Prenatal Androgen Exposure is Associated with Sex Role Iden9ty and Physical Preferences in Poten9al Mates Among Straight Males Ben Dalecki, Gordon Andrews, and Michael J. Brown State University of New York – College at Oneonta Abstract
This study examines the rela1onship between the 2D:
4D ra1o (a crude biological marker of prenatal androgen exposure), gender role iden1ty, and physical preferences in poten1al mates among straight par1cipants. One hundred and thirty-­‐two (33% male and 67% female) undergraduate students served as par1cipants in this analysis. Among male par1cipants, higher (more “feminine”) 2D:4D ra1os on the right hand were associated with more “feminine” sex role iden11es, a greater preference for “masculine” physical traits in poten1al mates, and greater sexual aLrac1on to the same sex. There were no significant correla1ons between these variables and 2D:4D ra1os among female par1cipants. Our results suggest that prenatal androgen exposure is related to sex role iden1ty and sexual aLrac1on in straight males, but not straight females. Background
Research suggests that the rela1ve length of the 2nd and 4th digits (2D:4D ra1o) may be a useful indicator of prenatal androgen exposure. Differences in rela1ve finger length are sexually dimorphic, in that males have lower mean 2D:4D ra1os than females. This phenomenon is present in newborns and shows liLle or no change at puberty (Manning, Churchhill, & Peters, 2007), sugges1ng that prenatal hormone exposure is responsible. Furthermore, a study that examined radio-­‐immunoassays of fetal testosterone and estradiol obtained from aminocentesis of fetuses showed a nega1ve rela1onship between the testosterone/estradiol ra1o and the 2D:4D ra1o measured when the children were 2 years old (Lutchmaya, Baron-­‐Cohen, RaggaL, Knickmeyer, & Manning, 2004). A number of studies have found significant differences in 2D:4D ra1os between heterosexual and homosexual men and women. Williams et. al. (2000) found that the 2D:4D ra1o in lesbians was significantly more masculine (smaller) than that of straight females. Lippa (2003) found a significant difference in finger-­‐length ra1os between gay and straight males: Straight males had significantly smaller 2D:4D ra1os (d = -­‐.32). The purpose of this study was to examine if prenatal androgen exposure, as measured by the 2D:4D ra1o, is related to straight individuals’ sex role iden1ty and physical preferences in poten1al mates. Results
Among male par1cipants, higher (more “feminine”) 2D:
4D ra1os on the right hand (but not the lej) were associated with more “feminine” sex role iden11es (r = .
32, p < .05), a greater preference for “masculine” physical traits in poten1al mates (r = .41, p < .05), and greater sexual aLrac1on to the same sex (r = -­‐.22, p = .05). There were no significant correla1ons between these variables and 2D:4D ra1os among female par1cipants. Discussion
Method
Par$cipants One hundred and thirty-­‐two (33% male and 67% female) undergraduate students served as par1cipants in this study. All par1cipants in this analysis self-­‐iden1fied as “straight”. The mean age of par1cipants was 21.8 (SD = 4.77) and ranged from 18 to 51. The sample was racially diverse: White = 43%; Black = 11%; Hispanic = 27%; Asian = 9%; 10% other. Design and Procedures As part of a larger study on the 2D:4D ra1o and crea1ve ability, par1cipants completed the Bem Sex Role Inventory (Bem, 1981), a 6-­‐item sexual orienta1on scale (Kinsey, Pomeroy, & Mar1n, 1948), a modified version of the Body Parts Sa1sfac1on Scale (Berscheid, Hadield, & Bohnstedt, 1972) to measure physical preferences in mates, and a socio-­‐demographic ques1onnaire. Par1cipants also provided a high-­‐resolu1on, full-­‐size digital scan (using a Canoscan N670U scanner) of both of their hands. These scans were printed full-­‐size on 8.5” x 11” paper and measured by two research assistants who calculated the finger length ra1o for the 2nd and 4th digits using an 8” frac1onal caliper with digital LCD display (Calpri, Model #CP20002). The inter-­‐rater reliability of the measurements was high: 96%. The mean of the two measurements was used in this analysis. Our results suggest that prenatal androgen exposure is related to sex role iden1ty and sexual aLrac1on in straight males, but not straight females. The rela1vely low number of male par1cipants (n = 37) raises concerns about generalizability and sta1s1cal power. The study should be replicated with a larger sample size. We are in the process of collec1ng data on the rela1onships between the 2D:4D ra1on, sexual orienta1on, and crea1vity. References
Lippa, R. A. (2003). Are 2D:4D finger-­‐length ra1os related to sexual orienta1on? Yes for men, no for women. Journal of Personality and Social Psychology, 85(1), 22-­‐35. Lutchmaya, S., Baron-­‐Cohen, S., Ragget, P., Knickmeyer, R., & Manning, J. T. (2004). 2nd to 4th digit ra1os, female testosterone and estradiol. Early Human Development. 77(1-­‐2), 23-­‐28. Manning, J.T., Churchill, A. J. G., Peters, M. (2007). The effects of sex, ethnicity, and sexual orienta1on on self-­‐
measured digit ra1o (2D:4D). Archives of Sexual Behavior, 36(2), 223-­‐233.