Mobility and subsistence economy: A diachronic comparison between two groups settled in the same geographical area (Liguria, Italy)

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.

Sex differences in workload in medieval Poland: Patterns of asymmetry and biomechanical adaptation in the upper limb at Giecz

OBJECTIVES

This study characterizes sexual dimorphism in skeletal markers of upper limb mechanical loading due to lateralization as evidence of division of labor in medieval Giecz, Poland.

METHODS

Twenty-six dimensions for paired humeri, clavicles, and radii representing adult males (n = 89) and females (n = 53) were collected from a skeletal sample from the cemetery site Gz4. Percent directional asymmetry (DA) and absolute asymmetry (AA) for each dimension were compared among bones, osteometric subcategories, and sex. Additionally, side bias and sex differences were assessed in degenerative joint disease (DJD) and entheseal changes (ECs).

RESULTS

Nearly all measurements revealed significant asymmetry favoring the right side. Asymmetry was most pronounced in midshaft dimensions with few sex differences. There were more correlations among dimensions within elements than between elements, mainly in the midshaft. No laterality in DJD frequencies was noted for either sex, but females demonstrated significantly lower odds of having DJD than males in most joints. Most ECs demonstrated a right-bias and association with DA with no sex-specific patterns except the biceps brachii insertion, where females were ~5 times more likely to be scored "right" than males.

DISCUSSION

The general lack of sex differences in asymmetry and ECs suggests similarly demanding workloads for females and males, with the exception of sex-specific functional loading differences in the forearm. Further, DJD data suggest males engaged in more intensive activities involving the upper limb. These results enhance understanding of workload in this important historical period and provide a comparison for asymmetry in past populations.

Entheseal changes and activity patterns in southern African hunter-gatherer/herders from the Holocene

OBJECTIVES

Activity patterns and lifeways in southern African hunter-gatherer/herders (sAHGH) during the Holocene were dynamic, with subsistence activities and mobility varying through space and time. In this study, spatial and temporal variations in entheseal changes (ECs) are assessed as physical activity markers in sAHGH from the Holocene.

METHODS

The Coimbra method was used to assess fibrocartilaginous ECs in the upper and lower limbs of 118 sAHGH from the Holocene. Descriptive statistics and generalized estimating equations were used to explore the association between ECs, sex, age, ecological biomes, and temporality.

RESULTS

A total of 118 individuals were sampled, comprising 67 males, and 42 females, mostly from the fynbos (59/118), forest (30/118) and succulent karoo biomes (16/118). ECs were identified in 94% of the sample. Interobserver scoring suggests our findings are likely to underrepresent the extent of EC score differences in sAHGH. Findings indicate a complex pattern of physical activity in sAHGH with differences attributable to regional ecology rather than age or sex. More prominent ECs were identified in individuals from the forest biome, relative to the fynbos and succulent karoo biomes. These were consistent with resource search and processing costs, and terrain differences in these ecozones. ECs were only detected temporally relative to the infiltration of pastoralism (at 2000 BP) when the data were stratified by ecological biome.

DISCUSSION

This study provides evidence that regional ecology plays a central role in driving activity patterns regardless of social or cultural organization. Ecological biomes provide a gradient along which the temporal impact of resource limitations on human biology, activity patterns and sociocultural behaviors can be studied.

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.

Contextualizing bilateral asymmetry and gender: A multivariate approach to femoral cross-sectional geometry at rural Medieval Pieve di Pava, Italy

OBJECTIVES

Our objective was to identify the relationship between biocultural factors of sex-gender and age and patterns of femoral cross-sectional geometry with historical evidence about labor and activity from an archeological skeletal sample excavated from the rural Medieval site Pieve di Pava.

MATERIALS AND METHODS

The study site, Pieve di Pava, was a rural parish cemetery in Tuscany with osteoarcheological remains from the 7th to 12th centuries. Cross-sectional geometric analysis of femora from 110 individuals dated to the 10th-12th centuries were used to examine trends in bone quantity, shape, and bending strength between age and sex groups, as well as in clusters identified through Hierarchical Cluster Analysis (HCA).

RESULTS

Overall, our study sample showed remarkable heterogeneity and our cluster analysis revealed a complex underlying structure, indicating that divisions of labor did not follow a strict gender binary in our sample. We found high levels of bilateral asymmetry in our sample in multiple cross-sectional areas for a significant proportion of the population. We found minimal differences between age groups or sex.

