title: An endocrine basis for tomboy identity: The second-to-fourth digit ratio (2D:4D) in "tomboys".
abstract: This paper investigates the relationship between organizational effects of pre-natal testosterone and the use of "tomboy" as a descriptor for young women. We show in a sample of 44 women that a woman's right hand 2D:4D ratio is a significant predictor of whether they will be labeled as a "tomboy", with a decrease in 2D:4D ratio corresponding to an increase in the probability of being called "tomboy". Taking the right hand 2D:4D ratio as a proxy for the abundance of testosterone in the early life hormonal milieu, we propose that organizing effects of higher pre-natal T lead to increased masculine-typical behavior in childhood, which increases the likelihood some women will be referred to as tomboys. We suggest that the increase in masculine-typical behaviors is a result of how the organizing effects of T on the brain interact with children's social modeling of male-coded and female-coded behaviors.
authors.affiliation: Centre for Behaviour and Evolution, Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK. Electronic address: bethatkinson1008@gmail.com.
authors.forename: Beth M
authors.initials: BM
authors.lastname: Atkinson
authors.affiliation: Centre for Behaviour and Evolution, Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK. Electronic address: tom.smulders@ncl.ac.uk.
authors.forename: Tom V
authors.initials: TV
authors.lastname: Smulders
authors.affiliation: Centre for Behaviour and Evolution, Institute of Neuroscience, Newcastle University, Newcastle Upon Tyne NE2 4HH, UK; School of English Literature, Language and Linguistics, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK. Electronic address: joel.wallenberg@ncl.ac.uk.
authors.forename: Joel C
authors.initials: JC
authors.lastname: Wallenberg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000886:Anthropometry; D005260:Female; D005385:Fingers / Q000033:anatomy & histology*; D005783:Gender Identity; D006801:Humans; D008875:Middle Aged; D055815:Young Adult
keywords: 2D:4D; Gender; Neuroendocrinology; Testosterone; Tomboys