models, whether scanning resolution affects measurement accuracy, and how scan resolution, estimated using each scanner's proprietary software, compares to model resolution measured in a standardized way. Each scanner produces 3D models that yield accurate measurements for each size category, however, combining caliper data with those taken from digital models can be problematic. Our results indicate that the accuracy of measurements taken from 3D models depends on both object size and model resolution. Based on our findings, we recommend that small specimens should be scanned at <0.3 mm, medium specimens at 0.3–0.7 mm, and large specimens at 0.3–0.5 mm resolutions if data taken from 3D surface models are to be combined with caliper datasets. We further show, for the first time, that discrepancies in estimated final model resolution are frequently observed across software packages. We therefore recommend that researchers ensure that final model resolutions are adequate based on specimen size and are independently verified using a software package other than the scanner's proprietary software. Finally, we consider the implications of the findings that measurements obtained from surface models are variably consistent with those obtained using calipers.