Doctoral Dissertation Improvement: 3-D Modeling of in vivo Bite Force Production and Efficiency in Recent Humans as a Baseline for Evolutionary Change in Homo

在国家科学基金会的支持下，该项目将对活人面部形态和咬合力产生之间的关系进行详细分析，为未来尼安德特人面部形态的研究奠定基础。面部骨骼的形状受到各种因素的影响，既有遗传因素，也有环境因素。影响面部骨骼的最重要的环境因素之一是咀嚼力量的产生(例如，咬合力)。虽然咀嚼生物力学在面部发育中的重要性在进化和临床环境中都得到了认可，但这些变量之间的确切关系仍然很少被理解。理解这种关系对于尼安德特人的脸部很重要，因为高强度咬合力的产生和消散被用作解释尼安德特人面部解剖的进化发展的工作模型，尼安德特人的面部解剖与现代人的面部形态有很大不同。对尼安德特人咬合力的产生进行适当的评估是不可能的，因为咬合力的产生是骨骼和肌肉组织相互作用的结果，而肌肉组织没有保存在化石中。因此，以前对尼安德特人咀嚼性能的分析仅限于数学模型，其准确性还没有得到很好的证实。考虑到这些局限性，研究人员必须转向不仅提供骨骼和软组织数据，还提供实际咬合力测量的生物模型。该项目的目标有两个。首先，研究人员将在活人样本中检查咬合力产生和面部形态之间的关系，以确定面部骨骼的大小和形状是否与实际咬合力测量相关。这将通过爱荷华大学人类学系以及爱荷华大学医院和诊所的耳鼻喉科和放射科的共同努力来实现。将从招募的受试者中测量咬合力，并将其与受试者的CT扫描获得的骨骼和肌肉数据进行比较。其次，这个项目的数据将被用来验证一个定制编写的计算机程序，该程序仅基于骨骼变量对咬合力产生进行数学模拟。通过使用受试者CT扫描的骨骼数据，研究人员将对他们的咬合力产生进行数学估计，并将这些结果与实际值进行比较。一旦得到验证，该程序将成为未来研究的宝贵工具，准确估计尼安德特人的咬合力产量。人类学和临床对面部解剖和咬合力的研究历来是相互独立的。这是不幸的，因为这两个领域都有相辅相成的独特视角。因此，这项研究的更广泛影响是，它将把这两个在操作上截然不同的研究领域结合在一起。这样，在进化框架中提出的问题可以帮助完善和改进临床颅面治疗，而从研究活人中获得的临床知识可以丰富对我们人类祖先化石的颅面生物学的解释和重建。

With National Science Foundation support, this project will provide a detailed analysis of the relationship between facial form and bite force production in living humans to establish a baseline for future studies of Neandertal facial form. The form of the facial skeleton is influenced by a variety of factors, both genetic and environmental. One of the most important environmental factors affecting the facial skeleton is the production of masticatory forces (e.g., bite force). While the importance of masticatory biomechanics in facial development is recognized in both evolutionary and clinical contexts, the exact nature of the relationship between these variables is still poorly understood. Understanding this relationship is important with respect to the Neandertal face as the production and dissipation of high magnitude bite forces has been used as a working model to explain the evolutionary development of Neandertal facial anatomy which differs substantially from the facial form of living people. A proper assessment of Neandertal bite force production has not been possible since bite force production results from an interaction of both skeletal and muscle tissue, and the latter is not preserved in fossils. Therefore, previous analyses of Neandertal masticatory performance have been restricted solely to mathematical modeling, the accuracy of which is has not been well established. Given these limitations, researchers must turn to a living model that provides not only bone and soft tissue data but also actual bite force measurements.The objectives of this project are twofold. First, the investigators will examine the relationship between bite force production and facial morphology in a living human sample to determine if the size and shape of the facial skeleton correlate with actual bite force measurements. This will be accomplished through a joint effort of the Department of Anthropology at The University of Iowa along with the Departments of Otolaryngology and Radiology at The University of Iowa's Hospitals and Clinics. Bite force measures will be taken from recruited subjects and compared to skeletal and muscle data taken from CT scans of the subjects. Second, the data from this project will be used to validate a custom written computer program that mathematically models bite force production based solely on skeletal variables. By using skeletal data from the subjects' CT scans, the investigators will produce mathematical estimates of their bite force production and compare these results to actual values. When validated, this program will then serve as an invaluable tool for future studies that will accurately estimate Neandertal bite force production. Anthropological and clinical studies of facial anatomy and bite force have historically operated independently of one another. This is unfortunate given that both fields have unique perspectives that complement one another. Thus the broader impacts of this study are that it will marry these two operationally distinct research areas. In this way, questions posed in an evolutionary framework can help refine and improve clinical craniofacial treatment, while the clinical knowledge gained in studying living humans can enrich the interpretation and reconstruction of the craniofacial biology of our fossil human ancestors.