DISCUSSION

Our results suggest that males and females had varied experiences of labor and work during their lives that did not reflect the strict binary gender roles sometimes documented for medieval Europe. One important axis of difference is the direction and magnitude of bilateral asymmetry observed in our femur sample, which is associated with divergent trends in section moduli and bone area measures.

Variation in cross-sectional indicator of femoral robusticity in Homo sapiens and Neandertals

Variations in the cross-sectional properties of long bones are used to reconstruct the activity of human groups and differences in their respective habitual behaviors. Knowledge of what factors influence bone structure in Homo sapiens and Neandertals is still insufficient thus, this study investigated which biological and environmental variables influence variations in the femoral robusticity indicator of these two species. The sample consisted of 13 adult Neandertals from the Middle Paleolithic and 1959 adult individuals of H. sapiens ranging chronologically from the Upper Paleolithic to recent times. The femoral biomechanical properties were derived from the European data set, the subject literature, and new CT scans. The material was tested using a Mantel test and statistical models. In the models, the polar moment of area (J) was the dependent variable; sex, age, chronological period, type of lifestyle, percentage of the cortical area (%CA), the ratio of second moment areas of inertia about the X and Y axes (Ix/Iy), and maximum slope of the terrain were independent covariates. The Mantel tests revealed spatial autocorrelation of the femoral index in H. sapiens but not in Neandertals. A generalized additive mixed model showed that sex, %CA, Ix/Iy, chronological period, and terrain significantly influenced variation in the robusticity indicator of H. sapiens femora. A linear mixed model revealed that none of the analyzed variables correlated with the femoral robusticity indicator of Neandertals. We did not confirm that the gradual decline in the femoral robusticity indicator of H. sapiens from the Middle Paleolithic to recent times is related to the type of lifestyle; however, it may be associated with lower levels of mechanical loading during adolescence. The lack of correlation between the analysed variables and the indicator of femoral robusticity in Neandertals may suggest that they needed a different level of mechanical stimulus to produce a morphological response in the long bone than H. sapiens.

Mobility in Ancient Egypt from the shape and strength of the femurs

The aim of the study was to establish the degree of robustness and to infer the level of mobility of a group from ancient Thebes (Middle Egypt). Seventy-one left femurs of adult individuals from the 1st century AD from the tomb of Monthemhat (Luxor) were studied.

Metrical, non-metrical variables, shape and size indices of femur were considered. Stature, body mass and Body Mass Index were calculated. All variables showed higher values in males, the vertical diameter of the femoral head was the variable with the highest sexual dimorphism. Non-metric variables also indicated low robustness, with heterogeneous sex distribution. The robustness, pilastric and platymeric indices indicated that the values were close to those of gracile populations in both sexes. Subtrochanteric size and shape showed no sexual dimorphism. The robustness, size and shape in the middle of the diaphysis suggested a mobility related to a daily occupation without intense physical activity in the legs. The results indicate a profile of low robustness, relative sedentarism with apparent sexual division in daily activities.

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.

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.

Insights on patterns of developmental disturbances from the analysis of linear enamel hypoplasia in a Neolithic sample from Liguria (northwestern Italy)

OBJECTIVE

To assess developmental disturbances through the analysis of linear enamel hypoplasia (LEH) frequency and to infer environmental stress and life history within Neolithic communities from Liguria (Italy).

MATERIALS

43 unworn/minimally worn permanent anterior teeth of 13 individuals recovered from nearby caves and dated to c. 4800-4400 cal. BCE.

METHODS

LEH defects were identified with high-resolution macrophotos of dental replicas, age at LEH was calculated via perikymata counts. LEH defects matched between two or more teeth were considered as systemic disturbances. LEH frequency by age classes was analyzed via GLZ and Friedman ANOVA.

RESULTS

Number of matched defects per individual range between 2-12. The mean LEH per individual was highest in the 2.5-2.99 age category, with a significant increase relative to earlier growth stages, followed by a decline.

CONCLUSION

LEH may reflect life-history in the local ecology of Neolithic Liguria, where several individuals with osteoarticular tuberculosis have been recorded. Disease burden may have triggered developmental disturbances around the time of weaning. Age at first defect was negatively correlated with age at death and positively with the total number of defects, suggesting that early stress may have affected survivorship.

