Gradual decline in mobility with the adoption of food production in Europe

The effects of the industrial transition on lower limb bone structure: A comparison of the inhabitants of Pecos Pueblo and present-day Indigenous peoples of New Mexico

OBJECTIVES

Comparisons between Indigenous peoples over time and within a particular geographic region can shed light on the impact of environmental transitions on the skeleton, including relative bone strength, sexual dimorphism, and age-related changes. Here we compare long bone structural properties of the inhabitants of the late prehistoric-early historic Pecos Pueblo with those of present-day Indigenous individuals from New Mexico.

MATERIALS AND METHODS

Femora and tibiae of 126 adults from Pecos Pueblo and 226 present-day adults were included in the study. Cross-sectional diaphyseal properties-areas and second moments of area-were obtained from past studies of the Pecos Pueblo skeletal sample, and from computed tomography scans of recently deceased individuals in the present-day sample.

RESULTS

Femora and tibiae from Pecos individuals are stronger relative to body size than those of present-day Indigenous individuals. Present-day individuals are taller but not wider, and this body shape difference affects cross-sectional shape, more strongly proximally. The tibia shows anteroposterior strengthening among Pecos individuals, especially among males. Sexual dimorphism in midshaft bone shape is stronger within the Pecos Pueblo sample. With aging, Pecos individuals show more medullary expansion but also more subperiosteal expansion than present-day individuals, maintaining bone strength despite cortical thinning.

DISCUSSION

Higher activity levels, carried out over rough terrain and throughout adult life, likely explain the relatively stronger lower limb bones of the Pecos individuals, as well as their greater subperiosteal expansion with aging. Greater sexual dimorphism in bone structure among Pecos individuals potentially reflects greater gender-based differences in behavioral patterns.

Evolutionary and functional analyses of LRP5 in archaic and extant modern humans

BACKGROUND

The human lineage has undergone a postcranial skeleton gracilization (i.e. lower bone mass and strength relative to body size) compared to other primates and archaic populations such as the Neanderthals. This gracilization has been traditionally explained by differences in the mechanical load that our ancestors exercised. However, there is growing evidence that gracilization could also be genetically influenced.

RESULTS

We have analyzed the LRP5 gene, which is known to be associated with high bone mineral density conditions, from an evolutionary and functional point of view. Taking advantage of the published genomes of archaic Homo populations, our results suggest that this gene has a complex evolutionary history both between archaic and living humans and within living human populations. In particular, we identified the presence of different selective pressures in archaics and extant modern humans, as well as evidence of positive selection in the African and South East Asian populations from the 1000 Genomes Project. Furthermore, we observed a very limited evidence of archaic introgression in this gene (only at three haplotypes of East Asian ancestry out of the 1000 Genomes), compatible with a general erasing of the fingerprint of archaic introgression due to functional differences in archaics compared to extant modern humans. In agreement with this hypothesis, we observed private mutations in the archaic genomes that we experimentally validated as putatively increasing bone mineral density. In particular, four of five archaic missense mutations affecting the first β-propeller of LRP5 displayed enhanced Wnt pathway activation, of which two also displayed reduced negative regulation.

CONCLUSIONS

In summary, these data suggest a genetic component contributing to the understanding of skeletal differences between extant modern humans and archaic Homo populations.

Trabecular bone volume fraction in Holocene and Late Pleistocene humans

Research suggests that recent modern humans have gracile skeletons in having low trabecular bone volume fraction (BV/TV) and that gracilization of the skeleton occurred in the last 10,000 years. This has been attributed to a reduction in physical activity in the Holocene. However, there has been no thorough sampling of BV/TV in Pleistocene humans due to limited access to high resolution images of fossil specimens. Therefore, our study investigates the gracilization of BV/TV in Late Pleistocene humans and recent (Holocene) modern humans to improve our understanding of the emergence of gracility. We used microcomputed tomography to measure BV/TV in the femora, humeri and metacarpals of a sample of Late Pleistocene humans from Dolní Věstonice (Czech Republic, ∼26 ka, n = 6) and Ohalo II (Israel, ∼19 ka, n = 1), and a sample of recent humans including farming groups (n = 39) and hunter-gatherers (n = 6). We predicted that 1) Late Pleistocene humans would exhibit greater femoral and humeral head BV/TV compared with recent humans and 2) among recent humans, metacarpal head BV/TV would be greater in hunter-gatherers compared with farmers. Late Pleistocene humans had higher BV/TV compared with recent humans in both the femur and humerus, supporting our first prediction, and consistent with previous findings that Late Pleistocene humans are robust as compared to recent humans. However, among recent humans, there was no significant difference in BV/TV in the metacarpals between the two subsistence groups. The results highlight the similarity in BV/TV in the hand of two human groups from different geographic locales and subsistence patterns and raise questions about assumptions of activity levels in archaeological populations and their relationships to trabecular BV/TV.

Trabecular bone morphology in big cats reflects the complex diversity of limb use but not home range size or daily travel distance

A relationship exists between mechanical loading and bone morphology. Although studies show a relationship between trabecular bone morphology and locomotor strategy in mammals, none of them have studied trabecular bone morphology in felid species occupying disparate and overlapping habitats. We investigate trabecular bone volume fraction (BVF) in the femoral and humeral heads, and distal tibia of four felid species (mountain lions, jaguars, cheetahs, and leopards) to identify whether there is a relationship between BVF and locomotor behavior. This study's goals are to identify whether felid species with high daily travel distance or large home range size have greater BVF compared with those with small daily travel distance or home range size, and whether BVF is correlated among the three elements of the fore and hindlimb studied. We quantified BVF in micro- and peripheral computed tomography images and found no significant differences across species in the femoral and humeral head (p > 0.05). However, in the distal tibia, results showed that leopards, mountain lions, and cheetahs have significantly greater (p < 0.05) BVF than jaguars. Despite differences in home range size and daily travel distance, the proximal elements did not reflect differences in BVF; however, the distal-most element did, suggesting decreased loading among jaguars. These findings suggest that the observed pattern of trabecular bone morphology is potentially due to the diversity in locomotor strategy of the forelimb. Additionally, these results imply that neither home range size nor daily travel distance are clear indicators of activity levels. A cautious approach is warranted in studying how loading influences trabecular morphology.

Take a load off: skeletal implications of sedentism in the feet of modern body donors

Background and Objectives

Modern biocultural environments continue to place selective pressures on our skeletons. In the past century, a major cultural pressure has been the rise in sedentism. However, studies considering the effects of sedentism on the foot have largely considered pathological changes to the gross foot without particular regard for the pedal skeleton. To address this gap in the literature, temporal trends in the development of osteoarthritis and entheseal changes on the tarsals and metatarsals were analyzed in the context of biodemographic data for recent modern humans.

Methodology

The sample utilized for this project is comprised of 71 individuals from the William M. Bass Donated Skeletal Collection, with birth years ranging from 1909 to 1993. Temporal trends in osteoarthritis and entheseal changes were determined via ANCOVA, using year of birth as the explanatory variable and biodemographic variables (age, sex, stature, body mass index and tibial robusticity) as covariates.

Results

Results indicate that entheseal changes and osteoarthritis have decreased over time, and these trends are statistically significant. Temporal trends in pedal entheseal changes and osteoarthritis vary by sex.

