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

Abstract

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.

Twenty‐first century bioarchaeology: Taking stock and moving forward

“…Further, when the human skeleton is viewed as forged by biocultural factors over the entire life course, adaptive responses in bone morphology emphasize a range of trajectories. For example, contextualized data on bone maintenance and aging in the archaeological record show that patterns of bone loss and functional adaptation do not always constitute predictable or normative patterns of aging or biological sex (Agarwal, 2021).…”

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

“…While it is likely that some of this variance is explained by growth trajectories, particularly with cross-sectional properties influenced by growth and development such as TA, CA, MA, and %CA, it is also likely that much of this variation is related to our limited explanatory variables. Systemic bone remodeling in long bones is likely modulated by epigenetic factors or biocultural aspects of life history, such as diet and/or nutritional stress, sex-gender, and reproductive history in additional to physical activity and mechanical loading (Agarwal, 2016(Agarwal, , 2021Delgado-Calle et al, 2012;Ghayor & Weber, 2016). Furthermore, it is common and widely accepted in bioarchaeological cross-sectional geometry studies to use known biocultural variables such as age and sex as explanatory variables because it is well-documented that they can influence bone robusticity and morphology (e.g., Holt et al, 2018;Macintosh et al, 2014;Miller et al, 2018).…”

Exploring associations between presence of skeletal indicators of disease and sub-adult mortality

“…Instead, bioarchaeological research into frailty has frequently drawn upon knowledge of contemporary epidemiological research to complement findings and aid interpretation, discussing interactions between factors such as infections and malnutrition which may increase mortality beyond that of either stressor occurring in isolation, especially in younger individuals (Lewis, 2010, Pilkington, 2013, Reitsema and McIlvaine, 2014, van Schaik et al, 2014, Novak, 2015, Snoddy et al, 2016, DeWitte, 2018, Hens et al, 2019. Use of modern epidemiological data may allow inference of drivers of disease and mortality, however caution is required as modern populations may not form adequate analogues for those of the past (Agarwal, 2021). This is especially pertinent where substantial social and technological differences are present and where it may not be possible to fully assess these factors in an archaeological collection (Vercellotti et al, 2014, Quade andGowland, 2020).…”