July 5, 2011 -- The ratio between the length of the index finger and the ring finger of men's hands is associated with penis length, a study shows.

Researchers found that men with a lower ratio, or a shorter length of the index finger compared to the ring finger, tended to have a longer penile length.

The study is published in the Asian Journal of Andrology.

In earlier research, the ratio, known as the digit ratio, has been linked to sexual behavior or hormonal activity. A recent study linked digit ratio to facial attractiveness or "hotness," and another found an association between digit ratio and prostate cancer risk.

Those findings have prompted some to suggest that digit ratio may serve as a marker for prenatal androgen or testosterone exposure.

"Based on this evidence we suggest that the digit ratio can predict adult penile size and that the effects of prenatal testosterone may in part explain the differences in penile length," write study researcher In Ho Choi of Gachon University Hospital in Incheon, South Korea, and colleagues.