Conclusions and Implications

The increase in sedentary behavior over time has usually been framed as a net negative for human health and well-being. However, considered in isolation, the decrease in entheseal changes and osteoarthritis presented here might be considered a positive development as they suggest overall less stress on the modern human foot. This study also has the potential to inform the health sciences and general public about biocultural contributors to modern foot health.

Multiproxy bioarchaeological data reveals interplay between growth, diet and population dynamics across the transition to farming in the central Mediterranean

The transition to farming brought on a series of important changes in human society, lifestyle, diet and health. The human bioarchaeology of the agricultural transition has received much attention, however, relatively few studies have directly tested the interrelationship between individual lifestyle factors and their implications for understanding life history changes among the first farmers. We investigate the interplay between skeletal growth, diet, physical activity and population size across 30,000 years in the central Mediterranean through a 'big data' cross-analysis of osteological data related to stature (n = 361), body mass (n = 334) and long bone biomechanics (n = 481), carbon (δ13C) and nitrogen (δ15N) stable isotopes (n = 1986 human, n = 475 animal) and radiocarbon dates (n = 5263). We present the observed trends on a continuous timescale in order to avoid grouping our data into assigned 'time periods', thus achieving greater resolution and chronological control over our analysis. The results identify important changes in human life history strategies associated with the first farmers, but also highlight the long-term nature of these trends in the millennia either side of the agricultural transition. The integration of these different data is an important step towards disentangling the complex relationship between demography, diet and health, and reconstruct life history changes within a southern European context. We believe the methodological approach adopted here has broader global implications for bioarchaeological studies of human adaptation more generally.

Selection and adaptation in human migration

This article reviews the ways migration shapes human biology. This includes the physiological and genetic, but also socio-cultural aspects such as organization, behavior, and culture. Across disciplines I highlight the multiple levels of cultural and genetic selection whereby individuals and groups adapt to pressures along a migration timeline: the origin, transit, and destination. Generally, the evidence suggests that selective pressures and adaptations occur at the individual, family, and community levels. Consequently, across levels there are negotiations, interactions, and feedbacks that shape migration outcomes and the trajectory of evolutionary change. The rise and persistence of migration-relevant adaptations emerges as a central question, including the maintenance of cumulative culture adaptations, the persistence of "cultures of migration," as well as the individual-level physiological and cognitive adaptations applied to successful transit and settlement in novel environments.

Inferring the mobility of a middle Upper Paleolithic female skeleton from Caviglione (Liguria, Italy): Impact of trauma and mountainous terrain

Mobility and territory occupation, the participation of injured individuals in group activities, and the role of women in early human groups are crucial issues in human evolution. Previously, a biomechanical study showed evidence of several traumas to the upper limb of the well-preserved middle Upper Paleolithic (UP) female skeleton from Caviglione (Caviglione 1, Liguria, Italy) but did not characterize their impact on locomotor behavior. Furthermore, mobility in the European UP context is thoroughly documented in males but not in females. Therefore, we examined whether this trauma-affected female skeleton shows bone adaptation to high mobility, as expected in UP groups, and to frequent foot eversion and inversion, as expected, given the mountainous area in which it was discovered. This study investigated the structural properties of the femur, tibia, fibula, and first metatarsal to infer the mobility level and pattern of Caviglione 1. We analyzed the diaphyseal 'shape', robusticity, fibular cortical distribution, and relative robusticity (fibula versus tibia). No substantial findings were derived from the first metatarsal. The fibular cortical distribution can discriminate 'active' (nomadic or settled) and recent sedentary human groups; these findings indicated Caviglione 1 belonged to the former. Interestingly, compared with ancient and recent sedentary humans and some UP individuals, Caviglione 1 had femurs with strong relative anteroposterior rigidity and robust tibias and fibulas reflecting an adaptation to extremely high levels of mobility. The very high relative fibular robusticity of Caviglione 1, higher than that of Middle UP males, is consistent with bone adaptation to frequent travel through mountainous terrain. Such fibular robusticity may also be a consequence of imbalance, due to upper limb traumas, when traveling downhill. These findings indicate that injured individuals may have participated in subsistence activities in past populations and describe an UP female with bone adaptations to habitual high mobility, notably in mountainous terrain.

Mandibular morphology and the Mesolithic-Neolithic transition in Westernmost Iberia

Neolithic farming and animal husbandry were first developed in the Near East ~ 10,000 BCE and expanded westwards, reaching westernmost Iberia no later than 5500 BCE. It resulted in major social, cultural, economic and dietary changes. Yet, the impact of this change on human mandibular morphology in Iberia is yet to be assessed, which is regrettable because mandible form is impacted by population history and diet. In this study we used Mesolithic to Chalcolithic Iberian samples to examine the impact of this transition on mandibular morphology. We also compared these samples with a Southern Levantine Chalcolithic population to assess their relationship. Lastly, we assessed dental wear to determine if the morphological differences identified were related to the material properties of the diet. We found differences between samples in mandibular shape but not size, which we attribute to contrasting population histories between Mesolithic and later populations. Some differences in the severity of dental wear were also found between Mesolithic and later Iberian samples, and smaller between the Mesolithic Iberians and southern Levantines. Little relationship was found between wear magnitude and mandibular shape. Altogether, our results show that the Mesolithic-Neolithic Iberian transition resulted in a meaningful change in mandibular morphology, which was likely driven more by population history than by dietary change.

Structural properties of the Late Pleistocene Liujiang femoral diaphyses from southern China

The characterization of the femoral diaphysis in Pleistocene hominins with chronoecogeographical diversity plays a crucial role in evaluating evolutionary shifts in locomotor behavior and body shape. However, Pleistocene hominin fossil remains in East Asia are scarce and are widely dispersed temporally and spatially, impeding our comprehension of the nature and polarity of morphological trends. Here, we present qualitative and quantitative analyses of the cross-sectional properties and structural organization of diaphyses in two Late Pleistocene hominin femora (Liujiang PA91 and PA92) from southern China, comparing them to other Eurasian and African Pleistocene hominins. By integrating surface features and internal structure, our findings reveal that the Liujiang femora exhibit modern human-like characteristics, including a developed pilaster, a gluteal buttress, and minimum mediolateral breadth located at the midshaft. The presence of a femoral pilaster may relate to posterior cortical reinforcement and an increased anteroposterior bending rigidity along the mid-proximal to mid-distal portion of the diaphysis. Compared to archaic Homo, Liujiang and other Late Pleistocene modern human femora show a thinner mediolateral cortex and lower bending rigidity than the anteroposterior axis, and a lack of medial buttress, potentially indicating functionally related alterations in a range of pelvic and proximal femoral features throughout the Pleistocene. The femoral robusticity of the Liujiang individual resembles that of other Pleistocene hunter-gatherers from East Asia, implying comparable overall mobility or activity levels. The investigation of Liujiang femoral diaphyseal morphology contributes to a more comprehensive understanding of early modern human postcranial structural morphology in East Asia.

