Lifestyle and patterns of physical activity in Hadza foragers

Objectives

Physically active lifestyles are associated with several health benefits. Physical activity (PA) levels are low in post-industrial populations, but generally high throughout life in subsistence populations. The Hadza are a subsistence-oriented foraging population in Tanzania known for being physically active, but it is unknown how recent increases in market integration may have altered their PA patterns. In this study, we examine PA patterns for Hadza women and men who engage in different amounts of traditional foraging.

Materials and Methods

One hundred and seventy seven Hadza participants (51% female, 19–87 years) wore an Axivity accelerometer (dominant wrist) for ~6 days during dry season months. We evaluated the effects of age, sex, and lifestyle measures on four PA measures that capture different aspects of the PA profile.

Results

Participants engaged in high levels of both moderate-intensity PA and inactivity. Although PA levels were negatively associated with age, older participants were still highly active. We found no differences in PA between participants living in more traditional “bush” camps and those living in more settled “village” camps. Mobility was positively associated with step counts for female participants, and schooling was positively associated with inactive time for male participants.

Conclusions

The similarity in PA patterns between Hadza participants in different camp types suggests that high PA levels characterize subsistence lifestyles generally. The sex-based difference in the effects of mobility and schooling on PA could be a reflection of the Hadza's gender-based division of labor, or indicate that changes to subsistence-oriented lifestyles impact women and men in different ways.

     

Comparative life history patterns of female gorillas

Objectives

Several theories have been proposed to explain the impact of ecological conditions on differences in life history variables within and between species. Here we compare female life history parameters of one western lowland gorilla population (Gorilla gorilla gorilla) and two mountain gorilla populations (Gorilla beringei beringei).

Materials and Methods

We compared the age of natal dispersal, age of first birth, interbirth interval, and birth rates using long-term demographic datasets from Mbeli Bai (western gorillas), Bwindi Impenetrable National Park and the Virunga Massif (mountain gorillas).

Results

The Mbeli western gorillas had the latest age at first birth, longest interbirth interval, and slowest surviving birth rate compared to the Virunga mountain gorillas. Bwindi mountain gorillas were intermediate in their life history patterns.

Discussion

These patterns are consistent with differences in feeding ecology across sites. However, it is not possible to determine the evolutionary mechanisms responsible for these differences, whether a consequence of genetic adaptation to fluctuating food supplies (“ecological risk aversion hypothesis”) or phenotypic plasticity in response to the abundance of food (“energy balance hypothesis”). Our results do not seem consistent with the extrinsic mortality risks at each site, but current conditions for mountain gorillas are unlikely to match their evolutionary history. Not all traits fell along the expected fast-slow continuum, which illustrates that they can vary independently from each other (“modularity model”). Thus, the life history traits of each gorilla population may reflect a complex interplay of multiple ecological influences that are operating through both genetic adaptations and phenotypic plasticity.

     

Assessing the association of skeletal indicators of stress with mean age-at-death in sub-adults

Objectives

The present study investigated the association of skeletal indicator of stress presence with mean age-at-death as a means of understanding whether commonly studied indicators are indeed indicative of increased frailty.

Materials and Methods

Using a medieval Gaelic population from Ballyhanna (Co. Donegal), the present study assessed the association between skeletal indicators of stress and mean age-at-death using the Kaplan–Meier survival function with log rank test to determine whether these indicators were associated with younger age-at-death, and therefore increased frailty, in sub-adults only (0 to 18 years, N = 139) and through comparison to an all-ages cohort (N = 318).

Results

Only linear enamel hypoplasia was found to be associated with significantly decreased survivorship across the all-ages cohort but, conversely, was associated with increased survivorship when analysis was restricted to sub-adults. All other indicators assessed were associated with increased age-at-death for both all-age cohorts and sub-adult cohorts (cribra orbitalia), increased age-at-death when assessing all ages only (porotic hyperostosis and healed periosteal lesions); or were sufficiently rare in adults to prevent comparative analysis (stunting and micronutrient deficiency). Increased survivorship in individuals with higher numbers of co-morbid skeletal indicators was observed for both sub-adults alone and all age cohort.