SIGNIFICANCE

The study contributes to the reconstruction of ecological pressures among Neolithic people of Liguria, and informs on environmental challenges during the Neolithic adaptive expansion.

LIMITATIONS

The visual examination of macrophotos is prone to observer error; mid-crown tends to display more visible LEH due to tooth architecture.

SUGGESTIONS FOR FURTHER RESEARCH

Apply different quantitative methods to examine severity and duration of disturbances.

Environmental correlates of growth patterns in Neolithic Liguria (northwestern Italy)

OBJECTIVE

This study evaluates patterns of human growth in the Neolithic to make inferences about environmental correlates of developmental disturbances.

MATERIALS

33 children/adolescents from the Neolithic of Liguria (Italy), 29 of which date between 4,800-4,400 cal BCE.

METHODS

Neolithic patterns of growth are compared with a modern sample (the Denver Growth Study; DGS). Dental development was used to determine age at death. Proxies for postcranial maturation are femoral length and proportion of mean adult femoral length attained.

RESULTS

Ligurian children show growth faltering compared to DGS, especially between 4 and 9 years of age. Between 1 and 2 years, and in later childhood and adolescence, values are more similar or higher than DGS, when using the proportion of adult femoral length attained.

CONCLUSIONS

The pattern of growth in Ligurian Neolithic children may reflect a deprived and highly-infectious environment: three individuals show skeletal lesions consistent with tuberculosis. The relatively faster growth in infancy may result from the buffering provided by maternal milk. Older children and adolescents may exhibit catch-up growth.

SIGNIFICANCE

This study contributes to our understanding of Neolithic selective pressures and possible biocultural adaptive strategies.

LIMITATIONS

The cross-sectional nature of the data and the small sample size make it unclear whether the observed pattern is representative of the growth patterns in the living population. The possibility that adults are stunted undermines the interpretation of optimal growth in the first years.

SUGGESTIONS FOR FURTHER RESEARCH

Refine age estimates, increase sample size through the study of other bone elements.

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.

Femoral neck and shaft structure in Homo naledi from the Dinaledi Chamber (Rising Star System, South Africa)

The abundant femoral assemblage of Homo naledi found in the Dinaledi Chamber provides a unique opportunity to test hypotheses regarding the taxonomy, locomotion, and loading patterns of this species. Here we describe neck and shaft cross-sectional structure of all the femoral fossils recovered in the Dinaledi Chamber and compare them to a broad sample of fossil hominins, recent humans, and extant apes. Cross-sectional geometric (CSG) properties from the femoral neck (base of neck and midneck) and diaphysis (subtrochanteric region and midshaft) were obtained through CT scans for H. naledi and through CT scans or from the literature for the comparative sample. The comparison of CSG properties of H. naledi and the comparative samples shows that H. naledi femoral neck is quite derived with low superoinferior cortical thickness ratio and high relative cortical area. The neck appears superoinferiorly elongated because of two bony pilasters on its superior surface. Homo naledi femoral shaft shows a relatively thick cortex compared to the other hominins. The subtrochanteric region of the diaphysis is mediolaterally elongated resembling early hominins while the midshaft is anteroposteriorly elongated, indicating high mobility levels. In term of diaphyseal robusticity, the H. naledi femur is more gracile that other hominins and most apes. Homo naledi shows a unique combination of characteristics in its femur that undoubtedly indicate a species committed to terrestrial bipedalism but with a unique loading pattern of the femur possibly consequence of the unique postcranial anatomy of the species.

Maintaining mobility after fracture: A biomechanical analysis of fracture consequences at the Roman Sites of Ancaster (UK) and Vagnari (Italy)

OBJECTIVE

This study uses biomechanical data from tibiae to investigate the functional consequences of lower limb fractures. Adults with malunited fractures are hypothesized to have experienced altered mobility, indicated by asymmetric tibial cross-sectional geometries (CSG).

MATERIALS

Ninety-three adults from Roman (1st to 4th centuries CE) Ancaster, UK and Vagnari, Italy (Ancaster n = 16 adults with lower limb fracture:53 without fracture; Vagnari n = 5:19) METHODS: Biplanar radiographs were used to quantify and compare tibial CSG properties and asymmetries between individuals with and without fractures to femora, tibiae, and/or fibulae. The amount of angulation, rotation, and overlap, indicative of linear deformity, were measured for each fracture. Individuals who loaded their fractured leg differently than their opposite, uninjured leg were identified using outlying amounts of CSG asymmetry.

