Zeininger-Dissertation-2013
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Copyright by Angel Diane Zeininger 2013 The Dissertation Committee for Angel Diane Zeininger Certifies that this is the approved version of the following dissertation: Ontogeny of Bipedalism: Pedal Mechanics and Trabecular Bone Morphology Committee: Liza Shapiro, Supervisor John Kappelman Denne Reed E. Christopher Kirk Jody Jensen Brian Richmond Ontogeny of Bipedalism: Pedal Mechanics and Trabecular Bone Morphology by Angel Diane Zeininger, B.S.; M.A. Dissertation Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy The University of Texas at Austin December 2013 Dedication For Roscoe, Aiden River, and Siena Rose. May you walk the path less traveled. Acknowledgements Completion of this dissertation was facilitated with the help of many people at various institutions over the course of many years. I have had the great fortune of working with some of the most considerate and dedicated mentors in the field of physical anthropology and would like to take this opportunity to thank them in turn. Applying to work with my dissertation advisor, Liza Shapiro, was the best decision I could have made. A good relationship between a graduate student and an advisor is essential for the intellectual growth of the student, and I could not have asked for a more understanding and generally awesome advisor than Liza. Liza gave me a chance and believed in me, even when I questioned myself, and I can only hope that I lived up to her expectations. From my Masters through my dissertation, Liza encouraged me to develop projects about which I was passionate but that were also reasonable and within her expertise. Liza challenged me to find the significance in my work and to always consider the bigger evolutionary picture. I thank Liza for her always honest, yet often blunt, comments, edits, and questions. Mostly, I would like to thank Liza for her never ending support throughout the emotional roller coaster that is grad school. Liza is more than just an academic advisor, she is a friend to me, my family, and all of the UT physical anthropology graduate students. In short, thank you Liza, for all of your help, sage advice, support, encouragement, and dedication that you bring to the entire UT physical anthropology graduate program. I credit Brian Richmond (Center for the Advanced Study of Hominid Paleobiology, George Washington University) for suggesting the physical anthropology graduate program at the University of Texas at Austin and in specific, for recommending v that I consider working with Liza Shapiro and John Kappelman. As my undergraduate thesis advisor, Brian first sparked my interest in trabecular bone morphology and coordinated my first trabecular bone study. More than anything, Brian has taught me the value of persistence. As my eventual co-author and dissertation committee member, Brian has offered his intellect, support, and encouragement for the past thirteen years. I thank Jody Jensen (Department of Kinesiology and Health Education, Univeristy of Texas at Austin) for teaching me kinematic and kinetic data analysis and for graciously offering her Developmental Motor Control Laboratory for biomechanical data collection. In addition, Jody helped me develop the methods for, and statistically analyze the results of, my toddler walking study. Jody’s graduate students, Renate van Zandjwick and Rachel Hector were an invaluable resource when I had technical difficulties in the lab. Renate also went out of her way to recover and send me my original toddler walking trials following two catastrophic external hard drive failures in which I lost all of the analyzed data. Biomechanical data collection would not have been possible without the eighteen toddlers and their parents who volunteered to bring them in for participation in my study. I would also like to thank my wonderful and selfless graduate and undergraduate assistants who helped me escort parents and kids to and from the lab, entertain the toddlers during marker placement and removal, encourage toddlers to walk across the force plate, and run the computer during trials: Amber Heard-Booth, Kelly Manriquez, Graham Noblit, and Perla Santillan. I appreciate all of your time and help! I thank John Kappelman for encouraging me to improve my writing and presentation skills, for his understanding and offer of a TAship when I needed to work from home, and for his thoughtful discussions on how to choose my skeletal sample and analyze my foot bone scans. I am grateful to Denne Reed for his positive encouragement, vi for teaching me the value of creating a database, and for his statistical genius. Moreover, I thank both John and Denne for facilitating future access to Australopithecus afarensis fossil foot bones. I am grateful to Chris Kirk for his insightful comments, advice, and his always entertaining and inspirational lectures. I thank curators Eileen Westwig of the