Your hands can reveal a great deal about you. But for men, they can also indicate the size of their testicles, according to a study.
Researchers from South Korea worked out that with a man's right hand, the length of the index finger compared to the ring finger correlate with "testicular volume", while factors such as age or height do not.
In the study of 172 Koreans aged between 20 and 69, they found men who had a ring finger longer than their index finger had larger testicles, while those with an index finger that was longer than their ring finger had smaller testicles.
The researchers from the Department of Urology at Gachon University Gil Hospital and Seoul National University Hospital measured the length of the second and fourth digits of each participant who had been hospitalised for urological surgery. Then a urologist measured the size of their testicles.
At the end of the trial, it was concluded: "Age, height, serum testosterone and free testosterone level were not correlated with testicular volume, while digit ratio, along with weight, were significantly correlated with testicular volume."
Previous research also found a correlation between the second and fourth digit ratio and male fertility. It is based on the finding that finger and genital development are under the control of Hox genes during the embryonic stage.
It has also been proven the difference between the lengths of the two fingers is bigger in men than in women.