Archives of Sexual Behavior

, Volume 36, Issue 2, pp 223–233

The Effects of Sex, Ethnicity, and Sexual Orientation on Self-Measured Digit Ratio (2D:4D)

  • John T. Manning
  • Andrew J. G. Churchill
  • Michael Peters
Original Paper

Abstract

We used self-reported direct finger measurements from 255,116 participants in a BBC Internet survey to investigate the measurement of 2D:4D ratios and their association with sex, ethnicity, and sexual orientation. We found significant sex differences such that males had lower 2D:4D than females and the effect size of the sex differences was greatest for right hand 2D:4D. Mean 2D:4D was lower for right hands than for left hands in men, but lower for left hands compared to right hands in women. The sexual dimorphism in 2D:4D was present across ethnic and country groupings, suggesting that it is universal in humans. However, there was also evidence that mean 2D:4D varied across ethnic groups with higher ratios for Whites, Non-Chinese Asians, and Mid-Easterners and lower ratios in Chinese and Black samples. There were significant differences in 2D:4D across sexual orientation groups but these were confined to men. Male homosexuals and bisexuals had higher mean 2D:4D (suggesting exposure to lower prenatal T) than heterosexuals. The effect was present in Whites, but there was no evidence for the pattern among Black and Chinese participants. In women, there were no significant effects of sexual orientation on 2D:4D. Most studies of sexual orientation effects on 2D:4D have measured finger length from photocopies of the hands. In comparison, our self-reported measures gave higher mean 2D:4D, lower effect sizes, and, in some instances, different patterns of effect size. The implications of our findings for future research into 2D:4D are discussed.

