Mechanical and Metabolic Interactions in Cortical Bone Development (original) (raw)
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This research investigates how the interaction of mechanics (i.e., physical activity) and metabolism (i.e., health status) shapes human cortical bone morphology during skeletal development. Understanding this interaction is important for research investigating human behavior from adult and subadult archaeological skeletal samples, as previous studies have demonstrated that interaction effects may confound the interpretation of either mechanics or metabolism independently from skeletal remains. This study approaches this issue holistically through the analysis of human cortical bone morphology at dual scales (microscopic and macroscopic scales) and across multiple skeletal elements (femora, humeri, and ribs) exposed to different levels of mechanical loading. Because bone responds to environmental influences most strongly during growth, a subadult cemetery sample of 57 individuals from the medieval archaeological site of Alytus, Lithuania (A.D. 14th-18th centuries) was employed. Bone ...
American Journal of Physical Anthropology
The second millennium BC was a period of significant social and environmental changes in prehistoric India. After the disintegration of the Indus civilization, in a phase known as the Early Jorwe (1400–1000 BC), hundreds of agrarian villages flourished in the Deccan region of west-central India. Environmental degradation, combined with unsustainable agricultural practices, contributed to the abandonment of many communities around 1000 BC. Inamgaon was one of a handful of villages to persist into the Late Jorwe phase (1000–700 BC), wherein reliance on dry-plough agricultural production declined. Previous research demonstrated a significant decline in body size (stature and body mass index) through time, which is often used to infer increased levels of biocultural stress in bioarchaeology. This article assesses evidence for growth disruption in the immature human skeletal remains from Inamgaon by correlating measures of whole bone morphology with midshaft femur compact bone geometry and histology. Growth derangement is observable in immature archaeological femora as an alteration in the expected amount and distribution of bone mass and porosity in the midshaft cross-section. Cross-section shape matched expectations for older infants with the acquisition of bipedal locomotion. These results support the hypothesis that small body size was related to disruptions in homeostasis and high levels of biocultural stress in the Late Jorwe at Inamgaon. Further, the combined use of geometric properties and histological details provides a method for teasing apart the complex interactions among activity and “health,” demonstrating how biocultural stressors affect the acquisition and quality of bone mass.
Journal of Anthropological Archaeology, 2013
The aim of this study is to look at upper body functional modifications caused by mechanical loading. We look at 4th lumbar vertebra as well as fibrous humeral musculoskeletal stress markers (MSMs). This study uses information provided by magnetic resonance images of living individuals from the University of Oulu Hospital data banks (N = 91), archaeological skeletons from Sweden (N = 54) and England (N = 61), and autopsied skeletal collection of early 20th century Finns in Natural History Museum, University of Helsinki (N = 48). The lumbar vertebrae and MSM are subjected to mechanical loading caused by the upper body weight and loads lifted and/or carried. We hypothesized that the vertebral size reflect body size, habitual mechanical loading and the overall skeletal robusticity as mechanical competence to withstand mechanical loading standardized to body size, which has decreased over millennia. For Helsinki material occupation, age and sex is known and the material was used in Niinimäki (2011). In the study by Niinimäki (2011) MSM were found to be affected by the intensity of muscular action as well as body size and age. This study is reviewed here in light of re-analysis of the data to follow the current anatomical understanding of the entheses as well as viewing MSMs as a part of upper body functional complex. Only fibrous entheses were included in the re-analysis. Furthermore, due to small number of females where activity intensity could be assessed, females were dropped from the re-analysis. Our findings reveal that the size and shape of the 4th lumbar vertebra has changed significantly from medieval times through post-medieval to modern day affecting the biomechanical characteristics of the lumbar vertebrae, possibly making spine fractures increasingly common. MSM are affected by the skeletal robusticity and activity level, although age bias is significant after biological maturity, where results remained the same after the re-analysis. The close relationship between biomechanics and therefore skeletal modeling is clearly revealed by the extent to which the level of habitual mechanical loading reflects in our skeletal anatomy.
