Doctoral Dissertation Research: The evolution of human balance

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During hominin evolution, the transition to upright posture and bipedal locomotion was associated with many anatomical changes. This doctoral dissertation research project examines an understudied aspect of inner ear anatomy that contributes to our sense of balance during movement. The investigator compares aspects of inner ear anatomy for humans, primates, and fossil hominins, and examines its relationship with head and neck posture and cranial anatomy. Results from this project advance our understanding of how anatomical structures associated with balance changed with the transition to bipedalism during hominin evolution and may allow for better reconstructions of postural behavior from fossil specimens. The project also contributes to medical treatment by providing insights into the potential for vestibular dysregulation in humans and creating a quantifiable and reproducible visualization of vestibular anatomy that aids precise surgical targeting and development of vestibular prostheses. During the course of the project the investigator will incorporate 3D printed models, illustrations, and animations of the results into public outreach programs in New York City designed to teach human evolutionary concepts to the public. These include programs at the American Museum of Natural History; undergraduate courses at Lehman College; and an undergraduate seminar on the use of multimedia and interactive design in science education.The vestibular system consists of the semicircular canals (detecting angular acceleration) and the otolith organs (detecting linear acceleration and head tilt relative to gravity) housed within the bony vestibule of the inner ear. In contrast to considerable study of the semicircular canals in primates, the comparative functional morphology of the otolith organs is largely unknown. This knowledge gap has limited our understanding of the evolution of primate, and more specifically human, head and neck posture (head positioning and range of motion). This project uses both Micro-Computed Tomography and Synchrotron Resonance Phase Contrast Imaging to create a morphometric model of the encasing bony morphology (bony vestibule) specific to otolith organ geometry in order to investigate the evolution and functional morphology of the bony vestibule in humans, primates, and fossil hominins. The investigator examines modern human bony vestibule variation and function, consider correlations between bony vestibule morphology and head position and anatomy in a comparative primate sample, and compare modern human and reconstructed fossil hominin bony vestibule features. The research clarifies how the vestibular system and head and neck posture changed alongside one another throughout human evolution and allow future study into the way(s) bony vestibule morphology is correlated with extant primate and reconstructed hominin postural behaviors.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.