Keywords

Sex Sexual orientation Digit ratio 2D:4D 

References

  1. Breedlove, S. M., Cooke, B. M., & Jordan, C. L. (1999). The orthodox view of brain sexual differentiation. Brain, Behavior and Evolution, 54, 8–14.PubMedCrossRefGoogle Scholar
  2. Brown, W. M., Finn, C. J., & Breedlove, S. M. (2002). Sexual dimorphism in digit-length ratios of laboratory mice. Anatomical Record, 267, 231–234.PubMedCrossRefGoogle Scholar
  3. Brown, W. M., Finn, C. J., Cooke, B. M., & Breedlove, S. M. (2002). Differences in finger length ratios between self-identified “butch” and “femme” lesbians. Archives of Sexual Behavior, 31, 123–127.PubMedCrossRefGoogle Scholar
  4. Brown, W. M., Hines, M., Fane, B. A., & Breedlove, S. M. (2002). Masculinized finger length patterns in human males and females with congenital adrenal hyperplasia. Hormones and Behavior, 42, 380–386.PubMedCrossRefGoogle Scholar
  5. Buck, J. J., Williams, R. M., Hughes, I. A., & Acerini, C. L. (2003). In-utero androgen exposure and 2nd to 4th digit length ratio–comparisons between healthy controls and females with classical congenital adrenal hyperplasia. Human Reproduction, 18, 976–979.PubMedCrossRefGoogle Scholar
  6. Burley, N. T., & Foster, V. S. (2004). Digit ratio varies with sex, egg order and strength of mate preference in zebra finches. Proceedings of the Royal Society of London B, 271, 239–244.Google Scholar
  7. Burriss, R. P., Little, A. C., & Nelson, E. C. (in press). 2D:4D and sexually dimorphic facial characteristics. Archives of Sexual Behavior.Google Scholar
  8. Caswell, N., & Manning, J. T. (in press). Self-reported direct measurements of the fingers yield higher digit ratios (2D:4D) than experimenter-measured photocopied fingers. Archives of Sexual Behavior.Google Scholar
  9. Cattrall, F. R., Vollenhoven, B. J., & Weston, G. C. (2005). Anatomical evidence for in utero androgen exposure in women with polycystic ovary syndrome. Fertility and Sterility, 84, 1689–1692.PubMedCrossRefGoogle Scholar
  10. Fink, B., Thanzami, V., Seydel, H., & Manning, J. T. (2006). Digit ratio and hand-grip strength in German and Mizos men: Cross-cultural evidence for an organizing effect of prenatal testosterone on strength. American Journal of Human Biology, 18, 776–782.PubMedCrossRefGoogle Scholar
  11. Hall, L. S., & Love, C. T. (2003). Finger-length ratios in female monozygotic twins discordant for sexual orientation. Archives of Sexual Behavior, 32, 23–28.PubMedCrossRefGoogle Scholar
  12. Kallai, J., Csatho, A., Kover, F., Makany, T., Nemes, J., Horvath, K., et al. (2005). MRI-assessed volume of left and right hippocampi in females correlates with the relative length of the second and fourth fingers (the 2D:4D ratio). Psychiatry Research: Neuroimaging, 140, 199–210.Google Scholar
  13. Kondo, T., Zakany, J., Innis, J., & Duboule, D. (1997). Of fingers, toes and penises. Nature, 390, 29.PubMedCrossRefGoogle Scholar
  14. Leoni, B., Canova, L., & Saino, N. (2005). Sexual dimorphism in metapodial and phalanges length ratios in the wood mouse. Anatomical Record, 286, 955–961.PubMedGoogle Scholar
  15. Lippa, R. A. (2003). Are finger-length ratios related to sexual orientation? Yes for men, no for women. Journal of Personality and Social Psychology, 85, 179–188.PubMedCrossRefGoogle Scholar
  16. Lutchmaya, S., Baron-Cohen, S., Raggatt, P., Knickmeyer, R., & Manning, J. T. (2004). 2nd to 4th digit ratios, foetal testosterone and estradiol. Early Human Development, 77, 23–28.PubMedCrossRefGoogle Scholar
  17. Malas, M. A., Dogan, S., Hilal Evcil, E., & Desdicioglu, K. (in press). Fetal development of the hand, digits and digit ratio (2D:4D). Early Human Development.Google Scholar
  18. Manning, J. T. (2002). Digit ratio: A pointer to fertility, behavior, and health. New Brunswick, NJ: Rutgers University Press.Google Scholar
  19. Manning, J. T., Bundred, P. E., Newton, D. J., & Flanagan, B. F. (2003). The second to fourth digit ratio and variation in the androgen receptor gene. Evolution and Human Behavior, 24, 399–405.CrossRefGoogle Scholar
  20. Manning, J. T., Callow, M., & Bundred, P. E. (2003). Finger and toe ratios in humans and mice: Implications for the aetiology of diseases influenced by HOX genes. Medical Hypotheses, 60, 340–343.PubMedCrossRefGoogle Scholar
  21. Manning, J. T., Fink, B., Neave, N., & Caswell, N. (2005). Photocopies yield lower digit ratios (2D:4D) than direct finger measurements. Archives of Sexual Behavior, 34, 329–333.PubMedCrossRefGoogle Scholar
  22. Manning, J. T., & Robinson, S. J. (2003). 2nd to 4th digit ratio and a universal mean for prenatal testosterone in homosexual men. Medical Hypotheses, 61, 303–306.PubMedCrossRefGoogle Scholar
  23. Manning, J. T., Scutt, D., Wilson, J., & Lewis-Jones, D. I. (1998). The ratio of 2nd to 4th digit length: A predictor of sperm numbers and concentrations of testosterone, luteinising hormone and oestrogen. Human Reproduction, 13, 3000–3004.PubMedCrossRefGoogle Scholar
