Definitions
The development of human gender identity may be influenced by organizational effects of prenatal hormones. This includes physical and neural development. Digit ratio (or 2D:4D) is a proxy of fetal hormones that correlates negatively with prenatal testosterone and positively with prenatal estrogen. Studies investigating associations between 2D:4D and sex-dependent traits suggest that in addition to genetics, prenatal hormones contribute to the determination of gender.
Introduction
At birth, humans are typically assigned to their biological sex (male or female) on the basis of their genitalia. But there is evidence from fetal studies that the sexual differentiation of the body occurs before the sexual differentiation of the brain (Swaab 2007; Bao and Swaab 2011). This gives the opportunity for considerable plasticity with regard to the social roles that are considered...
This is a preview of subscription content, log in via an institution to check access.
References
Auyeung, B., Baron-Cohen, S., Ashwin, E., Knickmeyer, R., Taylor, K., Hackett, G., & Hines, M. (2009). Fetal testosterone predicts sexually differentiated childhood behavior in girls and in boys. Psychological Science, 20, 144–148.
Bao, A. M., & Swaab, D. F. (2011). Sexual differentiation of the human brain: Relation to gender identity, sexual orientation and neuropsychiatric disorders. Frontiers in Neuroendocrinology, 32, 214–226.
Baron-Cohen, S., Lutchmaya, S., & Knickmeyer, R. (2004). Prenatal testosterone in mind. Cambridge, MA: MIT Press.
Bem, S. L. (1981). Gender schema theory: A cognitive account of sex typing. Psychological Review, 88, 354–364.
Berta, P., Hawkins, J. R., Sinclair, A. H., Taylor, A., Griffiths, B. L., Goodfellow, P. N., & Fellous, M. (1990). Genetic evidence equating SRY and the testis-determining factor. Nature, 348, 448–450.
Eagly, A. H. (1997). Sex differences in social behavior: Comparing social role theory and evolutionary psychology. American Psychologist, 52, 1380–1383.
Heylens, G., De Cuypere, G., Zucker, K. J., Schelfaut, C., Elaut, E., Vanden Bosche, H., et al. (2012). Gender identity disorder in twins: A review of the case report literature. The Journal of Sexual Medicine, 9, 751–757.
Hofstede, G. (1991). Cultures and organizations: Software of the mind. New York: McGraw-Hill.
Leinung, M. D., & Wu, C. (2017). The biologic basis of transgender identity: 2D:4D finger length ratios implicate a role for prenatal androgen activity. Endocrine Practice, 23, 669–671.
Lippa, R. (1998). Gender-related individual differences and the structure of vocational interests: The importance of the people-things dimension. Journal of Personality and Social Psychology, 74, 996–1009.
Lutchmaya, S., Baron-Cohen, S., & Raggatt, P. (2002). Foetal testosterone and eye contact in 12-month-old human infants. Infant Behavior & Development, 25, 327–335.
Manning, J. T. (2002). Digit ratio: A pointer to fertility, behavior and health. New Brunswick: Rutgers University Press.
Manning, J. T., & Fink, B. (2011). Digit ratio (2D:4D) and aggregate personality scores across nations: Data from the BBC internet study. Personality and Individual Differences, 51, 387–391.
Manning, J. T., Baron-Cohen, S., Wheelwright, S., & Sanders, G. (2001). The 2nd to 4th digit ratio and autism. Developmental Medicine and Child Neurology, 43, 160–164.
Manning, J. T., Stewart, A., Bundred, P. E., & Trivers, R. L. (2004). Sex and ethnic differences in 2nd to 4th digit ratio in children. Early Human Development, 80, 161–168.
Manning, J. T., Reimers, S., Baron-Cohen, S., Wheelwright, S., & Fink, B. (2010). Sexually dimorphic traits (digit ratio, body height, systemizing–empathizing scores) and gender segregation between occupations: Evidence from the BBC internet study. Personality and Individual Differences, 49, 511–515.
Manning, J. T., Fink, B., & Trivers, R. (2014). Digit ratio (2D:4D) and gender inequalities across nations. Evolutionary Psychology, 12, 757–768.