Discussion

These findings suggest that these commonly recorded skeletal indicators may be more accurately viewed simply as records of stressor exposure and subsequent survival only, rather than providing evidence that these sub-adults are frailer than their similarly aged-at-death peers. Thus, the demographic and sociocultural context is essential to the interpretation of observed skeletal indicators of stress.

     

Paleoepidemiology of cribra orbitalia: Insights from early seventh millennium BP Con Co Ngua,Vietnam

Objectives

We test the hypothesis that the condition(s) leading to the development of cribra orbitalia at Con Co Ngua, an early seventh millennium sedentary foraging community in Vietnam, effectively reduced the resilience of the population to subsequent health/disease impacts. An assessment of both the implications and potential etiology of cribra orbitalia in this specific population is carried out.

Methods

The effective sample included 141 adults aged ≥15 years (53 females, 71 males, and 17 unknown sex) and 15 pre-adults aged ≤14 years. Cribra orbitalia was identified by way of cortical bone porosity of the orbital roof initiated within the diplöic space, rather than initiated subperiosteally. The approach is also robust to the misidentification of various pseudo-lesions. Resultant data was analyzed using Kaplan–Meier survival analysis.

Results

Median survival is higher in adults aged ≥15 years without cribra orbitalia than those with this lesion. For the pre-adult cohort, the opposite pattern is seen where median survival is higher in those with cribra orbitalia than those without.

Conclusion

Adults displayed increased frailty and pre-adults increased resilience with respect to cribra orbitalia. The differential diagnosis for a survival analysis of adults and pre-adults with and without cribra orbitalia included iron deficiency anemia and B12/folate deficiency, parasitism (including hydatid disease and malaria) in addition to thalassemia. The most parsimonious explanation for observed results is for both thalassemia and malaria being the chief etiological agents, while appreciating these conditions interact with, and can cause, other forms such as hematinic deficiency anemias.

     

Human energetic stress associated with upregulation of spatial cognition

Objectives

Evolutionary life history theory has a unique potential to shed light on human adaptive capabilities. Ultra-endurance challenges are a valuable experimental model allowing the direct testing of phenotypic plasticity via physiological trade-offs in resource allocation. This enhances our understanding of how the body prioritizes different functions when energetically stressed. However, despite the central role played by the brain in both hominin evolution and metabolic budgeting, cognitive plasticity during energetic deficit remains unstudied.

Materials

We considered human cognitive plasticity under conditions of energetic deficit by evaluating variability in performance in three key cognitive domains. To achieve this, cognitive performance in a sample of 48 athletes (m = 29, f = 19) was assessed before and after competing in multiday ultramarathons.

Results

We demonstrate that under conditions of energetic deficit, performance in tasks of spatial working memory (which assessed ability to store location information, promoting landscape navigation and facilitating resource location and calorie acquisition) increased. In contrast, psychomotor speed (reaction time) remained unchanged and episodic memory performance (ability to recall information about specific events) decreased.

Discussion

We propose that prioritization of spatial working memory performance during conditions of negative energy balance represents an adaptive response due to its role in facilitating calorie acquisition. We discuss these results with reference to a human evolutionary trajectory centred around encephalisation. Encephalisation affords great plasticity, facilitating rapid responses tailored to specific environmental conditions, and allowing humans to increase their capabilities as a phenotypically plastic species.

     

Mapping bone microstructure trace element composition: Sr,Ba, Cu,and Pb in an early modern Danish skeleton

Objectives

A Geographical Information System (GIS) approach enhances the acquisition, management, and analysis of trace element data from cortical bone. A high-resolution spatial dimension expands the research potential of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) data from cortical bone cross-sections. The chemical characterization of hundreds of osteons, notably sequences of superimposed osteons, permits more exacting studies of individual life histories than is possible with analyses of bulk bone samples.