  24. Manning, J. T., Stewart, A., Bundred, P. E., & Trivers, R. L. (2004). Sex and ethnic differences in 2nd to 4th digit ratio of children. Early Human Development, 80, 161–168.PubMedCrossRefGoogle Scholar
  25. McFadden, D., Loehlin, J. C., Breedlove, S. M., Lippa, R. A., Manning, J. T., & Rahman, Q. (2005). A reanalysis of five studies on sexual orientation and the relative length of the 2nd and 4th fingers (the 2D:4D ratio). Archives of Sexual Behavior, 34, 341–356.PubMedCrossRefGoogle Scholar
  26. McFadden, D., & Shubel, E. (2002). Relative lengths of fingers and toes in human males and females. Hormones and Behavior, 42, 492–500.PubMedCrossRefGoogle Scholar
  27. McIntyre, M. H., Ellison, P. T., Lieberman, D. E., Demerath, E., & Towne, B. (2005). The development of sex differences in digital formula from infancy in the Fels Longitudinal study. Proceedings of the Royal Society of London B, 272, 1473–1479.Google Scholar
  28. McMechan, A. P., O’Leary-Moore, S. K., Morrison, S. D., & Hannigan, J. H. (2004). Effects of prenatal alcohol exposure on forepaw digit length and digit ratios in rats. Developmental Psychobiology, 45, 251–258.PubMedCrossRefGoogle Scholar
  29. Migeon, C. J., & Wisniewski, A. B. (1998). Sexual differentiation: From genes to gender. Hormone Research, 50, 254–251.CrossRefGoogle Scholar
  30. Okten, A., Kalyonku, M., & Yaris, N. (2002). The ratio of second-and fourth digit lengths and congenital adrenal hyperplasia due to 21-hyroxylase deficiency. Early Human Development, 70, 47–54.PubMedCrossRefGoogle Scholar
  31. Peters, M., Mackenzie, K., & Bryden, P. (2002). Finger length and distal finger extent patterns in humans. American Journal of Physical Anthropology, 117, 209–217.PubMedCrossRefGoogle Scholar
  32. Rahman, Q. (2005). Fluctuating asymmetry, second to fourth finger length ratios and human sexual orientation. Psychoneuroendocrinology, 30, 382–391.PubMedCrossRefGoogle Scholar
  33. Rahman, Q., & Wilson, G. D. (2003). Sexual orientation and the 2nd to 4th finger length ratio: Evidence for organizing effects of sex hormones or developmental instability? Psychoneuroendocrinology, 28, 288–303.PubMedCrossRefGoogle Scholar
  34. Reimers, S. (2007). The BBC internet study: General methodology. Archives of Sexual Behavior, 36, doi: 10.1007/s10508-006-9143-2.Google Scholar
  35. Rizwan, S., Manning, J. T., & Brabin, B. J. (2007). Maternal smoking during pregnancy and possible effects of in utero testosterone: Evidence from the 2D:4D finger length ratio. Early Human Development, 83, 87–90.Google Scholar
  36. Robinson, S. J., & Manning, J. T. (2000). The ratio of 2nd to 4th digit length and male homosexuality. Evolution and Human Behavior, 21, 333–345.PubMedCrossRefGoogle Scholar
  37. Romano, M., Rubolini, D., Martinelli, R., Alquati, A. B., & Saino, N. (2005). Experimental manipulation of yolk testosterone affects digit length ratios in the ring-necked pheasant (Phasianus colchicus). Hormones and Behavior, 48, 342–346.PubMedCrossRefGoogle Scholar
  38. Roney, J. R., Whitham, J. C., Leoni, M., Bellem, A., Wielebnowski, N., & Maestripieri, D. (2004). Relative digit lengths and testosterone levels in Guinea baboons. Hormones and Behavior, 45, 285–290.PubMedCrossRefGoogle Scholar
  39. Rubolini, D., Pupin, F., Sacchi, R., Gentilli, A., Zuffi, M. A., Galeotti, P., et al. (2006). Sexual dimorphism in digit length ratios in two lizard species. Anatomical Record, 288, 491–497.PubMedGoogle Scholar
  40. Saino, N., Rubolini, D., Romano, M., & Boncoraglio, G. (2007). Increased egg estradiol concentration feminizes digit ratios in male pheasants. Naturwissenschaften, 94, 207–212.Google Scholar
  41. Tortorice, J. L. (2002). Written on the body: Butch /femme lesbian gender identity and biological correlates. Unpublished doctoral dissertation, Rutgers University.Google Scholar
  42. Trivers, R., Manning, J., & Jacobson, A. (2006). A longitudinal study of digit ratio (2D:4D) and other finger ratios in Jamaican children. Hormones and Behavior, 49, 150–156.PubMedCrossRefGoogle Scholar
  43. van Anders, S. M., Vernon, S. M., & Wilbur, C. J. (2006). Finger length ratios show evidence of prenatal hormone transfer between opposite-sex twins. Hormones and Behavior, 49, 315–319.PubMedCrossRefGoogle Scholar
  44. Voracek, M., Manning, J. T., & Ponocny, I. (2005). Digit ratio (2D:4D) in homosexual and heterosexual men from Austria. Archives of Sexual Behavior, 34, 335–340.PubMedCrossRefGoogle Scholar
  45. Wallen, K. (2005). Hormonal influences on sexually differentiated behavior in nonhuman primates. Frontiers in Neuroendocrinology, 26, 7–26.PubMedCrossRefGoogle Scholar
  46. Williams, T. J., Pepitone, M. E., Christensen, S. E., Cooke, B. M., Huberman, A. D., Breedlove, N. J., et al. (2000). Finger-length ratios and sexual orientation. Nature, 404, 455–456.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • John T. Manning
    • 1
  • Andrew J. G. Churchill
    • 1
  • Michael Peters
    • 2
  1. 1.Department of PsychologyUniversity of Central LancashirePrestonUK
  2. 2.Department of PsychologyUniversity of GuelphGuelphCanada

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