The estimation and evolution of hominin body mass

Body mass is a critical variable in many hominin evolutionary studies, with implications for reconstructing relative brain size, diet, locomotion, subsistence strategy, and social organization. We review methods that have been proposed for estimating body mass from true and trace fossils, consider their applicability in different contexts, and the appropriateness of different modern reference samples. Recently developed techniques based on a wider range of modern populations hold promise for providing more accurate estimates in earlier hominins, although uncertainties remain, particularly in non-Homo taxa. When these methods are applied to almost 300 Late Miocene through Late Pleistocene specimens, the resulting body mass estimates fall within a 25-60 kg range for early non-Homo taxa, increase in early Homo to about 50-90 kg, then remain constant until the Terminal Pleistocene, when they decline.

Leveraging mice with diverse microbial exposures for advances in osteoimmunology

The skeletal and immune systems are intricately intertwined within the bone marrow microenvironment, a field of study termed osteoimmunology. Osteoimmune interactions are key players in bone homeostasis and remodeling. Despite the critical role of the immune system in bone health, virtually all animal research in osteoimmunology, and more broadly bone biology, relies on organisms with naïve immune systems. Drawing on insights from osteoimmunology, evolutionary anthropology, and immunology, this perspective proposes the use of a novel translational model: the dirty mouse. Dirty mice, characterized by diverse exposures to commensal and pathogenic microbes, have mature immune systems comparable to adult humans, while the naïve immune system of specific-pathogen free mice is akin to a neonate. Investigation into the dirty mouse model will likely yield important insights in our understanding of bone diseases and disorders. A high benefit of this model is expected for diseases known to have a connection between overactivation of the immune system and negative bone outcomes, including aging and osteoporosis, rheumatoid arthritis, HIV/AIDS, obesity and diabetes, bone marrow metastases, and bone cancers.

A new method for sex estimation based on femoral cross-sectional geometry measurements and its validation using recent and ancient populations

Estimating sex is a fundamental task in biological and forensic anthropology. This study aimed to develop new methods for sex estimation based on femoral cross-sectional geometry (CSG) variables and to test their applicability in recent and ancient assemblages. The sample was divided into a study group (living individuals, N = 124) for creating sex prediction equations and two test groups: living individuals (N = 31) and prehistoric individuals (N = 34). The prehistoric sample was divided into three subgroups according to subsistence strategy (hunter-gatherers, early farmers that also hunted, and farmers and herders). Femoral CSG variables (size, strength, and shape) were measured from CT images using dedicated software. Discriminant functions for sex estimation were calculated for various bone completeness scenarios and validated using the test groups. Size and strength parameters were sexually dimorphic, while shape was not. Discriminant functions for sex estimation produced success rates in the living sample between 83.9 and 93.5%; the distal shaft yielded the highest results. Success rates were lower among the prehistoric test sample, with better results (83.3%) for the mid-Holocene population (farmers and herders) than for earlier groups (e.g., hunter-gatherers; < 60%). These results were compared with those obtained using other methods for sex estimation based on various skeletal elements. This study provides new, reliable, and simple methods with high success rates for sex estimation based on femoral CSG variables obtained automatically from CT images. Discriminant functions were created for various conditions of femoral completeness. However, these functions should be used carefully in past populations from different settings.

Variation in ontogenetic trajectories of limb dimensions in humans is attributable to both climatic effects and neutral evolution

Previous studies showed that there is variation in ontogenetic trajectories of human limb dimensions and proportions. However, little is known about the evolutionary significance of this variation. This study used a global sample of modern human immature long bone measurements and a multivariate linear mixed-effects model to study 1) whether the variation in ontogenetic trajectories of limb dimensions is consistent with ecogeographic predictions and 2) the effects of different evolutionary forces on the variation in ontogenetic trajectories. We found that genetic relatedness arising from neutral (nonselective) evolution, allometric variation associated with the change in size, and directional effects from climate all contributed to the variation in ontogenetic trajectories of all major long bone dimensions in modern humans. After accounting for the effects of neutral evolution and holding other effects considered in the current study constant, extreme temperatures have weak, positive associations with diaphyseal length and breadth measurements, while mean temperature shows negative associations with diaphyseal dimensions. The association with extreme temperatures fits the expectations of ecogeographic rules, while the association with mean temperature may explain the observed among-group variation in intralimb indices. The association with climate is present throughout ontogeny, suggesting an explanation of adaptation by natural selection as the most likely cause. On the other hand, genetic relatedness among groups, as structured by neutral evolutionary factors, is an important consideration when interpreting skeletal morphology, even for nonadult individuals.

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.

The utility of dried blood spot measurement of bone turnover markers in biological anthropology

OBJECTIVES

Bone is a dynamic organ under continual turnover influenced by life history stage, energy dynamics, diet, climate, and disease. Bone turnover data have enormous potential in biological anthropology for testing evolutionary and biocultural hypotheses, yet few studies have integrated these biomarkers. In the present article we systematically review the current availability, future viability, and applicability of measuring bone turnover markers (BTMs) in dried blood spot (DBS) samples obtained from finger prick whole blood.

METHODS

Our review considers clinical and public health relevance, biomarker stability in DBS, assay availability, and cost. We consider biomarkers of bone formation such as osteocalcin (bone matrix protein), PINP (N-terminal propeptide of type I collagen), and alkaline phosphatase (osteoblast enzyme), as well as biomarkers of bone resorption such as CTX (marker of collagen breakdown) and TRACP5b (tartrate-resistant acid phosphatase 5b; osteoclast enzyme).

RESULTS

Two BTMs have been validated for DBS: osteocalcin (formation) and TRACP5b (resorption). Prime candidates for future development are CTX and PINP, the formation and resorption markers used for clinical monitoring of response to osteoporosis treatment.

CONCLUSION

BTMs are a field-friendly technique for longitudinal monitoring of skeletal biology during growth, reproduction and aging, combining minimized risk to study participants with maximized ease of sample storage and transport. This combination allows new insights into the effects of energy availability, disease, and physical activity level on bone, and questions about bone gain and loss across life history and in response to environmental factors; these issues are important in human biology, paleoanthropology, bioarchaeology, and forensic anthropology.

Two Late Pleistocene human femora from Trinil, Indonesia: Implications for body size and behavior in Southeast Asia

Late Pleistocene hominin postcranial specimens from Southeast Asia are relatively rare. Here we describe and place into temporal and geographic context two partial femora from the site of Trinil, Indonesia, which are dated stratigraphically and via Uranium-series direct dating to ca. 37-32 ka. The specimens, designated Trinil 9 and 10, include most of the diaphysis, with Trinil 9 being much better preserved. Microcomputed tomography is used to determine cross-sectional diaphyseal properties, with an emphasis on midshaft anteroposterior to mediolateral bending rigidity (I_x/I_y), which has been shown to relate to both body shape and activity level in modern humans. The body mass of Trinil 9 is estimated from cortical area and reconstructed length using new equations based on a Pleistocene reference sample. Comparisons are carried out with a large sample of Pleistocene and Holocene East Asian, African, and European/West Asian femora. Our results show that Trinil 9 has a high I_x/I_y ratio, most consistent with a relatively narrow-bodied male from a mobile hunting-gathering population. It has an estimated body mass of 55.4 kg and a stature of 156 cm, which are small relative to Late Pleistocene males worldwide, but larger than the penecontemporaneous Deep Skull femur from Niah Cave, Malaysia, which is very likely female. This suggests the presence of small-bodied active hunter-gatherers in Southeast Asia during the later Late Pleistocene. Trinil 9 also contrasts strongly in morphology with earlier partial femora from Trinil dating to the late Early-early Middle Pleistocene (Femora II-V), and to a lesser extent with the well-known complete Femur I, most likely dating to the terminal Middle-early Late Pleistocene. Temporal changes in morphology among femoral specimens from Trinil parallel those observed in Homo throughout the Old World during the Pleistocene and document these differences within a single site.

