The Interaction of Mechanical Loading and Metabolic Stress on Human
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University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 8-2013 THE INTERACTION OF MECHANICAL LOADING AND METABOLIC STRESS ON HUMAN CORTICAL BONE: TESTING ANTHROPOLOGICAL ASSUMPTIONS USING CROSS-SECTIONAL GEOMETRY AND HISTOMORPHOLOGY Courtney Dianne Eleazer [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Recommended Citation Eleazer, Courtney Dianne, "THE INTERACTION OF MECHANICAL LOADING AND METABOLIC STRESS ON HUMAN CORTICAL BONE: TESTING ANTHROPOLOGICAL ASSUMPTIONS USING CROSS-SECTIONAL GEOMETRY AND HISTOMORPHOLOGY. " PhD diss., University of Tennessee, 2013. https://trace.tennessee.edu/utk_graddiss/2420 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Courtney Dianne Eleazer entitled "THE INTERACTION OF MECHANICAL LOADING AND METABOLIC STRESS ON HUMAN CORTICAL BONE: TESTING ANTHROPOLOGICAL ASSUMPTIONS USING CROSS-SECTIONAL GEOMETRY AND HISTOMORPHOLOGY." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Anthropology. Benjamin M. Auerbach, Major Professor We have read this dissertation and recommend its acceptance: Graciela Cabana, Andrew Kramer, Katie Kavanagh Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) THE INTERACTION OF MECHANICAL LOADING AND METABOLIC STRESS ON HUMAN CORTICAL BONE: TESTING ANTHROPOLOGICAL ASSUMPTIONS USING CROSS-SECTIONAL GEOMETRY AND HISTOMORPHOLOGY A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Courtney Dianne Eleazer August 2013 ACKNOWLEDGEMENTS As is true of all doctoral candidates, I could not have accomplished this goal without the assistance and support of others. Those who have contributed to this research project, whether in an academic context or in the form of emotional support, deserve enormous credit for their efforts. First, I would like to thank Ben Auerbach for his role in helping to shape this work. Ben accepted me as his first graduate student at the University of Tennessee knowing that my dissertation project would be a challenging endeavor (for both of us), and through these last six years he has met every bump in the road with exceptional optimism and encouragement. I am incredibly lucky to have had such a supportive and involved academic advisor and committee chair. I would also like to thank the remaining members of my committee: Graciela Cabana, Andy Kramer, and Katie Kavanagh, for providing insightful comments and advice that improved this research. Graciela has provided much guidance on the project’s design, specifically the formulation of the research hypotheses and the broader implications to the anthropological discipline. She also graciously allowed me to cut samples and store equipment in her molecular anthropology lab. In addition, Andy and Katie’s broad knowledge of mechanics and nutrition have helped structure my approach to interpreting these effects in archaeological samples. Together, the perspectives of my committee members have helped develop the project in ways that I would have not considered, and I am much appreciative of their guidance. I would like to especially thank those researchers and colleagues not on my committee who have provided me with access to collections and resources as well as advice, without which ii this research would not have been possible. I am forever indebted to Tosha Dupras. In addition to providing me with bone samples from Egypt (Kellis 2 cemetery, Dakhleh Oasis) for my pilot project and granting me permission to continue research at that site, she was integral to locating another cemetery sample when the Egyptian revolution prevented access to the Kellis skeletal remains and thwarted progress on this project. When it appeared that no other subadult skeletal collection was available for histological analysis, Tosha made it her mission to assist with finding a collection for me to conduct my research and placed me in contact with the Faculty of Medicine at Vilnius University. Without her assistance, it is likely that I would have had to abandon the project entirely. I also wish to express my sincere gratitude to Rimantas Jankauskas, the curator of skeletal collections at the Vilnius University, for granting me access to the Alytus skeletal collection. Rimantas was always willing to go above and beyond in providing assistance and information. Thank you also to Agnius Urbanavicius and Justina Kozakaite for pulling boxes during data collection in Vilnius and allowing me to disturb their carefully curated collection. Agnius also took time out of his summer vacation to show me around his hometown of Alytus and pass along his knowledge of Alytus history, and for this I am incredibly grateful. Several doctoral students at Vilnius University aided with procuring bone samples as well. Lana Williams shared her extensive expertise in photographing pathological lesions and alleviated some of the burden of data collection by offering to photograph some pathologies herself. I extend my deepest appreciation to Walter Klippel for allowing me to utilize histological equipment and supplies in the Mineralized Tissue Histology Laboratory and Zooarchaeology Laboratory at the University of Tennessee. Thank you also to the Department of Anthropology for funding a portion of this project through the Kneberg-Lewis Award. Additionally, I wish to iii thank those researchers (in no particular order) whose ideas have helped shape my own and with whom I have had many insightful conversations over the years about my research: Libby Cowgill, Evan Garofalo, Valerie DeLeon, Robert Paine, Margaret Streeter, Susan Pfeiffer, Sam Stout, Danny Wescott, Dan Temple, Osborn Pearson, David Burr, and Chris Ruff. I am immensely indebted to my family and friends who have supported me through this entire process. There are no words to express how much my parents have contributed to my academic career and how appreciative I am of their love and support. They have always supported me in my decisions and endeavors throughout my life. My brother, Ben, is about to embark on this same journey and I intend to provide him with the same encouragement (and bitter sarcasm/teasing) as he has bestowed on me. My best friend and platonic life partner, Linz, has been by my side throughout my college and graduate school years. Above all things, she has taught me how to laugh and not take myself too seriously. Thanks also to my in-laws—Rick, Jan, Joe, Katy, and Daniel—for accepting me into their family and being so understanding and supportive of my career goals. To my fellow graduate students and ladies of the OVAL (Becky Kelso, Nicole Reeves, Amber Wheat, Brannon Hulsey, Frankie Pack, Hillary Parsons, Beatrix Dudzik), were it not for you I would have gone completely insane. Thank you for making me smile no matter the circumstances and being patient while I obsessed about osteons and cross-sections. You all have given me an incredible amount of academic and personal advice that I will continue to employ for years to come. All of you are beautiful, amazing women who have influenced and enriched my life more than you probably realize. iv And finally, I especially thank my husband, Andrew Weidman, for having unwavering faith in me. Andrew, you are my rock. Thank you for taking care of me (and the house) and always being there for me. I couldn’t have accomplished this goal without your help. v ABSTRACT 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 properties were compared among individuals who had experienced varying amounts of metabolic stress, as inferred from skeletal stress lesions. Analyses tested the hypothesis that to maintain proper bone strength, metabolic stress effects (i.e., bone loss) are increasingly attenuated as mechanical loading demands increase across the three skeletal elements. Results suggest that mechanical loading compensates for metabolic bone loss at both macroscopic and microscopic scales. Macroscopically, loading attenuates metabolic bone loss by