AN ANALYSIS OF MORPHOLOGICAL DIFFERENCES IN THE FEMORAL DIAPHYSEAL MIDSHAFT BETWEEN FOSSIL AND MODERN HUMANS A Thesis by BRITTANY LEIGH STAFF MOODY Submitted to the Office of Graduate and Professional Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF ARTS Chair of Committee, Sheela Athreya Committee Members, James Woolley David L. Carlson Head of Department, Cynthia Werner December 2017 Major Subject: Anthropology Copyright 2017 Brittany Leigh Staff Moody ABSTRACT The understanding of morphological variation between fossil and modern humans is critical to the discussion of evolutionary processes within the Homo lineage. Neanderthals are recognizably distinct in their morphology from Late Pleistocene Homo sapiens and recent modern humans, especially in the femoral midshaft cross-section. These lineages are often assumed to be independent when applying statistical methods to account for these morphological differences. The shared evolutionary history of fossil and modern humans, however, increases the likelihood that the distinction in observable traits cannot entirely be attributed to divergent selective pressures; morphological variation is obscured by phylogenetic signal and therefore violates assumptions of statistical independence. In order to understand the observed variation between these groups, phylogenetic signal must be taken into account. To test for phylogenetic signal in the femoral cross-section in recent human evolution, geometric morphometric shape data was taken from fossil groups (Neanderthals and Late Pleistocene Homo sapiens) and compared to a global recent modern human sample. This shape data was isolated from other morphological constraints through Procrustes superimposition and mapped onto a phylogeny created from mitochondrial genomes from geographic and temporally comparable populations. The trends in femoral midshaft cross-sectional shape variation were examined through Principal Component Analyses and Canonical Variate Analyses and showed concentrated shape change in the region of the pilaster. A permutation test indicated that phylogenetic signal is present in the femoral midshaft shape. The presence of this signal between fossil and modern human groups stresses the importance of taking into account, and controlling for, shared evolutionary history in comparative analyses. In order to understand the nature of the phylogenetic signal present in the femoral midshaft, independent contrasts were calculated and a multivariate regression was performed to test for the impact of evolutionary allometry. The results showed that allometric changes throughout modern and fossil human ii evolutionary history had an insignificant impact on changes in shape, explaining only 20% of shape variation. This, therefore, suggests that the observed shape changes at the femoral midshaft between these groups are not due to evolutionary allometry but can be attributed to other factors, such as behavioral, genetic, or environmental pressures. iii For Goldia. iv ACKNOWLEDGEMENTS I would like to express my deepest gratitude to all those people, personal and professional, who have helped me through all stages of the completion of this work. First and foremost, I am indebted to my committee chair and advisor, Dr. Sheela Athreya who has given so much of her time working with me on this project and to my development as a scholar. She has helped me in more ways that I can say through her support and mentorship, and has set forth the example of scholarship and excellence that I strive to emulate. I have grown academically and personally through my graduate experience, and I could not have done so without her. I am incredibly fortunate to be counted among her students. Additionally, I am extremely grateful to my committee members Dr. James Woolley and Dr. David Carlson without whom I could not have completed this project. I cannot express how much I have learned from them, nor how much their willingness to help me on any aspect of my thesis that I needed assistance with, including sitting down with me and working through specific aspects of my analyses, has helped me. Their feedback on my methods, interpretations, and communication of my research has helped make this work, and my own scholarship growth, possible. I would also like to thank Dr. Lori Wright for her guidance in both academic and personal matters, her advice and support have been invaluable to me throughout my graduate career. I cannot continue without acknowledging my heroes, my parents, Dr. George and Rene’ Staff. My father, George, has always shown me to do what I believe is right no matter what, and to have compassion for every living thing, no matter how small or seemingly insignificant. He has shown me that life and ambitions are worth