Gracility of the modern Homo sapiens skeleton is the result of decreased biomechanical loading
Proceedings of the National Academy of Science
The postcranial skeleton of modern Homo sapiens is relatively gracile compared with other hominoids and earlier hominins. This gracility predisposes contemporary humans to osteoporosis and increased fracture risk. Explanations for this gracility include reduced levels of physical activity, the dissipation of load through enlarged joint surfaces, and selection for systemic physiological characteristics that differentiate modern humans from other primates. This study considered the skeletal remains of four behaviourally diverse recent human populations and a large sample of extant primates to assess variation in trabecular bone structure in the human hip joint. Proximal femur trabecular bone structure was quantified from microCT data for 229 individuals from 31 extant primate taxa and 59 individuals from four distinct archaeological human populations representing sedentary agriculturalists and mobile foragers. Analyses of mass-corrected trabecular bone variables reveal that the forager populations had significantly higher bone volume fraction, thicker trabeculae, and consequently lower relative bone surface area compared with the two agriculturalist groups. There were no significant differences between the agriculturalist and forager populations for trabecular spacing, number, or degree of anisotropy. These results reveal a correspondence between human behavior and bone structure in the proximal femur, indicating that more highly mobile human populations have trabecular bone structure similar to what would be expected for wild nonhuman primates of the same body mass. These results strongly emphasize the importance of physical activity and exercise for bone health and the attenuation of age-related bone loss.
Bone Morphologies and Histories: Life Course Approaches in Bioarchaeology
The duality of the skeleton as both a biological and cultural entity has formed the theoretical basis of bioarchaeol-ogy. In recent years bioarchaeological studies have stretched the early biocultural concept with the adoption of life course approaches in their study design and analyses, making a significant contribution to how we think about the role of postnatal plasticity. Life course theory is a conceptual framework used in several scientific fields of biology and the social sciences. Studies that emphasize life course approaches in the examination of bone morphology in the past are united in their interrogation of human life as a result of interrelated and cumulative events over not only the timeframe of individuals, but also over generations at the community level. This article provides an overview of the theoretical constructs that utilize the life course concept, and a discussion of the different ways these theories have been applied to thinking about trajectories of bone morphology in the past, specifically highlighting key recent studies that have used life course approaches to understand the influence of growth, stress, diet, activity, and aging on the skeleton. The goal of this article is to demonstrate the scope of contemporary bioarchaeological studies that illuminate the importance of environmental and behavioral influence on bone morphology. Understanding how tra-jectories of bone growth and morphology can be altered and shaped over the life course is critical not only for bio-archaeologists, but also researchers studying bone morphology in living nonhuman primates and fossil primate skeletons. Am J Phys Anthropol 159:
Bone growth, limb proportions and non-specific stress in archaeological populations from Croatia
2013
Background: The effect of environmental factors and, in particular, non-specific stress on the growth patterns of limbs and other body dimensions of children from past populations is not well understood. Aims: This study assesses whether growth of mediaeval and post-mediaeval children aged between 0–11.5 years from Adriatic (coastal) and continental Croatia varies by region and by the prevalence and type of non-specific stress. Methods: Dental ages were estimated using the Moorrees, Fanning and Hunt (MFH) scoring method. Growth of long bone diaphyses (femur, tibia, humerus, radius and ulna) was assessed by using a composite Z-score statistic (CZS). Clavicular length was measured as a proxy for upper trunk width, distal metaphyseal width of the femur was measured as a proxy for body mass and upper and lower intra-limb indices were calculated. Differences between sub-sets sampled by (a) region and (b) active vs healed non-specific stress indicators and (c) intra-limb indices were tested by Mann--Whitney U-tests and Analysis of Covariance (ANCOVA). Results: Adriatic children attained larger dimensions-per-age than continental children. Children with healed stress lesions had larger dimensions-per-age than those with active lesions. No inter-regional difference was found in intra-limb indices. Conclusion: These findings highlight the complexity of growth patterns in past populations and indicate that variation in environmental conditions such as diet and differences in the nature of non-specific stress lesions both exert a significant effect on long bone growth.
