Type
Text
Type
Dissertation
Advisor
Jungers, William L. | Grine, Frederick E. | O'Higgins, Paul. | Baab, Karen L.
Date
2017-08-01
Keywords
Physical anthropology | Chimpanzee | Evolution (Biology) | Craniofacial | Cranium | Geometric morphometrics | Modern humans | Morphological integration
Department
Department of Anthropology.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree
Identifier
http://hdl.handle.net/11401/78355
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Modern humans have flatter faces, wider palates and smaller teeth compared to chimpanzees and our early human ancestors. Many hypotheses concerning the evolution of the human face assume a relationship between the face and the teeth. It is likely that the face and teeth develop in a coordinated manner throughout the growth and development of an organism due to similar developmental origins, and functions, and the teeth residing in the maxillae. What is not fully understood is whether the face and teeth are two separate units (modules) that can evolve independently or if they are tightly correlated (integrated) during evolution. This dissertation analyzed the pattern and magnitude of morphological integration between the face and the teeth in humans and chimpanzees to test whether specific changes in the size and shape of the lower face during growth are associated with particular dental developmental events, such as the formation or eruption of the permanent molars. Computed tomography scans were used to generate 3D surfaces of the crania and dentition of chimpanzees and humans. The size and shape of the specimens were quantified with 3D landmarks, multivariate geometric morphometric analyses and traditional linear measurements. Specimens were divided into four dental stages based on permanent molar eruption to assess size and shape changes throughout ontogeny. The lower face and permanent dentition are integrated in humans and chimpanzees in adults and throughout ontogeny. A relatively more prognathic lower face, and a taller, narrower and longer palate are associated with more protruding and larger anterior teeth. Individuals with relatively broader midfaces, shorter palates, and less prognathic lower faces have more retracted, smaller and shorter anterior teeth. The magnitudes of integration are similar at equivalent dental stages of humans and chimpanzees, but the degree of integration declined during dental stages with mixed deciduous and permanent dentition. The face and teeth comprise one module, but shape covariation was primarily demonstrated between the face and the incisors and canines, and not the molars. This suggests some modularity between the incisors and molars that would allow the independent evolution of a flatter face and smaller anterior dentition even as molars increase in size. | 188 pages
Recommended Citation
Nesbitt, Allison, "Morphological Integration between the Face and Dentition throughout Ontogeny" (2017). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 3849.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/3849