Nutrition and Health in Human Evolution-Past to Present

Anyone who wants to understand the biological nature of humans and their special characteristics must look far back into evolutionary history. Today's way of life is drastically different from that of our ancestors. For almost 99% of human history, gathering and hunting have been the basis of nutrition. It was not until about 12,000 years ago that humans began domesticating plants and animals. Bioarchaeologically and biochemically, this can be traced back to our earliest roots. Modern living conditions and the quality of human life are better today than ever before. However, neither physically nor psychosocially have we made this adjustment and we are paying a high health price for it. The studies presented allow us to reconstruct food supply, lifestyles, and dietary habits: from the earliest primates, through hunter-gatherers of the Paleolithic, farming communities since the beginning of the Anthropocene, to the Industrial Age and the present. The comprehensive data pool allows extraction of all findings of medical relevance. Our recent lifestyle and diet are essentially determined by our culture rather than by our millions of years of ancestry. Culture is permanently in a dominant position compared to natural evolution. Thereby culture does not form a contrast to nature but represents its result. There is no doubt that we are biologically adapted to culture, but it is questionable how much culture humans can cope with.

Ancient mitochondrial diversity reveals population homogeneity in Neolithic Greece and identifies population dynamics along the Danubian expansion axis

The aim of the study is to investigate mitochondrial diversity in Neolithic Greece and its relation to hunter-gatherers and farmers who populated the Danubian Neolithic expansion axis. We sequenced 42 mitochondrial palaeogenomes from Greece and analysed them together with European set of 328 mtDNA sequences dating from the Early to the Final Neolithic and 319 modern sequences. To test for population continuity through time in Greece, we use an original structured population continuity test that simulates DNA from different periods by explicitly considering the spatial and temporal dynamics of populations. We explore specific scenarios of the mode and tempo of the European Neolithic expansion along the Danubian axis applying spatially explicit simulations coupled with Approximate Bayesian Computation. We observe a striking genetic homogeneity for the maternal line throughout the Neolithic in Greece whereas population continuity is rejected between the Neolithic and present-day Greeks. Along the Danubian expansion axis, our best-fitting scenario supports a substantial decrease in mobility and an increasing local hunter-gatherer contribution to the gene-pool of farmers following the initial rapid Neolithic expansion. Οur original simulation approach models key demographic parameters rather than inferring them from fragmentary data leading to a better understanding of this important process in European prehistory.

Variability and the form-function framework in evolutionary biomechanics and human locomotion

The form-function conceptual framework, which assumes a strong relationship between the structure of a particular trait and its function, has been crucial for understanding morphological variation and locomotion among extant and fossil species across many disciplines. In biological anthropology, it is the lens through which many important questions and hypotheses have been tackled with respect to relationships between morphology and locomotor kinematics, energetics and performance. However, it is becoming increasingly evident that the morphologies of fossil hominins, apes and humans can confer considerable locomotor diversity and flexibility, and can do so with a range of kinematics depending on soft tissue plasticity and environmental and cultural factors. This complexity is not built into traditional biomechanical or mathematical models of relationships between structure and kinematics or energetics, limiting our interpretation of what bone structure is telling us about behaviour in the past. The nine papers presented in this Special Collection together address some of the challenges that variation in the relationship between form and function pose in evolutionary biomechanics, to better characterise the complexity linking structure and function and to provide tools through which we may begin to incorporate some of this complexity into our functional interpretations.

Effects of reduced mobility on trabecular bone density in captive big cats

Bone responds to elevated mechanical loading by increasing in mass and density. Therefore, wild animals should exhibit greater skeletal mass and density than captive conspecifics. This expectation is pertinent to testing bone functional adaptation theories and to comparative studies, which commonly use skeletal remains that combine zoo and wild-caught specimens. Conservationists are also interested in the effects of captivity on bone morphology as it may influence rewilding success. We compared trabecular bone volume fraction (BVF) between wild and captive mountain lions, cheetahs, leopards and jaguars. We found significantly greater BVF in wild than in captive felids. Effects of captivity were more marked in the humerus than in the femur. A ratio of humeral/femoral BVF was also lower in captive animals and showed a positive relationship to home range size in wild animals. Results are consistent with greater forelimb than hindlimb loading during terrestrial travel, and possibly reduced loading of the forelimb associated with lack of predatory behaviour in captive animals. Thus, captivity among felids has general effects on BVF in the postcranial skeleton and location-specific effects related to limb use. Caution should be exercised when identifying skeletal specimens for use in comparative studies and when rearing animals for conservation purposes.

How the evolution of air breathing shaped hippocampal function

To make maps from airborne odours requires dynamic respiratory patterns. I propose that this constraint explains the modulation of memory by nasal respiration in mammals, including murine rodents (e.g. laboratory mouse, laboratory rat) and humans. My prior theories of limbic system evolution offer a framework to understand why this occurs. The answer begins with the evolution of nasal respiration in Devonian lobe-finned fishes. This evolutionary innovation led to adaptive radiations in chemosensory systems, including the emergence of the vomeronasal system and a specialization of the main olfactory system for spatial orientation. As mammals continued to radiate into environments hostile to spatial olfaction (air, water), there was a loss of hippocampal structure and function in lineages that evolved sensory modalities adapted to these new environments. Hence the independent evolution of echolocation in bats and toothed whales was accompanied by a loss of hippocampal structure (whales) and an absence of hippocampal theta oscillations during navigation (bats). In conclusion, models of hippocampal function that are divorced from considerations of ecology and evolution fall short of explaining hippocampal diversity across mammals and even hippocampal function in humans. This article is part of the theme issue 'Systems neuroscience through the lens of evolutionary theory'.

Tibial cortical and trabecular variables together can pinpoint the timing of impact loading relative to menarche in premenopausal females

OBJECTIVES

Though relationships between limb bone structure and mechanical loading have provided fantastic opportunities for understanding the lives of prehistoric adults, the lives of children remain poorly understood. Our aim was to determine whether or not adult tibial skeletal variables retain information about childhood/adolescent loading, through assessing relationships between cortical and trabecular bone variables and the timing of impact loading relative to menarche in premenopausal adult females.

METHODS

Peripheral quantitative computed tomography was used to quantify geometric and densitometric variables from the proximal tibial diaphysis (66% location) and distal epiphysis (4% location) among 81 nulliparous young adult female controls and athletes aged 19-33 years grouped according to intensity of impact loading both pre- and post-menarche: (1) Low:Low (Controls); (2) High:Low; (3) High:High; (4) Moderate:Moderate; (5) Low:Moderate. ANCOVA was used to compare properties among the groups adjusted for age, stature, and body mass.