Methods

A GIS procedure was used to estimate Sr, Ba, Pb, and Cu concentrations, originally generated through LA-ICP-MS, for bone microstructural features, notably fragmentary and intact osteons, in a human femoral cross-section. The skeleton is from Ribe, Denmark, and dates to the early modern period.

Results

Postmortem chemical alteration was limited to the bone's outer and inner margins. Two dietary indicators, Sr and Ba, and two socioeconomic indicators, Pb and Cu, measured for individual osteons were correlated with one another. Osteon sequences indicate concentrations of all four elements increased late in life for this individual.

Conclusions

The application of GIS procedures expedites fine-grained analyses of variation in the distribution of trace elements in bone microstructure identifiable in cortical bone cross-sections. It provides an efficient means of extracting the most information possible from LA-ICP-MS data about the lives of people in the past. Combining the two procedures makes it easier to track exposure to elements such as Pb across the part of an individual's life represented by osteon sequences.

     

Biological normalcy and body fat: Obesity prevalence,fat stigma,and allostatic load among late adolescents and young adults

Objectives

Biological normalcy provides a framework to assess tensions between clinical definitions of “normal,” statistical norms, and normative beliefs. A prevailing cultural belief is obesity directly causes poor health, but research has demonstrated consequences of fat stigma. Previous research linked fat stigma and allostatic load (AL) in adults, but this has not been demonstrated in youth, and the role of obesity prevalence is unknown. This study assesses the relationship between fat stigma and AL among youth from counties varying by obesity prevalence.

Materials and methods

Undergraduates from 38 counties across the US state of Indiana (n = 175) were recruited. Fat stigma was measured using the brief stigmatizing situations inventory (SSI). AL was calculated using eight biomarkers representing cardiovascular, metabolic, and immune function. Poisson regression assessed relationships of interest and adjusted for potential confounding. An interaction term and stratified analyses were used to assess moderation.

Results

SSI was not statistically associated with obesity prevalence (RR = 0.96, p = 0.173) but did statistically significantly predict AL (RR = 1.019, p = 0.045) when adjusting for confounders. Obesity prevalence moderated the relationship between SSI and AL (RR = 0.993, p = 0.001).

Discussion

Results suggest that fat stigma, regardless of body fat percentage, is associated with physiologic wear and tear on the late adolescent body, and that exposure to obesity during earlier adolescence moderates this relationship. Those most at risk for high AL reported high fat stigma and lived in counties with relatively low obesity prevalence during earlier adolescence, suggesting vulnerability to fat stigma may be heightened where obesity is less common.

     

Some orangutans acquire enamel defects at regular intervals,but not according to seasonal cycles

Objectives

Developmental defects of tooth enamel are associated with systemic physiological stress and have been linked to seasonal environmental factors such as rainfall, temperature, and fruit availability. Here, we evaluate whether linear enamel hypoplasia and accentuated perikymata occur with any cyclicity on lower canines and then whether cycles differ between Bornean and Sumatran orangutans.

Materials and Methods

Epoxy casts of lower canines from Pongo abelii (n = 14) and P. pygmaeus (n = 33) were evaluated for perikymata and dental enamel defects. Individual developmental sequences (IDSs) were generated for each canine, tracking the position of each defect in the context of continuous perikymata (time). Autocorrelation, a form of time-series statistical analysis was run for each canine to identify whether any cyclicity of defect expression was discernable.

Results

Autocorrelation revealed cycles of defect expression within canines, but no common cycle periodicities were identified between individuals of the same species or across species. P. pygmaeus averaged more linear enamel hypoplasia per year than P. abelli, but no other comparisons (number of defects, number of perikymata between defects, and autocorrelation analysis) revealed differences between the species.

Discussion

Although no common patterns of defect expression were identified within or between P. abelli and P. pygmaeus, the potential for autocorrelation analysis is promising for primatological and paleoanthropological studies of seasonal phenomena.

