Doctoral Dissertation Research: Evolutionary biomechanics of the human hyolingual apparatus

人类的舌头和舌骨因其在语言进化中的作用而被广泛研究。一些研究人员假设，我们独特的舌头和舌骨形态也使我们更容易窒息。这项研究使用先进的成像技术和计算建模来测试人类舌骨形态对吞咽是否有益。虽然这项研究的重点是在进化背景下的吞咽功能，但这项研究的结果也将促进我们对正常吞咽机制的理解，因此可能具有临床应用。该项目生成的计算模型软件将在完成后免费提供。该项目不仅为科学界的妇女提供指导研究，而且特别为学习生物力学的妇女提供指导研究，这是一个妇女人数不足的领域。此外，该项目将支持本科生研究和培训芝加哥大学的不同学生群体。人类的短脸和低舌，舌骨和喉被认为是适应讲话和不适应吞咽。最近的研究对这两种说法提出了质疑，促使人们进一步探索替代假说来解释人类独特的舌舌器官的起源。这个项目测试的假设，即舌骨生物力学约束形态，特别是低的舌骨装置是必要的，以保持吞咽性能，因为脸变得更短。运动形态X射线重建（XROMM）、基于扩散碘的对比增强CT（diceCT）和肌电图（EMG）将用于获得高时空分辨率的骨、舌和肌肉生物力学体内测量结果，包括灵长类动物模型系统中的舌舌肌长度、速度和活动。然后，这些数据将用于验证对吞咽生物力学和舌骨位置和颅面形态变化性能的影响的计算模型。证伪的约束假设将提供间接支持的假设，即人类声道的形态是自然选择的结果，言语性能。该项目将为未来的研究提供信息，以了解舌舌器的功能要求如何影响周围结构的形态，例如，下颌骨联合，在现存的和灭绝的分类群。

The human tongue and hyoid bone have been extensively studied for their role in the evolution of speech. Some researchers hypothesize that our unique tongue and hyoid morphology also makes us more prone to choking. This research uses advanced imaging techniques and computational modeling to test whether human hyolingual morphology is beneficial or detrimental for swallowing. While this research focuses on swallowing function in an evolutionary context, the findings of this research will also advance our understanding of normal swallowing mechanisms and therefore may have clinical applications. The software for the computational model generated by this project will be made freely available upon completion. This project provides mentored research not only to a woman in science but specifically one studying biomechanics, a field in which women are underrepresented. Furthermore, the project will support undergraduate research and training for a diverse group of students at the University of Chicago.The short faces and low tongue, hyoid, and larynx of humans have been argued to be adapted for speech and maladapted for swallowing. Recent studies cast doubt on both of these claims, prompting further exploration of alternative hypotheses to explain the origin of the uniquely human hyolingual apparatus. This project tests the hypothesis that hyolingual biomechanics constrain morphology, specifically that a low hyolingual apparatus is necessary to maintain swallowing performance as the face becomes shorter. X-ray Reconstruction of Moving Morphology (XROMM), diffusible iodine-based contrast-enhanced CT (diceCT), and electromyography (EMG) will be used to obtain high spatiotemporal resolution in vivo measurements of bone, tongue, and muscle biomechanics, including hyolingual muscle length, velocity, and activity in a primate model system. These data will then be used to validate a computational model of the impacts on swallowing biomechanics and performance of variation in hyolingual position, and craniofacial morphology. Falsification of the constraint hypothesis would provide indirect support for the hypothesis that the morphology of the human vocal tract is the result of natural selection for speech performance. This project will inform future research on how the functional requirements of the hyolingual apparatus may have influenced the morphology of surrounding structures, e.g., the mandibular symphysis, in both extant and extinct taxa.