RESULTS

Significant increases in diaphyseal total cross-sectional area and strength-strain index were documented among groups with any pre-menarcheal impact loading relative to groups with none, regardless of post-menarcheal loading history (p < .01). In contrast, significantly elevated distal trabecular volumetric bone mineral density was only documented among groups with recent post-menarcheal loading relative to groups with none, regardless of pre-menarcheal impact loading history (p < .01).

CONCLUSIONS

The consideration of diaphyseal cortical bone geometric and epiphyseal trabecular bone densitometric variables together within the tibia can identify variation in pre-menarcheal and post-menarcheal impact loading histories among premenopausal adult females.

What is normal bone health? A bioarchaeological perspective on meaningful measures and interpretations of bone strength, loss, and aging

Bioarchaeological (the study of archeological human remains together with contextual and documentary evidence) offers a unique vantage point to examine variation in skeletal morphology related to influences such as activity, disease, and nutrition. The human skeleton is composed of a dynamic tissue that is forged by biocultural factors over the entire life course, providing a record of individual, and community history. Various aspects of adult bone health, particularly bone maintenance and loss and the associated skeletal disease osteoporosis, have been examined in numerous past populations. The anthropological study of bone loss has traditionally focused on the signature of postmenopausal aging, costs of reproduction, and fragility in females. The a priori expectation of normative sex-related bone loss/fragility in bioanthropological studies illustrates the wider gender-ideological bias that continues in research design and data analysis in the field. Contextualized data on bone maintenance and aging in the archeological record show that patterns of bone loss do not constitute predictable consequences of aging or biological sex. Instead, the critical examination of bioarchaeological data highlights the complex and changing processes that craft the human body over the life course, and calls for us to question the ideal or "normal" range of bone quantity and quality in the human skeleton, and to critically reflect on what measures are actually biologically and/or socially meaningful.

Approaches to osteoporosis in paleopathology: How did methodology shape bone loss research?

OBJECTIVE

This paper will review how different methods employed to study bone loss in the past were used to explore different questions and aspects of bone loss, how methodology has changed over time, and how these different approaches have informed our understanding of bone loss in the past.

MATERIALS AND METHODS

A review and discussion is conducted on research protocols and results of 84 paleopathology publications on bone loss in archaeological skeletal collections published between 1969 and 2021.

CONCLUSIONS

The variety in research protocols confounds accurate meta-analysis of previously published research; however, more recent publications incorporate a combination of bone mass and bone quality based methods. Biased sample selection has resulted in a predominance of European and Medieval publications, limiting more general observations on bone loss in the past. Collection of dietary or paleopathological covariables is underemployed in the effort to interpret bone loss patterns.

SIGNIFICANCE

Paleopathology publications have demonstrated differences in bone loss between distinct archaeological populations, between sex and age groups, and have suggested factors underlying observed differences. However, a lack of a gold standard has encouraged the use of a wide range of methods. Understanding how this array of methods effects results is crucial in contextualizing our knowledge of bone loss in the past.

LIMITATIONS

The development of a research protocol is also influenced by available expertise, available equipment, restrictions imposed by the curator, and site-specific taphonomic aspects. These factors will likely continue to cause (minor) biases even if a best practice can be established.

SUGGESTIONS FOR FUTURE RESEARCH

Greater effort to develop uniform terminology and operational definitions of osteoporosis in skeletal remains, as well as the expansion of time scale and geographical areas studied. The Next-Generation Sequencing revolution has also opened up the possibility of ancient DNA analyses to study genetic predisposition to bone loss in the past.

Adapting in the Arctic: Habitual activity and landscape interaction in Late Holocene hunter-gatherers from Alaska

OBJECTIVES

This study compares lower limb diaphyseal robusticity between Native Alaskan hunter-gatherers to reconstruct patterns of mobility and engagement with terrain.

MATERIALS AND METHODS

Ancestral remains included in this study date between 600 and 1800 C.E. and were divided into three regions: Coastal Bay, Far North Coastal, and Inland/Riverine. Cross-sectional properties were determined at femoral and tibial midshafts and standardized by powers of body mass and bone length.

RESULTS

Consistently elaevated areas and second moments of area were found in ancestral remains from the Far North Coastal, while the Coastal Bay remains had reduced diaphyseal robusticity. Individuals from the Inland/Riverine region were intermediate in robusticity for male femora, but similar to the Coastal Bay group for females. Sexual dimorphism was greatest in the Inland/Riverine ancestral remains and comparable between Coastal Bay and Far North Coastal regions.

CONCLUSIONS

Ancestral remains from the Far North Coastal region have the greatest diaphyseal robusticity in response to intensive hunting and travel over rugged terrain. Reduced sexual dimorphism in the Far North Coastal region suggest female participation in hunting activities. Intermediate diaphyseal robusticity among Inland/Riverine males and increased sexual dimorphism reflects diverse patterns of mobility in relation to the hunting cycle between males and females. Reduced diaphyseal robusticity and sexual dimorphism among the Coastal Bay group is associated with sedentary villages established around net fishing in regions with low relief. Such findings argue against technocentric views of sedentism in hunter-gatherer lifeways and generally reflect diverse adaptive strategies and interaction with local terrain among Indigenous Late Holocene hunter-gatherers of Alaska.

Sex differences in diet and life conditions in a rural Medieval Islamic population from Spain (La Torrecilla, Granada): An isotopic and osteological approach to gender differentiation in al-Andalus

OBJECTIVES

Gender differentiation can influence the diet, physical activity, and health of human populations. Multifaceted approaches are therefore necessary when exploring the biological consequences of gender-related social norms in the past. Here, we explore the links between diet, physiological stress, physical activity, and gender differentiation in the Medieval Islamic population of La Torrecilla (Granada, Spain, 13th-15th century AD), by analyzing stable isotope patterns, stature, and long bone diaphyseal measurements.

MATERIALS AND METHODS

The sample includes 96 individuals (48 females, 48 males) classified as young and middle adults (20-34 and 35-50 years of age respectively). Diet was reconstructed through the analysis of δ¹³ C and δ¹⁵ N. Stature, humeral and femoral diaphyseal shape and product of diaphyseal diameters served as proxies of physiological stress and physical activity.

RESULTS

Isotopic ratios suggest a substantial dietary contribution of C₄ plants (e.g., sorghum, millet), a variable access to animal proteins, and no differences between the sexes. Sexual dimorphism in stature derives from a markedly low female stature. Long bone diaphyseal properties suggest that men performed various physically stressful activities, whereas women were involved in less physically demanding activities (possibly related to household work).

DISCUSSION

Gender differentiation in La Torrecilla was expressed by a possibly differential parental investment in male versus female offspring and by culturally sanctioned gender differences in the performance of physical tasks. Diet was qualitatively homogenous between the sexes, although we cannot rule out quantitative differences. Our results shed new light on the effects of gender-related social norms on human development and lifestyle.

