Evaluation of Craniofacial Superimposition As a Technique for Measuring Mountain Gorilla Facial Soft Tissue Depth and Implications for Hominid Facial Approximation
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Evaluation of Craniofacial Superimposition as a Technique for Measuring Mountain Gorilla Facial Soft Tissue Depth and Implications for Hominid Facial Approximation by Marli Richmond B.A. in Anthropology, May 2015, East Carolina University A Thesis submitted to The Faculty of The Columbian College of Arts and Sciences of The George Washington University in partial fulfillment of the requirements for the degree of Master of Arts May 20, 2018 Thesis directed by Shannon McFarlin Associate Professor of Anthropology Acknowledgments I express my sincerest appreciation for my advisor, Shannon McFarlin, for her guidance, patience, and encouragement of my research and development as a graduate student and anthropologist. My gratitude goes to the Mountain Gorilla Skeletal project, for curating the research sample used in this study, and Jason Massey for his tremendous effort in making the skeletal material used in this research available for study. The MGSP collection is supported by funding from the National Science Foundation (BCS-0852866, BCS- 0964944, BCS-1520221), National Geographic Society’s Committee for Research and Exploration (8486-08), and The Leakey Foundation as well as the Rwanda Development Board’s Department of Tourism and Conservation, Dian Fossey Gorilla Fund International, Gorilla Doctors, The George Washington University, New York University College of Dentistry, Institute of National Museums of Rwanda, and other universities in Rwanda and the U.S.A. I am extremely grateful to Jordi Galbany for his time and work collecting gorilla tissue thickness measurements in the field, and to the Gorilla Doctors for making these data available. I am indebted to the staff of Dian Fossey Gorilla Fund International’s Karisoke Research center, who work tirelessly toward the observation and protection of mountain gorillas, and the preservation of their skeletal remains. I would like to thank the Rwandan government and national parks authorities for permission to work in Volcanoes National Park, as well as access to mountain gorilla skeletal data for research. I gratefully acknowledge the contributions of field assistants, students, researchers and other staff of ii the Rwanda Development Board-Department of Tourism and Conservation, Mountain Gorilla Veterinary Project, the National University of Rwanda, the Higher Institute of Agriculture and Animal Husbandry in Rwanda, the Institute of National Museums of Rwanda, and academic institutions of the U.S.A. This project would not have been possible without the long term datasets, and field and infrastructural support of these organizations. I gratefully acknowledge Marilyn London for her helpful feedback and support of my development as an anthropologist. A special thanks is extended to Melinda Richmond for her time, patience and analytical expertise. I would like acknowledge the generosity of faculty and students, at The George Washington University’s Center for the Advanced Study of Human Paleobiology, for their support and feedback. Lastly, I owe my gratitude to the Gorillas at Karisoke Research Center, who made this research possible. iii Abstract of Thesis Evaluation of Craniofacial Superimposition as a Technique for Measuring Mountain Gorilla Facial Soft Tissue Depth and Implications for Hominid Facial Approximation Paleoanthropological facial approximation (also known as hominid facial reconstruction) refers to the results and investigations undertaken to determine and represent the life appearance of the earliest humans. Integrating skeletal, biomechanical, behavioral and environmental data, each approximation takes us on a journey through time, embodies decades of research and archaeological discovery, and tells the unique story of a species in anatomic detail. Despite its utility in connecting scientific and public audiences, facial approximation remains hindered by two factors: the first, a lack of methodological standardization and testing within the field, and the second a lack of facial thickness data for non-human primates. This study presents a novel application of craniofacial superimposition as a noninvasive way to measure facial soft tissue depth in great apes. Three-dimensional skull models and corresponding ante-mortem images of six adult male mountain gorillas (Gorilla beringei beringei) are overlaid in a computer-automated superimposition, and the point-to-point distances between skull surfaces and outer facial envelopes measured. A series of statistical analyses assess variation in measurements due to the type of software and number of images used. Further comparisons are drawn between mountain gorillas, chimpanzees, and humans in facial tissue thickness. Results support craniofacial superimposition as a measurement approach. However further study is needed to determine the technical limits that may occur in practice and improve methods for use in facial approximation and paleoanthropology. iv Table of Contents Acknowledgments ..............................................................................................................ii Abstract of Thesis...............................................................................................................iv List of Figures ...................................................................................................................vii List of Tables ...................................................................................................................viii Chapter 1: Introduction .......................................................................................................1 1.1 The Utility of Primate Facial Soft Tissue Depth...............................................1 1.2 Research Questions ...........................................................................................2 Chapter 2: Literature Review ..............................................................................................4 2.1 Traditional Facial Approximation......................................................................4 2.2 Facial Soft Tissue Depth: A Turning Point in the Field....................................5 2.3 Facial Approximation in Paleoanthropology ....................................................7 2.4 Craniofacial Superimposition..........................................................................10 Chapter 3: Methods and Materials ....................................................................................13 3.1 Materials..........................................................................................................13 3.2 Superimposition Procedure..............................................................................16 3.3 Statistical Analysis ..........................................................................................21 Chapter 4: Results .............................................................................................................23 4.1 Assessment of CFS-based FSTD values .........................................................23 4.2 Interspecific FSTD Comparison .....................................................................34 Chapter 5: Discussion and Conclusions ............................................................................37 5.1 Discussion .......................................................................................................37 5.2 Project Limitations ..........................................................................................37 v 5.3 Project Contributions and Opportunities for Future Work .............................39 References .........................................................................................................................41 Appendices ........................................................................................................................47 Needle Puncture Protocol..................................................................................................47 vi List of Figures Figure 1, Map indicating location of Volcanoes National Park..................................................13 Figure 2, Frontal and lateral views of soft tissue depth landmark measurement sites on gorilla skull..........................................................................................20 Figure 3, Mean FSTDs (mm) at each landmark obtained through Cephalometrics© CFS by those obtained with Maxilim® CFS.................................................28 Figure 4, Bar graph displaying CFS-based mean FSTD values at single craniofacial landmark (Glabella) to illustrate difference in measurements between Cephalometrics© and Maxilim®.........................................................29 Figure 5, Plot comparing mean FSTD values collected directly from chimpanzee, human, and mountain gorilla ..............................................................................35 vii List of Tables Table 1, List of Individuals included in study (sales aged 18-27) ....................................14 Table 2, Craniofacial landmark measurement sites used in study with descriptions.........19 Table 3, CFS-based FSTD means (mm) per three measurement trials using Cephalometrics©...............................................................................................................23 Table 4, CFS-based FSTD means (mm) per three measurement trials using Maxilim®...........................................................................................................................23 Table 5, Per-point FSTD measurements