Functional adaptation of mandibular trabecular bone and its association with diet: Inter- and intra-specific comparisons among Homo sapiens, papionins, and mice.
University of Cambridge
Doctor of Philosophy (PhD)
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Brown, E. (2021). Functional adaptation of mandibular trabecular bone and its association with diet: Inter- and intra-specific comparisons among Homo sapiens, papionins, and mice. (Doctoral thesis). https://doi.org/10.17863/CAM.85525
Mandibular cortical bone morphology varies considerably across mammals and has been attributed to changes in feeding behaviour related to diet, subsistence and food mechanical properties (FMPs), including the shift from hunter-gathering to agriculture within humans during the Neolithic. Trabecular bone is the internal structure that resides within most bones in the mammalian skeleton, and it also varies in response to differing levels of strain according to the Bone Functional Adaptation theory. Trabecular bone has been analysed in a variety of contexts in the post-cranial skeleton and the primate mandible in relation to both locomotor functions and FMPs. However, there is little research into trabecular bone diversity in relation to intraspecific variation of masticatory function. Understanding how trabecular bone differs in response to dietary variation in human and non-human primate groups can be used to improve interpretations of evolutionary and temporal variation of diet in the past. Furthermore, comparisons of trabecular morphology of mice in a controlled experimental model allows for validation of any observations evidenced in the humans and non-human primates and effects of extrasomatic processing of food in humans. This thesis investigates, a) whether variation in diet corresponds with trabecular bone morphology in the mandible among closely related groups of the same species; and b) how this variation differs between each of these species. This research uses three-dimensional volumetric analyses to quantify the trabecular bone across a sample of 9 human, 5 macaque, 3 baboon and 2 mouse groups with documented dietary differences, which represent a number of diverse ecologies and locomotor behaviours. Data was collected via μCT scanning at the Cambridge Biotomography centre and the London Natural History Museum. Trabecular bone was analysed via BoneJ and consisted of three volumes of interest (VOI) from the condyle in humans and cercopithecoids, and one from the corpus in mice. Statistical analysis consisted of a combination of tests, including ANOVA, Kruskal-Wallis, Mantel, Principal Component Analyses, Multiple Multivariate Regression, and General Linear Models to determine any intra- and inter-species variation. Results illustrated significant variation amongst trabecular parameters that corresponded with differences in diet among humans and mice, however, limited differences were seen between the baboons and macaques. Significant differences were found between both human and macaque groups that could not be explained by dietary variation, suggesting strong influences from phylogenetics, as well as effects from ontogeny and sex in mice. Similarities between mice and humans suggest there are significant impacts on trabecular bone variation due to extrasomatic processing of food. These data illustrate that multiple factors may influence trabecular morphology in the mandible, which may or may not be consistent with known genetic relationships among taxa. In addition, distinctions were found between the different VOIs of the mandibular condyle that differed between human groups from the same subsistence strategy, suggesting that paramasticatory behaviour, or influences from health and nutrition, likely impact trabecular morphology. This research demonstrates that trabecular morphology in the mandibular condyle and corpus may be used to interpret behaviour relating to mastication and diet across humans, non-human primates and mice.
Trabecular bone, Diet, Mandible, Bioarchaeology, MicroCT
AHRC, Isaac Newton Trust
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This record's DOI: https://doi.org/10.17863/CAM.85525
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