As there are a lot of fingers, I will concentrate on the length of the index finger (the one next to the thumb) relative to the ring finger, as men have an index finger shorter than the ring finger. However, the relative lengths of these two fingers vary within each sex, and remarkably these differences are associated with some characteristics of human sexual behavior.
Index Finger longer than Ring Finger?
Some physiologists say that men with longer index fingers exhibit more jealousy towards rivals, whereas men with shorter index fingers are more aggressive towards male competitors and have much younger women as partners. They also have higher sperm numbers, are married to women with the longest index fingers, and produce more children. How can this be?
Length of Fingers
The variability in finger length seems to be due to exposure of the fetus to differing levels of the male hormone testosterone. For example, some fetuses have tissues insensitive to testosterone and so grow relatively longer index fingers whereas others produce excessive amounts of the hormone and so have smaller index fingers. Girls from non-identical boy/girl twin pairs have shorter index fingers than non-identical twins where both are girls. Higher testosterone in the womb produces more masculine characteristics in the adult.
Even more intriguingly, other aspects of human behavior, such as competitiveness, are associated with the relative length of these two fingers. Professional footballers have relatively shorter index fingers compared to non-professionals, first-team players have shorter index fingers than reserve players, and international players have the shortest index fingers. As the length of this finger is associated with certain aspects of human reproduction, it’s clear that professional footballers can do much more than bending it like Beckham.