The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

First Molar Dental Fluctuating Asymmetry and the Pace of Life History in Non-Human Primates


Anthropology, The Ohio State University

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Fluctuating asymmetry (FA) occurs in morphological structures as small, random deviations from perfect bilateral symmetry without any directionality between sides. Extended periods of growth are argued to provide a ‘window of opportunity’ for growing body structures to accumulate deviations from perfect bilateral symmetry resulting in elevated FA. Utilizing the traditional continuum of slow-fast life history (LH) schedules as a proxy for developmental timing, this study examines if variation in primate first molar FA is associated with developmental timing. The following hypothesis is tested: species with slow LH schedules will exhibit elevated first molar FA relative to species with fast LH schedules. Using weaning age as an indicator of LH schedules, this study also tests if first molar FA is strongly correlated with weaning age.

Mesio-distal and bucco-lingual dimensions of maxillary and mandibular first molars of thirteen primate species were measured to calculate FA. The results support the hypothesis that species with prolonged LH schedules exhibit elevated FA relative to those species with shorter LH schedule. Great apes, who have slow LH schedules relative to other anthropoids, exhibit significantly greater first molar FA. Consistent with developmental differences in the dentition of frugivorous and folivorous species, the fast-growing folivore, Colubus guereza, expresses the lowest FA among Old World monkeys; however, not all comparisons are statistically significant. Finally, the correlation of first molar FA and weaning age is statistically significant. These results suggest that species with prolonged LH schedules are experiencing a greater number of developmental perturbations than species with fast LH schedules.

This research was supported by grants awarded to Sarah A. Martin from The Ohio State University Graduate School’s Alumni Grants for Graduate Research and Scholarship, Sigma Xi Chapter of Ohio State University, and the Wenner-Gren Foundation.

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