American Museum of Natural History as well as Linda Gordon and Darrin Lunde of the Smithonian Institution’s National Museum of Natural History for access to their primate skeletal collections. Additionaly, I thank George Milner of the Pennsylvania State University for access to his original notes and for allowing me to scan human foot bones from the Norris Farms Cemetary skeletal collection. Thank you to Tim Ryan of the Pennyslvania State University for providing pilot data, CT scanning the human foot bones, and for many discussions about how to best analyze the scans. I am grateful to Matt Colbert, Rich Ketcham, and Jessie Maisano of the University of Texas at Austin CT facility for scanning my primate foot bone sample and preparing my CT scans. I am especially appreciative of all of Matt’s advice on scan settings and analysis. Previous and current UT Austin physical anthropology graduate students offered enormous amounts of moral support and entertainment throughout my graduate career. Thank you for all of your help and the great times, Joyce Parga, Stacey Tecot, Katherine Whitcome, Magdalena Muchlinski, Carrie Veilleux, Michaela Nielson, Matt Kilberger, W. Andrew Barr, Amy Whitaker, Laurel Carnes, Carl Toborowsky, Amber Heard-Booth, Brett Nachman, Gabrielle Russo, Kat Bannar-Martin, Kelsey Ellis, Jaime Mata-Miguez, Rick Smith, Addie Kemp, Sierra Castedo, and Lina Valencia! Working with this wonderful group of students was one of the highlights of my time at UT. Thank you to M. Kilberger and C. Veilleux for helping found and maintain the (albeit short-lived) journal club, and to Claud Bramblett for all of his delightful discussions of each week’s vii article. To those who came before me, thank you for sharing your successful grant applications and for reading early versions of my own applications. I am especially thankful to K. Whitcome, A. Heard-Booth, and Nicole Griffin (Temple University) for their attentive discussions on lower limb mechanics. Most recently, I thank my postdoctoral advisor, Daniel Schmitt, and colleagues at the Duke University Animal Locomotion Lab. Thank you Daniel for defining heel-strike plantigrady and for sparking my initial interest in primate pedal mechanics. Thank you for taking the time to read every single word, for the engaging discussions on heel-strike mechanics, and for always bringing the enthusiasm even when mine was lacking. I appreciate how Daniel challenged me to think outside of my comfort zone and encouraged me to consider a whole different kettle of fish. I recognize Daniel as an honorary member of my dissertation committee. Sara Doyle, Roxy Larson, Karyne Rabey, and Charlotte Miller, you have all taught me many things, incuding the value of teaching, the importance of producing high quality research, and more gross anatomy than I ever imagined possible. Thank you, ladies, for all of your support. Additionally, I am especially grateful to Charlotte Miller and Christine Wall for statistical advice. Finally, I thank Roscoe Dick for being there during my many highs and lows. Thank you for being my partner in crime and for teaching me that there is so much more to life than just work. Thanks you for your patience, for picking me up when I was down, and for being the voice of reason every time I wanted to quit. I appreciate all of the many sacrifices that you had to make in order for me to achieve my goal and begin my postdoc. I couldn’t have finished without your moral support! This dissertation was funded by a National Science Foundation Doctoral Dissertation Impovement Grant (BCS 1028958) and the L.S.B. Leakey Foundation. viii Ontogeny of Bipedalism: Pedal Mechanics and Trabecular Bone Morphology Angel Diane Zeininger, Ph.D. The University of Texas at Austin, 2013 Supervisor: Liza Shapiro A unique pattern of pedal loading from heel-strike at touchdown to hallucal propulsion at toe-off is a distinct feature of mature human bipedalism, however, its first appearance in the fossil record is debated. The main goal of this dissertation is to identify anatomical correlates to a modern human heel-strike, rigid foot, and propulsive hallucal toe-off. First, a biomechanical analysis of toddler walking is used as a ‘natural experiment’ to investigate the influence of non heel-strike (NHS, n = 11) and immature heel-strike (IHS, n = 7) on the location of the center of pressure and orientation of the ground reaction force resultant in relation to specific foot bones during stance phase. With an expanded knowledge of foot bone loading in toddlers, a microarchitectural approach is used to test the influence of a heel-strike, rigid foot, and propulsive hallucal toe-off on trabecular bone fabric properties in an ontogenetic series of human and African ape (chimpanzee, bonobo, and gorilla) calcanei, tali, first metatarsal heads and hallucal distal phalanges. This dissertation presents the first ontogenetic analysis of pedal trabecular bone in primates.