Variation in cross-sectional indicator of femoral robusticity in Homo sapiens and Neandertals
Scientific Reports, 2022
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. The structure of a bone is optimized in accordance with altered loading regimes, as manifested in the specific morphology, the orientation of the trabecular networks, and the size and distribution of the osteons 1. However, the precise mechanism of mechanical signal detection is still investigated 1-3 especially given that each bone differs in terms of sensitivity to mechanical stimuli 4. Recently, most research has assessed limb bone organization using cross-sectional geometry, which is typically calculated from periosteal and endosteal contours of specific cross-sections 5-8. Due to the broader availability of CT and the development of semiautomated techniques, interpopulation comparisons on larger scales can now be carried out. Thus, cross-sectional geometry is being used to measure diaphyseal variables which characterize bending and torsional rigidity 9. According to Macintosh and Stock 10 , minimizing stress in cortical bone renders the postcranial skeleton (especially the lower limbs) highly reactive to changes in types and levels of mobility and activity patterns. This variability in bone morphology can be applied in paleontological and bioarchaeological research to reconstruct
Chapter 6. Aspects of human osteology and skeletal biology
2019
This chapter presents the results of three studies that were undertaken as part of the Beaker People Project (BPP), and which complemented the osteological work undertaken for the Beakers and Bodies Project as reported in Chapter 5. The first study examined the age and sex of 201 individuals that had been deemed suitable for isotopic analysis of dental enamel. The second examined tooth enamel defects in 12 juvenile skeletons, as an indicator of non-specific infant stress. The third was a craniometric study of skulls from the Peak District, designed to assess the validity of previous claims for a change in skull shape from dolichocephalic (long-headed) during the Neolithic, to brachycephalic (roundheaded) from the Chalcolithic onwards, and to explore the possible reasons for the observed differences. The chapter ends by considering the results of the craniometric study in the light of isotopic evidence suggesting a high incidence of non-local individuals within the Peak District data...
Mechanical loads and cortical bone geometry in healthy children and young adults
Bone, 2011
Muscle and bone form a functional unit. While muscle size is a useful surrogate of mechanical load on bone, the independent contributions to bone strength of muscle force, muscle size, gravitational load (body weight), and physical activity have not been assessed. 321 healthy participants (32% black, 47% male), age 5 to 35 years were assessed. Peak dorsiflexion muscle torque (ft-lbs) of the ankle was assessed using isometric dynamometry. Tibia peripheral quantitative computed tomography measures included polar section modulus (Zp, mm 3 ), periosteal and endosteal circumference (mm), cortical area (mm 2 ), and volumetric bone mineral density (vBMD, mg/cm 3 ) at the 38% site, and muscle cross-sectional area (CSA, mm 2 ) at the 66% site. Physical activity (average hours /week) was assessed by questionnaire. Log linear regression was used to assess determinants of muscle specific force (MSF; torque relative to muscle CSA) and Zp adjusted for age and tibia length. MSF was greater in blacks than whites (p < 0.05) and lower in females than males (p < 0.001). Zp was greater in blacks than whites (p = 0.002) in Tanner stages 1-4, but the difference was attenuated in Tanner 5 (interaction, p = 0.02), R 2 = 0.87. Muscle CSA, muscle torque, body weight, and physical activity were added to the model and each load covariate was independently and significantly (all p < 0.02) associated with Zp (R 2 = 0.92), periosteal circumference, and cortical area. Inclusion of these measures attenuated but did not eliminate the significant race differences. Only muscle CSA was positively associated with endosteal circumference, while none of the load covariates were associated with vBMD.
Age-Related Cortical Bone Maintenance and Loss in an Imperial Roman Population
"This article explores age- and sex-related patterns of cortical bone loss, assessed by radiogrammetry of the second metacarpal, from a skeletal sample excavated from the Imperial Roman port city of Velia (1st and 2nd century AD), to contribute to our understanding of health and disease during the Imperial period. Patterns of age- and sex-related bone loss and health at Velia are also compared with other historical samples and to modern clinical data. It was hypothesised that patterns of age- and sex-related bone loss in this wellrepresented Roman sample (n = 71) would mirror those reported in modern populations. Differences in the quantity of cortical bone between three age groups (18–29, 30–49 and 50+ years) are significant in both men and women; however, the pattern of bone loss differs between the sexes. Women show a gradual decline in bone quantity beginning in middle age, whereas men only lose bone in old age. However, there are no significant sex differences at any age group in the metacarpal cortical index. These findings suggest the hypothesis should be refuted because significant sex differences, particularly in old age, are an expected hallmark of bone loss in Western populations today. The possible biocultural and gender-related factors that may have contributed to the observed patterns of bone maintenance and loss at Velia are discussed."