     

The diploic venous system in Homo neanderthalensis and fossil Homo sapiens: A study using high-resolution computed tomography

Objectives

The diploic venous system has been hypothesized to be related to human brain evolution, though its evolutionary trajectory and physiological functions remain largely unclear. This study examines the characteristics of the diploic venous channels (DCs) in a selection of well-preserved Homo neanderthalensis and Upper Paleolithic Homo sapiens crania, searching for the differences between the two taxa and exploring the associations between brain anatomy and DCs.

Materials and Methods

Five H. neanderthalensis and four H. sapiens fossil specimens from Western Europe were analyzed. Based on Micro-CT scanning and 3D reconstruction, the distribution pattern and draining orifices of the DCs were inspected qualitatively. The size of the DCs was quantified by volume calculation, and the degree of complexity was quantified by fractal analyses.

Results

High-resolution data show the details of the DC structures not documented in previous studies. H. neanderthalensis and H. sapiens specimens share substantial similarities in the DCs. The noticeable differences between the two samples manifest in the connecting points surrounding the frontal sinuses, parietal foramina, and asterional area.

Discussion

This study provides a better understanding of the anatomy of the DCs in H. neanderthalensis and H. sapiens. The connection patterns of the DCs have potential utility in distinguishing between the two taxa and in the phylogenetic and taxonomic discussion of the Neandertal-like specimens with controversial taxonomic status.

     

BaYaka forager food sharing networks in the Congo Basin: The roles of gender homophily and kin sharing

Objectives

Food sharing is a costly form of cooperation that was likely critical to human evolutionary success, including the emergence of human's life history strategy. Food sharing in human communities may be maintained through a number of pathways, including direct dyadic reciprocity, reputation-based processes, and kin-biased exchange. Differences in reproductive demands, labor, and cultural norms may also result in gendered differences in cooperative networks. Here, we examine cooperative networks in egalitarian BaYaka foragers from the Congo Basin.

Materials and Methods

We collected social network data from 112 adults in 41 households in this subsistence community. We implement a Bayesian latent network model to assess individual-, dyadic-, and block-level predictors of food sharing partners.

Results

Conditioning on covariates, we found limited evidence for direct dyadic reciprocity in food sharing. Despite local norms regarding prestige avoidance, we found status-based homophily. High-status individuals—council members and local healers—were more likely to share with one another. Importantly, our results highlight gender differences in patterns of food sharing, interacting with genetic relatedness. Women were more likely to share with one another, especially with kin as genetic relatedness increased.

Discussion

Our results align with evolutionary framing emphasizing kin selection in costly cooperation. The results showing that women cooperate with other women, particularly kin, also complement sex-based patterns in some other mammalian species, potentially reflecting the social support necessary to manage reproductive costs and childcare. BaYaka women's subsistence productivity and local cultural dynamics for autonomy and egalitarianism may likewise help facilitate women's preferential cooperation with one another.

     

Estimating fertility using adults: A method for under-enumerated pre-adult skeletal samples

Objectives

Infant underrepresentation poses a great risk to accurate palaeodemographic findings when analyzing skeletal samples. Empirically derived palaeodemographic methods all require unbiased or minimally biased pre-adult representation for estimating demographic characteristics, including fertility. Currently, there are no reliable methods for estimating palaeodemographic parameters when pre-adults are underrepresented in skeletal samples, consequently such samples are often excluded from palaeodemographic analyses. The aim of this article is to develop a method for estimating total fertility rate (TFR) using reproductive aged adults, specifically for samples with suspected pre-adult under-enumeration.

Methodology

United Nations mortality data and TFR from the World Population Prospects was utilized. The correlation between known fertility and the proportion of individuals in key reproductive years (15–49 years) to total adult sample (15+ years) was assessed as an indirect means to estimate fertility.

Results

It was determined that the proportion of reproductive aged adults is a reasonable proxy for fertility. A significant positive correlation was observed between the TFR and those who died aged 15–49 years of age as a proportion of those who died ≥15 years (D15-49/D15+). SE of the estimate revealed reasonable predictive accuracy. When applied to two modern non-agricultural populations, the method showed some variability in accuracy but good potential for an improved outcome over existing methods when pre-adults are underrepresented.

