Finger length ratio

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A small 2D: 4D correlates with a relatively high fetal testosterone level.

Finger length ratio describes the ratio of the length of the index finger to the length of the ring finger and is therefore also called 2D: 4D (D for digitus, Latin for finger / toe). The finger length ratio correlates with the ratio of fetal estradiol to fetal testosterone level .

Correlative studies show an association between finger length ratio and fetal growth, handedness , autism , Asperger's syndrome , sperm count , family size , age at heart attack in men and breast cancer in women. It could also be shown that alcohol addiction and dependent video games are associated with a smaller 2D: 4D finger length ratio. A questionnaire study with 134 Austrian professional firefighters stated: "The more masculine the expression of the finger length ratio, [...] the more the firefighter generally strives for risky behavior".

Since a high natural testosterone level is a biomarker of athletic performance and talent in strength / speed strength sports, such individuals are systematically searched for. Most recently it was tennis where it was identified as a talent criterion.

distribution

A visualization of the distribution: men (blue), women (green) and the whole population (red), based on a study by the University of Alberta

From a study of 136 men and 137 women at the University of Alberta :

  • Men: mean 0.947, standard deviation 0.029
  • Women: mean 0.965, standard deviation 0.026

Assuming a normal distribution, this leads to 95% prediction intervals for the 2D: 4D ratio of 0.889–1.005 for men and 0.913–1.017 for women.

From a 2018 study of 249 PhD and undergraduate students from Warwick University, proportionally balanced by gender:

  • Men: mean 0.951, standard deviation 0.035
  • Women: mean 0.968, standard deviation 0.028

literature

  • John T. Manning: Digit ratio: a pointer to fertility, behavior, and health. Rutgers University Press, 2002, ISBN 0-8135-3030-X .

Individual evidence

  1. ↑ S. Lutchmaya, S. Baron-Cohen, P. Raggatt, R. Knickmeyer, JT Manning: 2nd to 4th digit ratios, fetal testosterone and estradiol. In: Early Human Development. 77, 2004, pp. 23-28, doi: 10.1016 / j.earlhumdev.2003.12.002 .
  2. ↑ Johannes Kornhuber, Gabriele Erhard u. a .: Low Digit Ratio 2D∶4D in Alcohol Dependent Patients. In: PLoS ONE. 6, 2011, p. E19332, doi: 10.1371 / journal.pone.0019332 .
  3. ↑ Johannes Kornhuber, Eva-Maria Zenses u. a .: Low 2D: 4D Values ​​Are Associated with Video Game Addiction. In: PLoS ONE. 8, 2013, p. E79539, doi: 10.1371 / journal.pone.0079539 .
  4. ↑ Ulrike Pum: Test theoretical analysis of the Sensation Seeking scale V and connections with relationship quality, professional commitment and digit ratio (2D: 4D) in firefighters . (PDF) Diploma thesis, October 2008, p. 98 ,; accessed on December 12, 2017
  5. ^ Arnd Krüger : finger length. In: competitive sport (magazine) 41 (2011), 2, pp. 38–39.
  6. ↑ CC Hsu, B. Su, NW Kan, SL Lai, TH Fong, CP Chi, CC Chang, MC Hsu: Elite collegiate tennis athletes have lower 2D: 4D ratios than those of nonathlete controls. In: Journal of strength and conditioning research. Volume 29, number 3, March 2015, pp. 822-825, doi: 10.1519 / JSC.0000000000000681 , PMID 25226321 .
  7. ↑ livescience.com: Finger Length Predicts Aggression in Men
  8. ↑ frontiersin.org: Self-confidence, Overconfidence and Prenatal Testosterone Exposure: Evidence from the Lab