fighting for regardless of the opinions of others or the difficulty of the dream. My mother, Rene’, has taught me that I have come from a long line of strong women and that strength is rooted in empathy, hard work, and love. She is the most remarkable woman I know, and teaches me how to be a better person every day through our conversations and by her v example. I am beyond fortunate to have parents who are also my closest friends and am unspeakably proud to be their daughter. I could not have been able to complete this work, or even begin my academic career, without the unyielding support of my husband and best friend, Ryan Moody. He has kept me grounded and been my sounding board throughout this process, making sure that I was taking care of myself as well as my goals and aspirations. He has made me a better person, through his example of patience, encouragement, and kindness; and a better scholar by reminding me to use what I have learned in all aspects of my life. He makes every day an adventure, and reminds me to find the joy in big and small things alike. I am forever grateful to share this life with him. vi CONTRIBUTORS AND FUNDING SOURCES Contributors This thesis was supported and supervised by a committee made up of Dr. Sheela Athreya, committee chair, from the Department of Anthropology as well as Dr. David Carlson, also from the Department of Anthropology, and Dr. James Woolley from the Department of Entomology. The raw femoral midshaft cross-sections outlined in Chapter IV (Materials), were supplied by Dr. Erik Trinkaus, Dr. Laura Shackelford, and Dr. Libby Cowgill. The mitochondrial DNA sequence for Pavlov 1 was supplied by Dr. Qiaomei Fu via personal communication. All other work performed for the thesis was completed by the student independently. Funding Sources No outside funding sources contributed to the research or the completion of this thesis. vii TABLE OF CONTENTS Page ABSTRACT……………………………………………………………………………... ii DEDICATION………………………………………………………………………….. iv ACKNOWLEDGEMENTS……………………………………………………………… v CONTRIBUTORS AND FUNDING SOURCES……………………………………… vii TABLE OF CONTENTS………………………………………………………………. vii LIST OF FIGURES………………………………………………………………......… xi LIST OF TABLES…………………………………………………………………….. xiii CHAPTER I. INTRODUCTION……………………………………………………………….. 1 II. POPULATION DIFFERENCES BETWEEN NEANDERTHALS AND LATE PLEISTOCENE HOMO SAPIENS WITH EMPAHSIS ON THE POSTCRANIA………………………………………………………… 5 Morphological Trajectories in Fossil Human Evolutionary History…………………………………………………………………… 6 Genetic Trajectories in Fossil Human Evolutionary History…………... 10 Postcrania Models on Femoral Morphology…………………………… 12 Cold Adaptation………………………………………………… 13 Postcranial Robusticity…………………………………………. 16 Bio-behavioral Factors…………………………………………. 18 Summary and Application……………………………………………… 19 III. CROSS-SECTIONAL FEMORAL MORPHOLOGY………………………… 21 Biomechanical Loading Patterns………………………………………. 22 Mobility Patterns and Activity Levels…………………………………. 24 Ontogenetic Factors……………………………………………………. 26 Terrain………………………………………………………………….. 27 Climatic Variation……………………………………………………… 28 Summary and Application……………………………………………… 28 IV. MATERIALS…………………………………………………………………... 30 Morphological Sample…………………………………………………. 30 Late Pleistocene Homo sapiens…………………………………...... 30 viii European Late Pleistocene Homo sapiens……………….. 30 West Asian Late Pleistocene Homo sapiens……………... 35 Neanderthals……………………………………………………. 37 European Neanderthals…………………………………. 37 Western Asian Neanderthals……………………………. 40 Recent Modern Humans………………………………………... 43 Alaskan Inuit……………………………………………. 43 Pre-Dynastic Egyptian………………………………….. 45 Libyan…………………………………………………... 45 Çatalhöyük……………………………………………… 45 Genetic Sample…………………………………………………………. 46 Late Pleistocene Homo sapiens…………………………………….. 47 Neanderthals……………………………………………………. 49 European Neanderthals…………………………………. 49 Western Asian Neanderthals…………………………… 50 Recent Modern Humans………………………………………... 51 V. METHODS……………………………………………………………………... 55 Morphological Data Collection………………………………………… 55 Phylogenetic Tree Model based on Mitochondrial DNA………………. 59 Digitizing Femoral Cross-Sections and Applying Landmarks…………. 63 Procrustes Transformation and Principal Component Analysis………... 67 Phylogenetic Signal for Shared Evolutionary History…………………. 68 VI. RESULTS………………………………………………………………………. 72 Procrustes Superimposition…………………………………………….. 72 Principal Components Analysis………………………………………… 75 Recent Modern Humans………………………………………... 75 Late Pleistocene Homo sapiens………………………................ 78 Neanderthals………………………...………………………...... 82 Combined Fossil Data………………………...………………… 91 Combined Modern and Fossil Human Data……………………. 94 Phylogenetic Signal Permutation Test……………………….................. 99 Evolutionary Allometry………………………...…………………......