Finger Lengths & Androgen Receptor Polymorphism

Michael Scally MD

Doctor of Medicine
10+ Year Member
Breedlove SM. Minireview: Organizational Hypothesis: Instances of the Fingerpost. Endocrinology:en.2010-0041.

There is now compelling evidence that the ratio of the length of the second digit divided by the length of the fourth digit (2D:4D) is affected by prenatal androgens in humans. This ratio is greater in females than males from fetal life through adulthood, correlates with polymorphism in the androgen receptor gene in men, is feminine in XY androgen insensitivity syndrome, and masculinized in congenital adrenal hyperplasia. Using 2D:4D as a correlate, researchers have found evidence that prenatal androgens affect many sexually differentiated human behaviors, including sexual orientation in women (but not in men), attention deficit disorder, autism, eating disorders, aggression, and risk-taking. In each case, lower 2D:4D, indicative of greater prenatal androgen stimulation, is associated with behavior more commonly displayed by males than females. The correlation between 2D:4D and prenatal androgen stimulation is too imperfect to accurately predict the phenotype of a particular individual, even in terms of sex. However, digit ratio is the best available retrospective marker of average differences in prenatal androgen stimulation between groups of people, and/or correlations of prenatal androgen stimulation with particular behaviors and characteristics within a group. Thus digit ratios offer a valid test of the organizational hypothesis that androgens act early in life to masculinize various human behaviors.

What about the middle finger? LOL
 

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No, I think it means whenever that sick grandfather said to pull his finger, he was really spiking his test....[:o)] Thus denoted by the fart.....:D
 
BBC, u got it reversed...having a longer index finger correlates with LESS t exposure, not more.

anyway, it's interesting to see this 2d:4d theory mature, bcuz it's gone in a few contradictory directions...i happen to have somethinglike like a 93% 2d:4d ratio, so when the theory permuted to claim that such a ratio would ensure heterosexuality in males, i had to balk...since i'm gay cubed.

i wonder what further developments the theory will undergo...?
 
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