Early ontogeny of humeral trabecular bone in Neandertals and recent modern humans

Trabecular bone ontogeny is well known in modern humans and unknown in Neandertals. Yet the bone developmental pattern is useful for interpreting fossils from evolutionary and functional perspectives. Interestingly, microstructure in early ontogeny is supposedly not influenced by high and specific mechanical loading related to the lifestyle of a human group and consequently does not directly depend on the activities of hunter-gatherers. Here, we specifically explored the early growth trajectories of the trabecular bone structure of the humerus and emphasized in particular how bone fraction (bone volume/total volume [BV/TV]) was built up in Neandertals, given the specific modern human bone loss after birth and the use of BV/TV in functional studies. Six Neandertals and 26 recent modern humans ranging from perinates to adolescents were included in this study. Six trabecular parameters were measured within a cubic region of interest extracted from the proximal metaphysis of the humerus. We found that the microstructural changes in Neandertals during early ontogeny (<1 year) fit with modern human growth trajectories for each parameter. The specific bone loss occurring immediately after birth in modern humans also occurred in Neandertals (but not in chimpanzees). However, the early childhood fossil Ferrassie 6 presented unexpectedly high BV/TV, whereas the high BV/TV in the Crouzade I adolescent was predictable. These results suggest that Neandertals and modern humans shared predetermined early growth trajectories and developmental mechanisms. We assume that the close relationship between skeletal characteristics in early ontogeny and adults in modern humans also existed in Neandertals. However, it was difficult to ensure that the high BV/TV in Neandertal early childhood, represented by only one individual, was at the origin of the high BV/TV observed in adults. Consequently, our study does not challenge the mechanical hypothesis that explains the trabecular gracilization of the humerus during the Holocene.

Pathways linking activity, adiposity, and inflammation to bone mineral density in women and men from NHANES 2007 to 2010

OBJECTIVES

Age, sedentary activity, central adiposity, and inflammation have all been independently associated with bone mineral density (BMD). We assessed how the effects of sedentary activity and central adiposity on BMD of the lumbar spine and femoral neck change across early to late adulthood and whether these relationships are mediated by inflammation.

METHODS

We analyzed data from 7135 women and men 20 years of age and older from NHANES 2007 to 2010. Anthropometrics, sedentary activity (min/day), serum CRP (mg/dl), and BMD (gm/cm² measured by DXA scans) at the femoral neck and lumbar spine. Data were compared by age and sex groups and through causal mediation analysis.

RESULTS

The effect of waist circumference on BMD was significantly mediated by serum CRP at both skeletal sites in men and at the femoral neck in women. Sedentary activity did not have a direct relationship to BMD but was mediated by waist circumference in men. Least square means differed significantly by sex and age groups with a general age-related decline in BMD at both skeletal sites.

CONCLUSIONS

We found that central adiposity, independent of overall body size and composition as measured through BMI, has an inverse relationship with BMD that is mediated by serum CRP. In addition, the negative impact of increased sedentism acted through changes in central adiposity (waist circumference) but only in men. Although low bone density and osteoporosis are often considered degenerative diseases that primarily impact postmenopausal women, our findings show that sedentary activity and central adiposity impact bone density beginning in early adulthood in both women and men.

Age-related site-specific modifications in diaphyseal structural properties of the human fibula: Furrows and cross-sectional geometry

OBJECTIVES

Fibular structure is related to locomotor behavior, which allows an exploration of mobility in past human populations with diaphyseal cross-sectional geometry (CSG). However, bone structure depends on age-related changes. Nonmechanical alterations can affect biomechanical investigations. In this study, we examined how the cortical area and the variables used as functional markers in the fibular diaphysis (i.e., CSG and furrows) change with aging. We predict classic and specific modifications, and we discuss functional interpretations based on bone structure.

MATERIALS AND METHODS

The sample consisted of 124 individuals of known age in whom the fibular furrow depths were measured with calipers. Microcomputed tomography (micro-CT) scanning of 38 individuals provided CSG (e.g., cortical area, shape index, and robusticity) and fibular furrow indices. CSG was studied at five cross sections taken along the diaphysis. Linear regression analyses and age group comparisons were conducted.

RESULTS

The cross-sectional shape summary by fibular furrows and shape index and the total area did not change with aging; in contrast, the cortical area and the robusticity (Z_p-std) decreased with age.

DISCUSSION

The decrease in robusticity (Z_p-std) with aging is due to the maintenance of total area, which is related to the specific mechanical environment of the fibula, and to the loss of cortical bone and not to the decrease in mechanical stress. This finding is consistent with the lower bone modeling capacity in aged individuals, which also explains the lack of significant changes in the diaphyseal shape. Thus, fibular structure in older individuals is due to a combination of early bone adaptations to stress and aging effects.

Assessing patterns of variation in BV/TV in the calcaneus and C2 vertebra of Gorilla gorilla, Pan troglodytes, and populations of Homo sapiens from the Pleistocene and Holocene that differ in physical activity levels

OBJECTIVES

Because trabecular bone volume fraction (BV/TV) is influenced by variations in physical activity recent declines in BV/TV in humans are often attributed to modern sedentary lifestyles. This study tests the hypothesis that presumed variations in mechanical loading between groups can predict the observed BV/TV patterns in humans, chimpanzees and gorillas in two bones: the calcaneus which experiences high and well characterized impact forces, and the C2 vertebrae which experiences reduced locomotor forces.

MATERIALS AND METHODS

BV/TV and other structural variables were quantified from high-resolution microCT scans in gorillas, chimpanzees, and four Homo sapiens populations: Pleistocene, semi-sedentary Natufians; Holocene hunter-gatherers from Point Hope, Alaska; Holocene nomadic pastoralists from medieval Europe; and modern, sedentary Americans.

RESULTS

In the calcaneal tuberosity, Natufian BV/TV was 36, 46, and 46% greater than Alaskans (p = .02), Europeans (p = .005) and modern Americans (p = .002), respectively, but not significantly different from apes. BV/TV was not significantly different between modern Americans and Alaskans or Europeans. In the C2, Natufian BV/TV was 53 and 25% greater than in the Alaskan (p = .0001) and European (p = .048) populations.

DISCUSSION

These results suggest that phenomena other than or in addition to variations in physical activity are needed to explain BV/TV patterns observed in H. sapiens, and point to a systemic decline in H. sapiens BV/TV after the Pleistocene.

Combinations of trabecular and cortical bone properties distinguish various loading modalities between athletes and controls

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.

The upper limb skeleton and behavioral lateralization of modern humans from Zhaoguo Cave, southwestern China

OBJECTIVES

Aims of the study are to initially describe and comparatively evaluate the morphology of the new Zhaoguo M1 upper limb remains, and contextualize upper limb functional adaptations among those of other worldwide Upper Paleolithic (UP) humans to make inferences about subsistence-related activity patterns in southwestern China at the Pleistocene-Holocene boundary.

MATERIALS AND METHODS

The preserved Zhaoguo M1 skeletal remains include paired humeri, ulnae, and radii, among others. These specimens were scanned using micro-computed tomography to evaluate internal structural properties, while external osteometric dimensions of the Zhaoguo M1 upper limb elements also were acquired. Both sets of measurements were compared to published data on Neandertals, and Middle and Upper Paleolithic modern humans.

