Guys with shorter index fingers than ring fingers tend to have bigger penises than guys with the opposite digit scenario, finds a new study in the Asian Journal of Andrology.
Men who came in to a Korean hospital for urological surgery were anesthetized, scientists measured consenting patients’ penises.
Fact: Since shorter members stretch more than longer ones, the stretched measurement—used by the researchers—is more telling about the size of an erect penis. Other researchers measured the patients’ index and ring fingers.
The connection: The testosterone men get exposed to while they’re still fetuses controls both penis and finger length, the researchers explain.
The early testosterone exposure causes a shorter index finger than ring fingers—known as a low digit ratio. These men tend to have a higher risk of prostate cancer, be better at sports and financial trading, and have higher sperm counts.
The study says that the average size of an erect penis is about 5.5 inches.