Doctoral Dissertation Research: Life history tradeoffs affecting bone maintenance and development in women

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Bone is a dynamic tissue that changes through the lifespan. This dissertation research will combine markers of bone turnover with measures of bone density to understand how bone varies with physical activity and life history. The project seeks to understand the slow change in bone density and the processes that maintain bone turnover, in two related populations with different lifestyles. In addition to data on estrogen and physical activity levels, the co-PI will collect information on age at menarche, number of offspring, and duration of breastfeeding, which are life history traits that can vary with energy availability and stress levels, reflect changing estrogen concentrations, and may correlate with bone characteristics. Combining data on past conditions and current lifestyle factors in this comparative context will expand our understanding bone health through the lifecourse in adult women. The project will also promote international collaborations, student training and mentoring, and public science outreach activities. This project builds upon previous work in life history and human reproductive ecology and applies these approaches to analyses of bone health. Using these paradigms for interpreting female reproductive endocrinology in ecological and evolutionary contexts, this research focuses on bone as a product of the hormonal, energetic, and mechanical demands of the human female across the lifespan. Integrating the bone-related effects of physical activity across multiple physiological systems is important because they do not operate independently of one another. By comparing physical activity levels, current estrogen concentrations, and life history variables between Polish women and second and third generation Polish-American women, this research will test hypotheses about the ways in which life history, physical activity, and the estrogen-mediated interactions between these variables affect bone density and turnover in healthy adult women. This work extends the life history concept of resource allocation to include bone maintenance as one of the tradeoffs between growth, maintenance, and reproduction. Additionally, it contributes to broader anthropological discussions regarding health effects of demographic transitions to sedentary industrialized lifestyles.