Social and Behavioral Sciences Commons^™

Sexual Dimorphism In Titi Monkeys’ Digit (2d:4d) Ratio Is Associated With Maternal Urinary Sex Hormones During Pregnancy, Alexander Baxter, Elizabeth K. Wood, Lynea R. Witczak, Karen L. Bales, James Dee Higley

Faculty Publications

The second-to-fourth digit (2D:4D) ratio is a sexually-dimorphic biomarker for prenatal sex hormone exposure. We investigated whether titi monkeys (Plecturocebus cupreus) exhibit sexually-dimorphic 2D:4D ratio, and whether variation in 2D:4D ratio correlates with maternal testosterone and estrogen levels during early pregnancy. Subjects were 61 adult titi monkeys (32 males, 29 females). For 26 subjects, maternal urine samples were collected approximately 15–20 weeks before birth and assayed for testosterone and estrone conjugate (E1C). Titi monkeys exhibited a human-like pattern of sexual dimorphism in right-hand 2D:4D ratio, with females exhibiting higher 2D:4D ratio than males (β = −0.29, p = .023). For …