Presenter: Kelsey Clarke
Mentors: Stephen Frost and Frances White, Anthropology
Poster: 12
Major: Anthropology
Fluctuating Asymmetry (FA) has been hypothesized to be related to testosterone levels and mating strategies; typically males are more asymmetrical than females. Second-to-fourth digit ratio (2D:4D) is correlated with developmental testosterone levels. Using 2D:4D and cranial FA from 19 primates, we compare the relationship between these variables to their respective mating systems. Forty-five landmarks were digitized using a Microscribe- 3DX© for 345 male and 307 female crania. Cranial FA was measured by calculating the Procrustes’ distance between each individual and its mirror-image. Mating systems, classified by intensity and frequency of male aggression, and sex-specific 2D:4D were taken from published studies. Cranial FA and 2D:4D were compared using parametric correlation. Two-way ANOVA of sex and species with a priori multiple comparisons between mating systems was used to examine variation in individual FA. Cranial FA and 2D:4D were correlated (r=-0.460,P<0.05). Cranial FA significantly differed among species (F=64.84,N=19,P<0.05), but there was no difference between sexes (F=1.08,ns) and no sex-species interaction (F=1.24,ns). Multiple comparisons grouping species by mating systems within this ANOVA showed significant differences between pair-bonded and non-pair bonded (F=30.79,P<0.05), between low intensity and high intensity (F=136.76,P<0.05) within non-pair bonded, and between low frequency and high frequency (F=154.62,P<0.05) within high intensity and non-pair bonded. These results support the hypothesis that cranial FA is correlated with testosterone and the variance in male aggression among mating systems.