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Archives of Sexual Behavior

, Volume 35, Issue 6, pp 739–742 | Cite as

Population Differences in Finger-Length Ratios: Ethnicity or Latitude?

  • John C. Loehlin
  • Dennis McFadden
  • Sarah E. Medland
  • Nicholas G. Martin
Article

The relative length of the second and fourth fingers (the 2D:4D ratio) has been taken to be an indicator of prenatal exposure to testosterone, and hence possibly relevant to sexual orientation and other sex-differentiated behaviors. Studies have reported a difference in this ratio between Caucasian males in Britain and in the U.S.: higher average 2D:4D ratios were obtained in Britain. This raises the question of whether differences among different Caucasian gene pools were responsible or whether some environmental variable associated with latitude might be involved (e.g., exposure to sunlight or different day-length patterns). This question was explored by examining 2D:4D ratios for an Australian adolescent sample. The Australians were predominantly of British ancestry, but lived at distances from the equator more like those of the U.S. studies. The Australian 2D:4D ratios resembled those in Britain rather than those in the U.S., tending to exclude hypotheses related to latitude and making differences in gene pools a plausible explanation.

Key Words

2D:4D ratio finger lengths masculinization ancestry latitude 

Notes

ACKNOWLEDGMENTS

We are grateful to Ann Eldridge, Marlene Grace, Narelle Hansell, and David Smyth for assistance with the Australian data.

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Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • John C. Loehlin
    • 1
    • 3
  • Dennis McFadden
    • 1
  • Sarah E. Medland
    • 2
  • Nicholas G. Martin
    • 2
  1. 1.Department of PsychologyUniversity of TexasAustinUSA
  2. 2.Queensland Institute of Medical ResearchBrisbaneAustralia
  3. 3.Department of PsychologyUniversity of TexasAustinUSA

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