RESULTS

Two Ancaster individuals had poorly aligned fractures. None of the Ancaster or Vagnari individuals with lower limb fractures had CSG properties or asymmetries outside the calculated normal ranges.

CONCLUSIONS

Regardless of how a fracture healed, individuals at Ancaster and Vagnari generally resumed mobility after trauma whenever possible.

SIGNIFICANCE

This research contributes information about injury recovery and suggests that resilient behaviors and persistent mobility may have been valued or required responses to fracture in the study communities. This work advises that impairment should not be inferred based solely on the appearance of lesions.

LIMITATIONS

Site, sex, and age patterns in injury recovery are not evaluated due to sample size limitations.

SUGGESTIONS FOR FURTHER RESEARCH

Biomechanical assessments of post-traumatic function in varied cultural contexts are advised in order to further characterize the impact that physical and social factors have on injury recovery.

The impact of terrain on lower limb bone structure

OBJECTIVES

Lower limb diaphyseal geometry is often used to evaluate mobility in past populations. Diaphyseal dimensions such as high shape (I_X /I_Y ) indices generally thought to reflect high mobility may also result from walking over rough terrain. This study investigates the possible effects of terrain on lower limb diaphyseal cross-sectional geometric dimensions.

MATERIALS

The sample (N = 3,195) comprises adult skeletons from Europe, Africa, North America, and Asia, spanning from around 30,000 BP to mid-twentieth century.

METHODS

Femoral and tibial shape and bending/torsional strength dimensions were gathered either as part of a previous project or were generously provided by researchers. Local terrain for each site was quantified with ArcGIS mapping software using geographic coordinates and USGS elevation data, and characterized as flat, hilly, or mountainous.

RESULTS

Analysis of variance shows significant differences (p < .05) in midshaft femoral and tibial shape ratio and relative bending/torsional strength among the three terrain categories, with more AP oriented diaphyseal shapes and greater relative strength in hilly and mountainous groups, even after correcting for the effect of subsistence. As expected, the impact of terrain is much more marked for hunter-gatherers and agriculturalists than for more mechanized recent populations. Interestingly, the effect of terrain is confounded in higher latitude individuals that exhibit increased ML bending strength, probably reflecting larger body breadth.

DISCUSSION

This study underscores the mechanical significance of traveling over rough terrain and highlights the complex interactions of mobility, terrain, and body shape that contribute to shaping lower limb bone diaphyseal structure.

Cross-sectional properties of the humeral diaphysis of Paranthropus boisei: Implications for upper limb function

A ∼1.52 Ma adult upper limb skeleton of Paranthropus boisei (KNM-ER 47000) recovered from the Koobi Fora Formation, Kenya (FwJj14E, Area 1A) includes most of the distal half of a right humerus (designated KNM-ER 47000B). Natural transverse fractures through the diaphysis of KNM-ER 470000B provide unobstructed views of cortical bone at two sections typically used for analyzing cross-sectional properties of hominids (i.e., 35% and 50% of humerus length from the distal end). Here we assess cross-sectional properties of KNM-ER 47000B and two other P. boisei humeri (OH 80-10, KNM-ER 739). Cross-sectional properties for P. boisei associated with bending/torsional strength (section moduli) and relative cortical thickness (%CA; percent cortical area) are compared to those reported for nonhuman hominids, AL 288-1 (Australopithecus afarensis), and multiple species of fossil and modern Homo. Polar section moduli (Z_p) are assessed relative to a mechanically relevant measure of body size (i.e., the product of mass [M] and humerus length [HL]). At both diaphyseal sections, P. boisei exhibits %CA that is high among extant hominids (both human and nonhuman) and similar to that observed among specimens of Pleistocene Homo. High values for Z_p relative to size (M × HL) indicate that P. boisei had humeral bending strength greater than that of modern humans and Neanderthals and similar to that of great apes, A. afarensis, and Homo habilis. Such high humeral strength is consistent with other skeletal features of P. boisei (reviewed here) that suggest routine use of powerful upper limbs for arboreal climbing.

