(INCHEON, South Korea) -- The longer a man's index finger when compared with his ring finger, the longer the length of his penis, according to Korean researchers.
The research team, led by urologist Dr. Tae Beom Kim from Gachon University in Incheon, Korea, measured the fingers and penises -- both stretched-out and flaccid -- of 144 men who were anesthetized before undergoing urological surgery.
Men's ring fingers are usually longer than their index fingers. But Kim and colleagues linked a larger gap in finger length -- a lower 2D:4D ratio -- to a longer stretched-out penis.
"Based on this evidence, we suggest that digit ratio can predict adult penile size, and that the effects of prenatal testosterone may in part explain the differences in adult penile length," the researchers reported Monday in the Asian Journal of Andrology.
The length of the penis when stretched is believed to correlate to its erect length, the team reported.
Earlier studies suggest the 2D:4D ratio is governed by prenatal exposure to the male and female sex hormones, testosterone and estrogen. Women tend to have ring and index fingers of roughly equal length -- a result of less testosterone exposure in the womb, report the Korean researchers.
But men who have relatively long ring fingers are thought to have been exposed to high levels of testosterone in utero, and this has been linked to aggression, athleticism, sexuality, intelligence, and even the ability to trade high-stakes stocks. It has also been linked to a higher risk for amyotrophic lateral sclerosis, or Lou Gehrig's disease, prostate cancer and arthritis.
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