Manning, J. T., Trivers, R., & Fink, B. (2017). Is digit ratio (2D:4D) related to masculinity and femininity? Evidence from the BBC internet study. Evolutionary Psychological Science. https://doi.org/10.1007/s40806-017-0098-4.
Martel, M. M., Gobrogge, K. L., Breedlove, S. M., & Nigg, J. T. (2008). Masculinized finger-length ratios of boys, but not girls, are associated with attention-deficit/hyperactivity disorder. Behavioral Neuroscience, 122, 273–281.
McCarthy, M. M., Auger, A. P., Bale, T. L., De Vries, G. J., Dunn, G. A., Forger, N. G., et al. (2009). The epigenetics of sex differences in the brain. Journal of Neuroscience, 29, 12815–12823.
Pauly, I. B. (1998). Gender identity and sexual orientation. In D. Denny (Ed.), Current concepts in transgender identity. New York: Garland Publishers.
Qian, W., Huo, Z., Lu, H., Sheng, Y., Geng, Z., & Ma, Z. (2016). Digit ratio (2D:4D) in a Chinese population with schizophrenia. Early Human Development, 98, 45–48.
Reimers, S. (2007). The BBC internet study: General methodology. Archives of Sexual Behavior, 36, 147–161.
Saenz, J., & Alexander, G. M. (2013). Digit ratios (2D:4D), postnatal testosterone and eye contact in toddlers. Biological Psychology, 94, 106–108.
Saraswat, A., Weinand, J. D., & Safer, J. D. (2015). Evidence supporting the biologic nature of gender identity. Endocrine Practice, 21, 199–203.
Schneider, H. J., Pickel, J., & Stalla, G. K. (2006). Typical female 2nd-4th finger length (2D:4D) ratios in male-to-female transsexuals-possible implications for prenatal androgen exposure. Psychoneuroendocrinology, 31, 265–269.
Swaab, D. F. (2004). The human hypothalamus. Basic and clinical aspects. Part II: Neuropathology of the hypothalamus and adjacent brain structures. In M. J. Aminoff, F. Boller, & D. F. Swaab (Eds.), Handbook of clinical neurology. Amsterdam: Elsevier.
Swaab, D. F. (2007). Sexual differentiation of the brain and behavior. Best Practice & Research. Clinical Endocrinology & Metabolism, 21, 431–444.
Swaab, D. F., & Garcia-Falgueras, A. (2009). Sexual differentiation of the human brain in relation to gender identity and sexual orientation. Functional Neurology, 24, 17–28.
Szwed, A., Kosinska, M., & Manning, J. T. (2017). Digit ratio (2D:4D) and month of birth: A link to the solstitial-melatonin-testosterone effect. Early Human Development, 104, 23–26.
Wallien, M. S. C., Zucker, K. J., Steensma, T. D., & Cohen-Kettenis, P. T. (2008). 2D:4D finger-length ratios in children and adults with gender identity disorder. Hormones and Behavior, 54, 450–454.
Acknowledgments
Robert Trivers thanks the Enhanced Learning Foundation and the Biosocial Research Foundation for their support. Bernhard Fink is currently funded by the German Science Foundation, grant no. FI1450/7-2.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Section Editor information
Rights and permissions
Copyright information
© 2018 Springer International Publishing AG
About this entry
Cite this entry
Manning, J.T., Fink, B., Trivers, R. (2018). Biology of Human Gender, The. In: Shackelford, T., Weekes-Shackelford, V. (eds) Encyclopedia of Evolutionary Psychological Science. Springer, Cham. https://doi.org/10.1007/978-3-319-16999-6_3827-1
Download citation
DOI: https://doi.org/10.1007/978-3-319-16999-6_3827-1
Received:
Accepted:
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-16999-6
Online ISBN: 978-3-319-16999-6
eBook Packages: Springer Reference Behavioral Science and PsychologyReference Module Humanities and Social SciencesReference Module Business, Economics and Social Sciences