Exploring bone volume and skeletal weight in the Middle Pleistocene humans from the Sima de los Huesos site (Sierra de Atapuerca, Spain)

Body mass estimation in fossil human species is a crucial topic in paleoanthropology as it yields information about ecologically relevant characteristics. Nevertheless, variables crucial to body mass estimation such as bone volume and skeletal weight have never before been calculated in a fossil human species. The exceptional state of preservation of several fossil human long bones from the Sima de los Huesos (SH) Middle Pleistocene site, in the Sierra de Atapuerca, makes it possible to calculate for the first time the absolute bone volume in five complete long bones (two femora and three humeri) of a fossil human species, an approach not possible in fragmentary or poorly preserved fossils. We have relied on computed tomography scans and 3D reconstructions to calculate bone volume. A sample of 62 complete bones of robust recent humans was also used for comparative purposes. The male SH femora (weight-bearing bones) and humeri (non-weight-bearing bones) have, relative to their size, greater bone volume (volume of bone tissue over total bone volume) than the equivalent bones in our recent human sample. As mass is volume × density, and bone tissue density (as a material) is similar across mammals, we calculate bone mass, and our results show that the SH hominins had on average heavier long bones than extant humans of the same size. From the femoral weight at hand, we have estimated the total skeletal weight in two SH individuals, which is about 36% heavier than in the recent humans of the equivalent body size. Using different methods and skeletal variables, including skeletal weight, to estimate body mass in these two SH humans, we highlight the considerable differences in body mass estimates we obtained, and that the largest body mass estimate is the one based on the skeletal weight. Our results suggest that we cannot assume the same relative proportion of bone volume and bone and skeletal weight characterized the entire genus Homo. Given that skeletal weight has a significant influence on body mass, current body mass estimates of fossil Homo specimens could be systematically underestimated. Thus, the significantly larger bone volume and heavier bones, probably throughout the entire skeleton, of SH humans could have had consequences for many biological parameters in this Pleistocene population and considerable importance for studies focusing on adaptive and ecologically relevant characteristics. Although more recent human samples should be analyzed, in our view, the high skeletal robusticity of the SH sample, including larger bone volume and skeletal weight, is part of their adaptive body type selected for throughout the Pleistocene to support different mechanical and activity regimes and formed under tight genetic control, including control over bone formative and regulatory processes.

Bilateral asymmetry of the humerus in Neandertals, Australian aborigines and medieval humans

OBJECTIVES

Bilateral asymmetry of diaphyseal shape and size may be a reflection of relative activity levels and patterns of habitual biomechanical stress in the upper arms of Neandertals and Homo sapiens. The main purpose of our study was to assess the level of directional asymmetry of humeral cross sections in Neandertals, recent Australian aborigines, and medieval farmers.

MATERIALS AND METHODS

Indices of directional and absolute asymmetry (%DA and %AA) of humeral cross-sectional properties in Neandertals and recent Homo sapiens were calculated. Evenly distributed semilandmarks around the external and internal borders of cortical bone were digitized in the course of computed tomography for analysis of shape differences between sides of the body.

RESULTS

The medieval farmers were characterized by significant %DA and %AA for polar second moment of area (J), ratio of maximum to minimum second moments of area, and ratio of antero-posterior to medio-lateral bending strength. In Australian aborigines, only J in males shows significant %DA and %AA, while Neandertals exhibit no significant asymmetry of any cross-sectional properties. Differences in cross-sectional shape between sides of the body were established in all three analyzed groups.

DISCUSSION

High levels of directional asymmetry of cross-sectional shape and properties in medieval farmers may be caused by the performance of more physically demanding tasks using one side of the body from an early age in that population. Various patterns of asymmetry in Neandertals and modern humans may be caused by different habitual behaviors during growth, eco-geographic patterns in body proportions, genetic factors, and differences in ontogeny.