Conclusion

This research has provided a new method for estimating fertility in archeological skeletal samples with pre-adult under-enumeration. In combination with a contextually focused approach, this provides a significant step toward further use of biased samples in palaeodemography.

     

Covariance in human limb joint articular morphology

Objectives

Limb synovial joints exhibit complex shapes that must accommodate often-antagonistic demands of function, mobility, and stability. These demands presumably dictate coordination among joint articular shapes, but the structure of morphological covariance within and among joints is unknown. This study analyzes the human shoulder, elbow, hip, and knee to determine how articular covariance is structured in relation to joint structure, accessory cartilage, and function.

Materials and Methods

Surface models were created from the CT scans of 200 modern skeletons from the University of Tennessee Donated Skeletal Collection. Three-dimensional landmarks were collected on the shoulder, elbow, hip, and knee joints. Two-block partial least squares were conducted to determine associations between surfaces of conarticular shapes, functionally analogous articulations, and articulations belonging to the same bone.

Results

Except for the components of the shoulder, all conarticular pairs exhibit covariance, though the strength of these relationships appears unrelated to the amount of accessory cartilage in the joint. Only the analogous articulations of the humerus and femur exhibit significant covariance, but it is unlikely that this pattern is due to function alone. Stronger covariance within the lower limb than the upper limb is consistent broader primate patterns of within-limb integration.

Discussion

With the exception of the elbow, complementary joint function does not appear to promote strong covariance between articulations. Analogous humeral and femoral surfaces are also serially homologous, which may result in the articular associations observed between these bones. Broadly, these patterns highlight the indirect relationship between joint congruence and covariance.

     

Stress exposure in specific growth periods associates with children's weight,height, and body mass index

Objectives

We investigate associations between children exposure to stressful events, considering: (1) the period in which the event took place, (2) the type of event, and (3) the cumulative effect of the events on children's weight, height and body mass index (BMI).

Methods

A total of 8429 Portuguese children (3349 exposed to at least one stressful event during their lifetime; 50.2% males; mean age = 7.21 ± 1.85 years) were included in the analysis. The occurrence of stressful (i.e., adverse) events was reported in a parental questionnaire; children's weight and height were objectively measured.

Results

When the stress event took place in the first 2 years of life, compared with during pregnancy or after the 2 years, children were shorter; but the association was weak and only significant for boys. After adjustment for child's birthweight, gestational age, breastfeeding duration, number of siblings, and father's education, the experience of 3+ stressful events (vs. 1 or 2) was associated with higher weight and height in boys. No interaction effect was found between stress and BMI.

Discussion

We found some evidence of associations between exposure to stressful events and physical growth of boys. We highlight the complex relationship between exposure to stressful experiences and children's physical growth, particularly the different effects of specific characteristics of the stress event and the sex differences.

     

Prenatal household size and composition are associated with infant fecal bacterial diversity in Cebu,Philippines

Objectives

The gut microbiome (GM) connects physical and social environments to infant health. Since the infant GM affects immune system development, there is interest in understanding how infants acquire microbes from mothers and other household members.

Materials and Methods

As a part of the Cebu Longitudinal Health and Nutrition Survey (CLHNS), we paired fecal samples (proxy for the GM) collected from infants living in Metro Cebu, Philippines at 2 weeks (N = 39) and 6 months (N = 36) with maternal interviews about prenatal household composition. We hypothesized that relationships between prenatal household size and composition and infant GM bacterial diversity (as measured in fecal samples) would vary by infant age, as well as by household member age and sex. We also hypothesized that infant GM bacterial abundances would differ by prenatal household size and composition.

Results

Data from 16 S rRNA bacterial gene sequencing show that prenatal household size was the most precise estimator of infant GM bacterial diversity, and that the direction of the association between this variable and infant GM bacterial diversity changed between the two time points. The abundances of bacterial families in the infant GM varied by prenatal household variables.

