Abstract # 13141 Poster # 91:

Scheduled for Thursday, August 9, 2018 06:00 PM-08:00 PM: (Chula Vista ) Poster Presentation


SEXUAL DIMORPHISM IN 2D:4D RATIO IS ASSOCIATED WITH MATERNAL URINARY SEX HORMONES IN A REPRESENTATIVE NEW WORLD MONKEY (CALICEBUS CUPREUS)

 

A. Baxter1, E. K. Wood1, L. R. Witczak2,3, K. L. Bales2,3 and J. D. Higley1
1Brigham Young University, 1001 SWKT, Provo, UT 84602, USA, 2University of California, Davis, 3California National Primate Research Center
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Across human (Homo sapiens) and nonhuman primates, the second-to-fourth digit (2D:4D) ratio is sexually dimorphic, and a validated, proxy measure of prenatal sex hormone exposure. While many primate species show sex differences in this trait, it is unknown whether New World (NW) monkeys exhibit sexual dimorphism in 2D:4D ratio. In this study, we investigate 2D:4D ratio in a representative NW species, coppery titi monkeys (Callicebus cupreus), and whether variation in 2D:4D ratio correlates with maternal urinary testosterone and estrogen concentrations during gestation. Subjects were 60 adult titi monkeys housed at California National Primate Research Center. For n=30 subjects, maternal testosterone and estrogen concentrations were assayed from urine samples (3-8 per subject) collected approximately 15-20 weeks before birth. Data showed that titi monkeys exhibit a human-like pattern of sexual dimorphism in right-hand 2D:4D (R2D:4D) ratio, with females exhibiting higher R2D:4D ratio than males (t-test, t(58) = 2.46, p=.017). Further analyses showed that for females, high levels of maternal estrogen were associated with low (male-typical) left-hand 2D:4D (L2D:4D) ratio (general linear model (GLM), β = -.68, p<.001). For both sexes, high maternal estrogen-to-testosterone ratios were associated with low L2D:4D ratio (GLM, β = -.49, p<.001). This is the first report of a sex difference in 2D:4D ratio in a NW species, and results suggest that 2D:4D ratio is a complex biomarker for prenatal sex hormone exposure.