Smaller long bone cross-sectional size in people who died of tuberculosis: Insights on frailty factors from a 19th and early 20th century Finnish population

There is little research on how individuals suffering from tuberculosis may differ from those not infected in terms of overall skeletal morphology. Tuberculosis was endemic in 19th and early 20th century Finland making documented skeletal collections of Finns ideal to study effects of the disease on bone. The present study compares long bone cross-sectional total area between individuals who died of tuberculosis and those with another recorded cause of death in a Finnish sample. Adult male individuals (N = 105) were selected for analysis. Complete humeri (N = 56), femora (N = 66) and tibiae (N = 64) were 3D scanned using a laser scanner and total cross-sectional areas calculated with AsciiSection software. Individuals who died of tuberculosis (N = 24, 15 humeri, 14 femora, 13 tibiae) had, when standardized for body size, significantly smaller total cross-sectional femoral and humeral, but not tibial, areas. The mechanisms behind the observed relationship may reflect a combination of biological 'frailty' in terms of susceptibility to infection, reduced childhood activity and/or vitamin D deficiency, which possibly influenced both subperiosteal development during adolescence and, later, susceptibility to contracting and dying of TB. Due to the relatively small sample future studies are needed to further investigate the relationship between TB and bone cross-sectional size.

Prehistoric women's manual labor exceeded that of athletes through the first 5500 years of farming in Central Europe

The intensification of agriculture is often associated with declining mobility and bone strength through time, although women often exhibit less pronounced trends than men. For example, previous studies of prehistoric Central European agriculturalists (~5300 calibrated years BC to 850 AD) demonstrated a significant reduction in tibial rigidity among men, whereas women were characterized by low tibial rigidity, little temporal change, and high variability. Because of the potential for sex-specific skeletal responses to mechanical loading and a lack of modern comparative data, women's activity in prehistory remains difficult to interpret. This study compares humeral and tibial cross-sectional rigidity, shape, and interlimb loading among prehistoric Central European women agriculturalists and living European women of known behavior (athletes and controls). Prehistoric female tibial rigidity at all time periods was highly variable, but differed little from living sedentary women on average, and was significantly lower than that of living runners and football players. However, humeral rigidity exceeded that of living athletes for the first ~5500 years of farming, with loading intensity biased heavily toward the upper limb. Interlimb strength proportions among Neolithic, Bronze Age, and Iron Age women were most similar to those of living semi-elite rowers. These results suggest that, in contrast to men, rigorous manual labor was a more important component of prehistoric women's behavior than was terrestrial mobility through thousands of years of European agriculture, at levels far exceeding those of modern women.

Diachronic changes in size and shape of human proximal tibia in Central Europe during the latest 1200 years

During the past twelve centuries, the stature of Central European inhabitants has increased significantly with corresponding changes in the size of lower limb bones. The aim of our study was to determine whether these changes have occurred strictly in relation to size or if the shape of skeletal structures has been altered simultaneously. Diachronic size and shape changes in the proximal part of tibia in a Central European population (Czech Republic) were studied using geometric morphometrics (principal components analysis, Hotelling's test, linear discriminant analysis). The study sample consisted of 183 three-dimensional (3D) models of adult tibiae dating to the early Middle Ages (N=65), early 20th century (N=60), and from a modern Czech population (N=57). A positive secular trend in size manifested only between the two modern Czech populations (the 20th century vs. the 21st century), a time range shorter than one century. By contrast, landmark-based shape analyses revealed significant differences in tibial morphology over the three periods covered in the study. In particular, progressive changes were observed in the position of tibial tuberosity (shifted medially), the inclination of the line connecting tuberosity with anterior edge of the tibial plateau (sloped down), the reshaping of the lower back condyle boundary (shifted posteriorly), and reshaping of the medial contour of the medial condyle (shifted anteriorly). Changes in the shape of the proximal tibial extremity across the chronologically distinct groups indicated the existence of discreet but convincing microevolutionary trends involving this anatomical structure.

The impact of subsistence changes on humeral bilateral asymmetry in Terminal Pleistocene and Holocene Europe

Analyses of upper limb bone bilateral asymmetry can shed light on manipulative behavior, sexual division of labor, and the effects of economic transitions on skeletal morphology. We compared the maximum (absolute) and directional asymmetry in humeral length, articular breadth, and cross-sectional diaphyseal geometry (CSG) in a large (n > 1200) European sample distributed among 11 archaeological periods from the Early Upper Paleolithic through the 20(th) century. Asymmetry in length and articular breadth is right-biased, but relatively small and fairly constant between temporal periods. Females show more asymmetry in length than males. This suggests a low impact of behavioral changes on asymmetry in length and breadth, but strong genetic control with probable sex linkage of asymmetry in length. Asymmetry in CSG properties is much more marked than in length and articular breadth, with sex-specific variation. In males, a major decline in asymmetry occurs between the Upper Paleolithic and Mesolithic. There is no further decline in asymmetry between the Mesolithic and Neolithic in males and only limited variation during the Holocene. In females, a major decline occurs between the Mesolithic and Neolithic, with resulting average directional asymmetry close to zero. Asymmetry among females continues to be very low in the subsequent Copper and Bronze Ages, but increases again in the Iron Age. Changes in female asymmetry result in an increase of sexual dimorphism during the early agricultural periods, followed by a decrease in the Iron Age. Sexual dimorphism again slightly declines after the Late Medieval. Our results indicate that changes in manipulative behavior were sex-specific with a probable higher impact of changes in hunting behavior on male asymmetry (e.g., shift from unimanual throwing to use of the bow-and-arrow) and food grain processing in females, specifically, use of two-handed saddle querns in the early agricultural periods and one-handed rotary querns in later agricultural periods.