RESULTS

The upper limb elements of Zhaoguo M1 display a suite of characteristics that generally resemble those of other contemporary Late UP (LUP) modern humans, while robusticity indices generally fall within the upper range of LUP variation. The Zhaoguo M1 upper limb elements display fewer traits resembling those of late archaic humans. The Zhaoguo M1 individual exhibits diaphyseal asymmetry in several upper limb elements suggesting left hand dominance. When evaluating the full range of magnitudes of humeral bilateral asymmetry in the comparative sample, Zhaoguo M1 falls at the lower end overall, but yet is relatively higher than contemporary LUP modern humans specifically from East Eurasia.

DISCUSSION

The Zhaoguo M1 individual suggests typical LUP modern human upper limb morphology persisted in southwest China until the end of the last glacial period. Upper limb bone asymmetry of Zhaoguo M1 also indicates that behavioral activities attributed to a hunter-gatherer tradition apparently extended through the Pleistocene-Holocene transition in this region.

Skeletal ageing in Virunga mountain gorillas

Bone loss and heightened fracture risk are common conditions associated with ageing in modern human populations and have been attributed to both hormonal and other metabolic and behavioural changes. To what extent these age-related trends are specific to modern humans or generally characteristic of natural populations of other taxa is not clear. In this study, we use computed tomography to examine age changes in long bone and vertebral structural properties of 34 wild-adult Virunga mountain gorillas (Gorilla beringei beringei) whose skeletons were recovered from natural accumulations. Chronological ages were known or estimated from sample-specific dental wear formulae and ranged between 11 and 43 years. Gorillas show some of the same characteristics of skeletal ageing as modern humans, including endosteal and some periosteal expansion. However, unlike in humans, there is no decline in cortical or trabecular bone density, or in combined geometric-density measures of strength, nor do females show accelerated bone loss later in life. We attribute these differences to the lack of an extended post-reproductive period in gorillas, which provides protection against bone resorption. Increases in age-related fractures (osteoporosis) in modern humans may be a combined effect of an extended lifespan and lower activity levels earlier in life. This article is part of the theme issue 'Evolution of the primate ageing process'.

Morphological evidence for early dog domestication in the European Pleistocene: New evidence from a randomization approach to group differences

The antiquity of the wolf/dog domestication has been recently pushed back in time from the Late Upper Paleolithic (~14,000 years ago) to the Early Upper Paleolithic (EUP; ~36,000 years ago). Some authors questioned this early dog domestication claiming that the putative (EUP) Paleolithic dogs fall within the morphological range of recent wolves. In this study, we reanalyzed a data set of large canid skulls using unbalanced- and balanced-randomized discriminant analyses to assess whether the putative Paleolithic dogs are morphologically unique or whether they represent a subsample of the wolf morpho-population. We evaluated morphological differences between 96 specimens of the 4 a priori reference groups (8 putative Paleolithic dogs, 41 recent northern dogs, 7 Pleistocene wolves, and 40 recent northern wolves) using discriminant analysis based on 5 ln-transformed raw and allometrically size-adjusted cranial measurements. Putative Paleolithic dogs are classified with high accuracies (87.5 and 100.0%, cross-validated) and randomization experiment suggests that these classification rates cannot be exclusively explained by the small and uneven sample sizes of reference groups. It indicates that putative Upper Paleolithic dogs may represent a discrete canid group with morphological signs of domestication (a relatively shorter skull and wider palate and braincase) that distinguish them from sympatric Pleistocene wolves. The present results add evidence to the view that these specimens could represent incipient Paleolithic dogs that were involved in daily activities of European Upper Paleolithic forager groups.

Gendered division of labor in a Celtic community? A comparison of sex differences in entheseal changes and long bone shape and robusticity in the pre-Roman population of Verona (Italy, third-first century BC)

OBJECTIVES

The presence of a gendered subdivision of labor has been bioarchaeologically investigated in various prehistoric and historical contexts. Little is known, however, about the type of differences in daily activities characterizing men and women among the Celtic communities of Italy. The focus of the present study is the analysis of differences in patterns of entheseal changes (ECs) and long bone shape and robusticity between sexes among the Cenomani Gauls of Seminario Vescovile (SV-Verona, Italy, third-first century BC).

MATERIALS AND METHODS

The sample includes 56 adult individuals (22 females and 34 males). Presence of ECs on nine bilateral postcranial attachment sites, and values of humeral and femoral shape and robusticity indices based on external measurements were compared between sexes by means of generalized linear models and Mann-Whitney tests.

RESULTS

Results show a lack of difference between sexes in long bone shape and robusticity, and a higher incidence of upper and, especially, lower limb ECs in males.

DISCUSSION

These results suggest the presence of sex-specific activities at SV mostly related to farming and differently influencing the considered variables. Also, this study suggests the relevance of a series of nonbiomechanical factors (developmental, hormonal, genetic, and methodological) when attempting biocultural reconstructions from osteoarchaeological samples.

Muscle force interacts with stature to influence functionally related polar second moments of area in the lower limb among adult women

Objectives

We sought to determine the relationships between muscle size, function, and polar second moments of area (J) at the midshaft femur, proximal tibia, and midshaft tibia.

Materials and Methods

We used peripheral quantitative computed tomography to quantify right femoral and tibial J and soft tissue cross‐sectional areas, and force plate mechanography to quantify peak power output and maximum force of the right limb, among athletic women and control subjects.

Results

Lower limb bone J exhibited strong relationships with estimated force but not power between both groups. Among controls, the strongest relationships between force and J were found at the midshaft femur. Among athletes, these relationships shifted to the tibia, regardless of body size, likely reflecting functional strain related to the major knee extensors and ankle plantarflexors. Together, muscle force and stature explained as much as 82 and 48% of the variance in lower limb bone J among controls and athletes, respectively.

Discussion

Results highlight the importance of considering relevant muscle function variables (e.g., force and lever arm lengths) when interpreting behavioral signatures from skeletal remains. Future work to improve the estimation of muscle force from skeletal remains, and incorporate it with lever arm length into analyses, is warranted. Results also suggest that, in doing so, functional relationships between a given section location and musculature should be considered.

Are entheseal changes and cross-sectional properties associated with the shape of the upper limb?

OBJECTIVES

Reconstruction of the activity of past human populations can be carried out using various skeletal markers; however, the relationship between these methods is not fully understood. Therefore, the main aim of this article is to analyze the relationship between entheseal changes, cross-sectional properties, and variability in the shape of the upper limb.

MATERIALS AND METHODS

The analyzed material consisted of CT images of 71 right scapulae, humeri, and ulnae belonging to the same individuals from a mediaeval population located in Poland. For each series of bones for the same individual, skeletal markers such as: cross-sectional properties, entheses and shape variation were assessed. Next, correlations between these three skeletal indicators were calculated.

RESULTS

In general, the models showed that only sex influences entheses. Multivariate regression revealed significant correlation only between ulnar auricular surface shape and two types of mean score for entheses.

DISCUSSION

The findings are inconsistent and stand in contradiction to other research; therefore, we suggest that an assessment of individual activity should be carried out, using as many post-cranial elements as possible and a variety of methods. This approach will ensure more accurate reconstruction of the activity levels and patterns of archeological groups.

