This study proposes to apply advanced engineering methods to study primate hip function. The primate hip joint is a complex structure that serves a wide range of purposes. A better understanding of this structure will not only facilitate our knowledge of hip joint function but also provide important evidence about the evolutionary process of early human locomotion. This is because the hip joint underwent substantial reorganization in the transition to a bipedal form of locomotion. Despite extensive research efforts devoted to this structure in the last two centuries, hip functions remain poorly understood. Up until now, most work has been confined to the documentation of the shape of the hip skeleton and little effort has been invested to analyze the functional implications of observed morphological traits. This project will take a comprehensive approach that has only recently become possible. It will for the first time systematically incorporate external hip morphology, internal trabecular bone density patterns, and functional loads into global femoral and acetabular models. It will examine the relationship between form and function in the hip of humans as well as various other large bodied primates. The objectives of this study are: (1) To quantify bone density patterns in behaviorally diverse monkeys, apes, and humans. (2) To test predictions concerning the biomechanical significance of isolated joint features. (3) To integrate external morphological features, internal architecture and joint loads into a single global model so that the relative sensitivity of single variables and sets of variables to joint forces and muscle forces can be investigated. (4) To use those variables which are found to be sound indicators of loading to reconstruct positional behavior in fossil species. This project will make substantial contributions in the following fields: (1) Comparative Functional Morphology: This study will contribute new information to the field of comparative anatomy by integrating data on joint surface geometry, trabecular bone density and mechanical loading. (2) Paleoanthropology: This study will extend our current understanding of form/function relationships in the hip of living primates and provide paleontologists with new tools to reconstruct positional behavior in extinct species. (3) Methodological Contribution: The integration of modern bone remodeling theories with computer and bioengineering technologies is a new approach in biological anthropology and will help to establish new research frontiers.