Conclusions

Results highlight the contributions of various household sources to the bacterial diversity of the infant GM, and suggest that prenatal household size is a useful measure for estimating infant GM bacterial diversity in this cohort. Future research should measure the effect of specific sources of household bacterial exposures, including social interactions with caregivers, on the infant GM.

     

The Neanderthal patellae from Krapina (Croatia): A comparative investigation of their endostructural conformation and distinctive features compared to the extant human condition

Objectives

The Neanderthal patella differs from that of extant humans by being thicker anteroposteriorly and by having more symmetric medial and lateral articular facets. However, it is still unclear to what extent these differences affect knee kinesiology. We aim at assessing the endostructural conformation of Neanderthal patellae to reveal functionally related mechanical information comparatively to the extant human condition. In principle, we expect that the Neanderthal patella (i) shows a higher amount of cortical bone and (ii) a trabecular network organization distinct from the extant human condition.

Materials and Methods

By using micro-focus X-ray tomography, we characterized the endostructure of six adult patellae from the OIS 5e Neanderthal site of Krapina, Croatia, the largest assemblage of human fossil patellae assessed so far, and compared their pattern to the configuration displayed by a sample of 22 recent humans.

Results and Discussion

The first expectation is rejected, indicating that the patellar bone might have not followed the trend of generalized gracilization of the human postcranial skeleton occurred through the Upper Pleistocene. The second prediction is at least partially supported. In Krapina the trabecular network differs from the comparative sample by showing a higher medial density and by lacking a proximal reinforcement. Such conformation indicates similar load patterns exerted in Neanderthals and extant humans by the vastus lateralis, but not by the vastus medialis, with implications on the mediolateral stabilization of the knee joint. However, the patterns of structural variation of the patellar network remain to be assessed in other Neanderthal samples.

     

Phylogeographic history of mitochondrial haplogroup J in Scandinavia

Background

Mitochondrial DNA haplogroup J is the third most frequent haplogroup in modern-day Scandinavia, although it did not originate there. To infer the genetic history of haplogroup J in Scandinavia, we examined worldwide mitogenome sequences using a maximum-likelihood phylogenetic approach.

Methods

Haplogroup J mitogenome sequences were gathered from GenBank (n = 2245) and aligned against the ancestral Reconstructed Sapiens Reference Sequence. We also analyzed haplogroup J Viking Age sequences from the European Nucleotide Archive (n = 54). Genetic distances were estimated from these data and projected onto a maximum likelihood rooted phylogenetic tree to analyze clustering and branching dates.

Results

Haplogroup J originated approximately 42.6 kya (95% CI: 30.0–64.7), with several of its earliest branches being found within the Arabian Peninsula and Northern Africa. J1b was found most frequently in the Near East and Arabian Peninsula, while J1c occurred most frequently in Europe. Based on phylogenetic dating, subhaplogroup J1c has its early roots in the Mediterranean and Western Balkans. Otherwise, the majority of the branches found in Scandinavia are younger than those seen elsewhere, indicating that haplogroup J dispersed relatively recently into Northern Europe, most plausibly with Neolithic farmers.

Conclusions

Haplogroup J appeared when Scandinavia was transitioning to agriculture over 6 kya, with J1c being the most common lineage there today. Changes in the distribution of haplogroup J mtDNAs were likely driven by the expansion of farming from West Asia into Southern Europe, followed by a later expansion into Scandinavia, with other J subhaplogroups appearing among Scandinavian groups as early as the Viking Age.

     

The rise of coastal Middle Bronze Age Levant – A multidisciplinary approach for investigating in Sidon,Lebanon

Objectives

The Levantine Middle Bronze Age (MBA, circa 2000–1500 BCE) marks a period of increased trade and regional interaction, spurred on by technological developments. In light of previous research exhibiting limited mobility in Sidon, further investigation was conducted using biodistance analysis to understand local population history and site development.