Divergence in male and female manipulative behaviors with the intensification of metallurgy in Central Europe

Humeral morphology has been shown to reflect, in part, habitual manipulative behaviors in humans. Among Central European agricultural populations, long-term social change, increasing task specialization, and technological innovation all had the potential to impact patterns of habitual activity and upper limb asymmetry. However, systematic temporal change in the skeletal morphology of agricultural populations in this region has not been well-characterized. This study investigates diachronic patterns in humeral biomechanical properties and lengths among 174 adult Central European agriculturalists through the first ∼ 5400 years of farming in the region. Greater asymmetry in biomechanical properties was expected to accompany the introduction of metallurgy, particularly in males, while upper limb loading patterns were expected to be more similar between the Bronze and Iron Ages. Results revealed a divergence in the lateralization of upper limb biomechanical properties by sex between the Early/Middle Neolithic and Early/Middle Bronze Age. Neolithic females had significantly more variable properties than males in both humeri, while Bronze Age female properties became homogeneous and very symmetrical relative to the right-biased lateralization of contemporaneous males. The Bronze Age to Iron Age transition was associated with morphological change among females, with a significant increase in right-biased asymmetry and a concomitant reduction in sexual dimorphism. Relative to biomechanical properties, humeral length variation and asymmetry were low though some significant sexual dimorphism and temporal change was found. It was among females that the lateralization of humeral biomechanical properties, and variation within them, changed most profoundly through time. This suggests that the introduction of the ard and plow, metallurgical innovation, task specialization, and socioeconomic change through ∼ 5400 years of agriculture impacted upper limb loading in Central European women to a greater extent than men.

The influence of relative body breadth on the diaphyseal morphology of the human lower limb

OBJECTIVES

Variation in relative body breadth between individuals is potentially a significant influence on the biomechanical loading placed upon the lower limb. This study investigates the influence of relative body breadth on the periosteal geometry of the diaphyses of the limb bones among individuals from a broad range of human populations.

METHODS

This study applies a 3D laser scanning approach to the extraction and analysis of periosteal cross-sectional properties throughout the diaphyses of the femur and tibia to test for influences of body shape on diaphyseal morphology throughout the lower limb. Analyses are based on data collected from seven populations, encompassing a broad range of modern human variation in body shape.

RESULTS

Hypertrophy of the proximal end of the femur diaphysis in wider bodied individuals is observed and appears to extend at least as far as the femur midshaft, while the mid diaphyseal region of the tibia is the least influenced by body shape. However correlations with relative body breadth were also observed towards the distal end of the femur diaphysis and towards both ends of the tibial diaphysis, especially among females.

CONCLUSIONS

Relative body breadth is correlated with the periosteal geometry of the lower limb bones, particularly towards the proximal end of the femur diaphysis, but correlations in other regions also suggest integration of the diaphyseal geometry with epiphyseal dimensions.

Subsistence strategy changes: the evidence of entheseal changes

Changes in subsistence strategy have caused some of the profoundest changes to the structure and health of humans. This study aims to test whether these changes have reduced work-load as assessed by entheseal changes. Entheseal changes, formerly called musculoskeletal stress markers, are thought to reflect muscle usage throughout life, although it is widely agreed that they have a multifactorial origin. This paper uses a meta-analysis of comparable published data to plot trends in time by muscle, enthesis type and sex. The results show that agriculturalists have the lowest scores for entheseal changes, with hunte-gatherers next highest and those working in industry the highest. These findings are the same for males and females, for most muscles and muscle groups. However, entheseal changes are highly correlated with increased age and the age distributions of the samples analysed could not be compared. It is, therefore, possible that differences in age distribution of the samples are one of the reasons for this finding. Recommendations are provided to reduce this and other limitations for future meta-analyses.