Sex differences in the patterning of age-related bone loss in the human hallucal metatarsal in rural and urban populations

OBJECTIVES

Age-degenerative features of the metatarsals are poorly known despite the importance of metatarsal bone properties for investigating mobility patterns. We assessed the role of habitual activity in shaping the patterning and magnitude of sexual dimorphism in age-related bone loss in the hallucal metatarsal.

MATERIALS AND METHODS

Cross-sections were extracted at midshaft from micro-computed tomography scan models of individuals from medieval rural (Abingdon Vineyard) and early industrial urban (Spitalfields) settings (n = 71). A suite of cross-sectional geometry dimensions and biomechanical properties were compared between populations.

RESULTS

The rural group display generally stronger and larger metatarsals that show a greater capacity to resist torsion and that have comparatively greater bending strength along the medio-lateral plane. Men in both groups show greater values of cortical area than women, but only in the urban group do men show lower magnitudes of age-related decline compared to females. Women in rural and urban populations show different patterns of age-related decline in bone mass, particularly old women in the urban group show a marked decline in cortical area that is absent for women in the rural group.

DISCUSSION

Lifetime exposure to hard, physical activity in an agricultural setting has contributed to the attainment of greater bone mass and stronger bones in young adults. Furthermore, over the life-course, less of this greater amount of bone is lost, such that sustained activity levels may have acted to buffer against age-related decline, and this is most pronounced for women, who are expected to experience greater bone loss later in life than men.

Evolutionary Perspectives on the Developing Skeleton and Implications for Lifelong Health

Osteoporosis is a significant cause of morbidity and mortality in contemporary populations. This common disease of aging results from a state of bone fragility that occurs with low bone mass and loss of bone quality. Osteoporosis is thought to have origins in childhood. During growth and development, there are rapid gains in bone dimensions, mass, and strength. Peak bone mass is attained in young adulthood, well after the cessation of linear growth, and is a major determinant of osteoporosis later in life. Here we discuss the evolutionary implications of osteoporosis as a disease with developmental origins that is shaped by the interaction among genes, behavior, health status, and the environment during the attainment of peak bone mass. Studies of contemporary populations show that growth, body composition, sexual maturation, physical activity, nutritional status, and dietary intake are determinants of childhood bone accretion, and provide context for interpreting bone strength and osteoporosis in skeletal populations. Studies of skeletal populations demonstrate the role of subsistence strategies, social context, and occupation in the development of skeletal strength. Comparisons of contemporary living populations and archeological skeletal populations suggest declines in bone density and strength that have been occurring since the Pleistocene. Aspects of western lifestyles carry implications for optimal peak bone mass attainment and lifelong skeletal health, from increased longevity to circumstances during development such as obesity and sedentism. In light of these considerations, osteoporosis is a disease of contemporary human evolution and evolutionary perspectives provide a key lens for interpreting the changing global patterns of osteoporosis in human health.

Life History Transitions at the Origins of Agriculture: A Model for Understanding How Niche Construction Impacts Human Growth, Demography and Health

Over recent millennia, human populations have regularly reconstructed their subsistence niches, changing both how they obtain food and the conditions in which they live. For example, over the last 12,000 years the vast majority of human populations shifted from foraging to practicing different forms of agriculture. The shift to farming is widely understood to have impacted several aspects of human demography and biology, including mortality risk, population growth, adult body size, and physical markers of health. However, these trends have not been integrated within an over-arching conceptual framework, and there is poor understanding of why populations tended to increase in population size during periods when markers of health deteriorated. Here, we offer a novel conceptual approach based on evolutionary life history theory. This theory assumes that energy availability is finite and must be allocated in competition between the functions of maintenance, growth, reproduction, and defence. In any given environment, and at any given stage during the life-course, natural selection favours energy allocation strategies that maximise fitness. We argue that the origins of agriculture involved profound transformations in human life history strategies, impacting both the availability of energy and the way that it was allocated between life history functions in the body. Although overall energy supply increased, the diet composition changed, while sedentary populations were challenged by new infectious burdens. We propose that this composite new ecological niche favoured increased energy allocation to defence (immune function) and reproduction, thus reducing the allocation to growth and maintenance. We review evidence in support of this hypothesis and highlight how further work could address both heterogeneity and specific aspects of the origins of agriculture in more detail. Our approach can be applied to many other transformations of the human subsistence niche, and can shed new light on the way that health, height, life expectancy, and fertility patterns are changing in association with globalization and nutrition transition.

THE EXPOSOME IN HUMAN EVOLUTION: FROM DUST TO DIESEL

Global exposures to air pollution and cigarette smoke are novel in human evolutionary history and are associated with about 16 million premature deaths per year. We investigate the history of the human exposome for relationships between novel environmental toxins and genetic changes during human evolution in six phases. Phase I: With increased walking on savannas, early human ancestors inhaled crustal dust, fecal aerosols, and spores; carrion scavenging introduced new infectious pathogens. Phase II: Domestic fire exposed early Homo to novel toxins from smoke and cooking. Phases III and IV: Neolithic to preindustrial Homo sapiens incurred infectious pathogens from domestic animals and dense communities with limited sanitation. Phase V: Industrialization introduced novel toxins from fossil fuels, industrial chemicals, and tobacco at the same time infectious pathogens were diminishing. Thereby, pathogen-driven causes of mortality were replaced by chronic diseases driven by sterile inflammogens, exogenous and endogenous. Phase VI: Considers future health during global warming with increased air pollution and infections. We hypothesize that adaptation to some ancient toxins persists in genetic variations associated with inflammation and longevity.

Genetic contributions to variation in human stature in prehistoric Europe

Measurements of prehistoric human skeletal remains provide a record of changes in height and other anthropometric traits over time. Often, these changes are interpreted in terms of plastic developmental response to shifts in diet, climate, or other environmental factors. These changes can also be genetic in origin, but, until recently, it has been impossible to separate the effects of genetics and environment. Here, we use ancient DNA to directly estimate genetic changes in phenotypes and to identify changes driven not by genetics, but by environment. We show that changes over the past 35,000 y are largely predicted by genetics but also identify specific shifts that are more likely to be environmentally driven.

The relative contributions of genetics and environment to temporal and geographic variation in human height remain largely unknown. Ancient DNA has identified changes in genetic ancestry over time, but it is not clear whether those changes in ancestry are associated with changes in height. Here, we directly test whether changes over the past 38,000 y in European height predicted using DNA from 1,071 ancient individuals are consistent with changes observed in 1,159 skeletal remains from comparable populations. We show that the observed decrease in height between the Early Upper Paleolithic and the Mesolithic is qualitatively predicted by genetics. Similarly, both skeletal and genetic height remained constant between the Mesolithic and Neolithic and increased between the Neolithic and Bronze Age. Sitting height changes much less than standing height—consistent with genetic predictions—although genetics predicts a small post-Neolithic increase that is not observed in skeletal remains. Geographic variation in stature is also qualitatively consistent with genetic predictions, particularly with respect to latitude. Finally, we hypothesize that an observed decrease in genetic heel bone mineral density in the Neolithic reflects adaptation to the decreased mobility indicated by decreased femoral bending strength. This study provides a model for interpreting phenotypic changes predicted from ancient DNA and demonstrates how they can be combined with phenotypic measurements to understand the relative contribution of genetic and developmentally plastic responses to environmental change.