Doctoral Dissertation Improvement: Novel 3D analysis of hip joint mobility and the evolution of locomotor abilities in Miocene hominoids

博士候选人阿什利哈蒙德（密苏里-哥伦比亚大学）的研究，在卡罗尔沃德博士的监督下，将确定髋关节活动如何与运动行为和解剖形式在生活类人猿（猿和猴），以重建行为能力的化石猿从进化的关键中新世时期（约1990年）。23-5百万年前）。 树枝下悬挂行为使现代猿区别于大多数猴子，而类人猿运动行为的出现已经成为重建猿进化过程的决定性问题。 然而，众所周知，在化石猿中推断行为能力是很困难的，因为大多数化石猿显示出原始和现代解剖学的不寻常组合。 悬吊行为被假设为需要高髋关节活动性，提供了一种基于关节功能评估化石中悬吊能力的方法，但软组织对运动范围的影响必须在仅从化石骨骼重建关节运动之前进行表征。 本研究通过测量大样本活体（体内）猿和猴的被动运动范围，检验了悬吊类人猿的髋关节活动范围大于非悬吊类人猿的假设。 然后将从活体动物收集的测量结果与来自虚拟模型的运动范围估计进行统计学比较，虚拟模型依赖于骨骼解剖结构来限制关节运动。 验证模型的关节运动，然后用于评估髋关节活动性的解剖变异的影响，并适用于所有可用的化石猿，以确定他们是否适应使用悬挂行为。 这项研究建立了一种测试化石猿运动假说的方法，为人类起源的进化情景提供了关键数据。 这里开发的形状分析技术将是有用的所有脊椎动物形态学家，和验证的虚拟模型将作为一个比较模型，研究人员接近任何哺乳动物物种的关节功能。 更广泛地说，该项目将确定髋关节解剖形式的特定变化如何影响活动性，这可以集成到髋关节功能的临床模型中。 该项目为包括少数民族在内的本科生提供培训机会，并支持一名女博士生在一名女科学家的指导下进行研究。

Research by doctoral candidate Ashley Hammond (University of Missouri-Columbia), under the supervision of Dr. Carol Ward, will identify how hip joint mobility relates to locomotor behavior and anatomical form in living anthropoids (apes and monkeys) in order to reconstruct behavioral capabilities in fossil apes from the evolutionarily critical Miocene time period (ca. 23-5 million years ago). Below-branch suspensory behaviors distinguish modern apes from most monkeys, and the emergence of great ape-like locomotor behaviors has become the defining issue in reconstructing how apes evolved. Behavioral capabilities are notoriously difficult to infer in fossil apes, however, because most fossil apes display unusual combinations of primitive and modern anatomies. Suspensory behaviors are hypothesized to require high hip joint mobility, providing a method for evaluating suspensory abilities in fossils based on joint function, but the influence of soft tissues on range of motion must be characterized prior to reconstructing joint movement from just fossil bones. This study tests the hypothesis that suspensory anthropoids have larger ranges of hip mobility than non-suspensory anthropoids by measuring passive range of motion on a large sample of living (in vivo) apes and monkeys. The measures collected from live animals are then statistically compared to range of motion estimates from virtual models that rely on bony anatomy to limit joint movement. The validated model of joint movement is then used to assess the influence of anatomical variation on hip joint mobility and applied to all available fossil apes in order to identify whether they were adapted for using suspensory behaviors. This study establishes a method to test locomotor hypotheses in fossil apes, providing critical data for evolutionary scenarios of human origins. The shape analysis techniques developed here will be useful for all vertebrate morphologists, and the validated virtual models will serve as a comparative model for researchers to approach joint function in any mammalian species. More broadly, this project will identify how specific variation in hip joint anatomical form affects mobility, which can be integrated into clinical models of hip function. This project provides training opportunities for undergraduate students, including minorities, and is supporting the research of a female doctoral student being mentored by a female scientist.