The importance of accounting for the area of the medullary cavity in cross-sectional geometry: A test based on the femoral midshaft

In cross-sectional geometric (CSG) studies, both the subperiosteal and endosteal contours are considered important factors in determining bone bending rigidity. Recently, regression equations predicting CSG properties from a section's external dimensions were developed in a world-wide sample of human long bones. The results showed high correlations between some subperiosteally derived and actual CSG parameters. We present a theoretical model that further explores the influence of endosteal dimensions on CSG properties. We compare two hypothetical femoral midshaft samples with the same total subperiosteal area but with percentages of cortical bone at the opposite ends of published human variation for population sample means. Even in this relatively uncommon scenario, the difference between the samples in the resultant means for predicted femoral polar second moment of area (J) appears to be modest: power analysis indicates that a minimum sample size of 61 is needed to detect the difference 90% of the time via a t-test. Moreover, endosteal area can be predicted--although with substantial error--from periosteal area. Despite this error, including this relationship in subperiosteally derived estimates of J produces sample mean estimates close to true mean values. Power analyses reveal that when similar samples are used to develop prediction equations, a minimum sample of hundreds or more may be needed to distinguish a predicted mean J from the true mean J. These results further justify the use of regression equations estimating J from periosteal contours when analyzing behaviorally induced changes in bone rigidity in ancient populations, when it is not possible to measure endosteal dimensions. However, in other situations involving comparisons of individual values, growth trends, and senescence, where relative cortical thickness may vary greatly, inclusion of endosteal dimensions is still important.

The influence of body proportions on femoral and tibial midshaft shape in hunter-gatherers

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

Changes in skeletal robusticity in an iron age agropastoral group: the Samnites from the Alfedena necropolis (Abruzzo, Central Italy)

Cross-sectional geometrical (CSG) properties of an Iron Age Samnite group from the Alfedena necropolis (Abruzzo, Italy, 2600-2400 B.P.) are compared with a Ligurian Neolithic sample (6000-5500 B.P.). In the period under examination, Samnites were organized in a tribal confederation led by patrilinear aristocracies, indicating incipient social stratification. In comparison, Neolithic society lacked clear signs of social hierarchy. The subsistence of both groups was mainly based on pastoralism and agriculture, but changes in habitual behavior are expected due to the socio-economic transformations that characterized the Iron Age. The Samnites' warlike ideology suggests that unimanual weapon-use and training would have become frequent for males. The intensification of agriculture and the adoption of transhumant pastoralism, performed by a smaller subset of the population, likely led to a lower average level of logistic mobility. The strongly genderized ideology of the period suggests a strict sexual division of labor, with women primarily performing sedentary tasks. CSG properties based on periosteal contours were calculated for humeri, femora, and tibiae (N = 61). Results corroborated the expectations: Alfedena males show substantial humeral bilateral asymmetry, indicating prevalent use of one arm, likely due to weapon training. In both sexes lower limb results indicate reduced mobility with respect to the Neolithic group. Sexual dimorphism is significant in both humeral asymmetry and lower limb indicators of mobility. Although both groups could be broadly defined as agropastoral based on archeological and historical evidence, CSG analysis confirmed important differences in habitual behavior.

Habitual throwing and swimming correspond with upper limb diaphyseal strength and shape in modern human athletes

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

Sex differences in humeral bilateral asymmetry in two hunter-gatherer populations: California Amerinds and British Columbian Amerinds

This study uses two prehistoric Amerindian populations of hunter-gatherer subsistence patterns to determine whether levels of sexual dimorphism in humeral bilateral cross-sectional asymmetry are related to sex-specific differences in activities among these populations. Results confirmed that males of the California Amerind population who engaged in the more unimanual activities of spear hunting and warfare were more asymmetrical than were their female counterparts who engaged in the more bimanual activities of grinding acorns. California Amerind males were also more asymmetrical than British Columbian Amerind males who rowed (using both arms) extensively. Sex differences within British Columbian Amerinds were not statistically significant, nor were female differences between populations. In general, levels of humeral asymmetry appear to be more dependent on sex and population-specific behaviors rather than broad subsistence patterns.