Materials and Methods

Dental nonmetric traits, a proxy for genetic information, were explored using ASUDAS on a sub-sample of primary inhumations (n = 35). The biodistance matrix was generated using Gower distance measures, and further tested using PERMDISP, PERMANOVA, Mantel test and hierarchical cluster analysis. The data was also contrasted to ⁸⁷Sr/⁸⁶Sr and δ¹⁸O as well as δ¹³C and δ¹⁵N values.

Results

There were no significant diachronic differences in isotopes values, and there was biological continuity (n = 35, Mantel test r = 0.11, p = 0.02, comparing local phases and biodistance). The analysis also suggested of a sub-group of individuals with biological proximity shared a more limited range of mobility and dietary habits.

Conclusions

The isotopes (⁸⁷Sr/⁸⁶Sr, δ¹⁸O, δ¹³C, δ¹⁵N) and biodistance analysis conducted on the Sidon College site skeletal assemblage exhibits stability and continuity of the people, despite the site's increasing role in the maritime network. This continuity may have been a key factor in Sidon's success, allowing it to accumulate wealth and resources for centuries to come.

     

Climbing influences entheseal morphology in the humerus of mice: An experimental application of the VERA methodology

Objectives

When studying hominin skeletal remains, anthropologists commonly assume that the morphology of entheses (muscle and tendon attachment sites) is influenced by physical activity patterns during life. Here, we use samples of mice from a prior experiment (Siegel & Jones [1975] American Journal of Physical Anthropology 42:141–144) to test this assumption. Specifically, we investigate the effects of habitual climbing on entheses of the humerus using a recently developed protocol for analyzing entheseal morphology called the “Validated Entheses-based Reconstruction of Activity” (VERA) method.

Materials and Methods

In the original experiment, young mice were raised for approximately 9 weeks in one of two experimental conditions: a cage designed to limit locomotion to terrestrial quadrupedalism over a flat surface (n = 22), or a cage designed to impel animals to cling to a suspended wire mesh apparatus and limit their locomotion to climbing (n = 21). We μCT-scanned the humeri of these mice and used the VERA method to assess the morphology of the deltoid tuberosity, greater tubercle, lesser tubercle, and supinator crest.

Results

Significant differences in entheseal morphology were detected between climbers and non-climbers when using both multivariate statistics to assess all entheses simultaneously and univariate statistics to assess each enthesis individually.

Discussion

Our results provide new support for the general use of entheseal morphology for inferring hominin physical activity patterns in the past. Furthermore, based on our results, we propose that analyzing entheseal morphology using the VERA method may be a promising strategy for future research on the importance of climbing in hominin locomotor evolution.

     

Tooth chipping patterns in Archaeolemur provide insight into diet and behavior

Objectives

Archaeolemur is a recently extinct genus of lemur that is often compared to some Cercopithecidae, especially baboons. This is due in part to their derived dentition, with large anterior teeth and reduced bilophodont molars. Research involving comparative morphology, analysis of coprolites, isotopes, and enamel structure, have suggested Archaeolemur had an omnivorous diet involving mechanically challenging items. Yet, microwear analysis of posterior teeth does not necessarily support this conclusion.

Materials and Methods

In this macroscopic study, dental chipping was recorded on permanent teeth of Archaeolemur from different localities (53 individuals; 447 permanent teeth; including both A. edwardsi and A. majori specimens). This study aimed to compare chipping patterns across the dentition of Archaeolemur with chipping in other primates.

Results

The results show enamel chipping was prevalent on the anterior teeth of Archaeolemur (38.9% of anterior teeth showed at least one fracture) yet rare in posterior teeth (9%). There was a decrease in chipping frequency across the dentition, moving distally from incisors (50%; 20/40), through caniniform teeth (30%; 15/50), premolars (9.5%; 16/169), and molars (8.5%; 16/188).

Discussion

The results support previous research suggesting Archaeolemur had a varied omnivorous diet in which the anterior dentition was used for extensive food processing. This likely included mechanically challenging items such as tough/hard large fruits, small vertebrates, and crustaceans. Such a high rate of chipping in the anterior dentition is uncommon in other primates, with exception of hominins.