The relationship between 2D:4D ratio and aggression among individuals participating in contact sports.

Background: Connections have been made between the relative lengths of the index and ring fingers, known as the 2D:4D ratio, to prenatal testosterone exposure. The lower the digit ratio presents in adulthood should indicate that an individual was subjected to a higher concentration of testosterone while in the womb. Furthermore increased testosterone has also been linked to an increase in aggression, so it has been hypothesised that more aggressive individuals should have smaller 2D:4D ratios. It has been suggested that individuals who participate in more aggressive forms of sports such as those with a certain level of contact intensity, should display a higher level of aggression generally. Therefore it is expected that participants of contact sports should not only demonstrate higher aggression levels, but also possess lower 2D:4D ratios to signify this. Aim: To determine whether the 2D:4D ratio indicates heightened aggression levels in students participating in contact sports Methodology: Electronic callipers were used to measure the second and fourth digits from both hands of 44 volunteers, split equally among those who did or did not participate in a contact sport. Participants were then asked to fill in a Buss Perry (1992) aggression questionnaire. Results: There was no significant differences observed between either the 2D:4D ratios (contact: 1.00±0.03mm; non-contact: 0.99±0.03mm; p=0.44) or the aggression levels (contact: 77.05±21.86; non-contact: 71.45±16.24; p=0.35) between the contact and non-contact groups. There was also no significant correlation between the 2D:4D ratio and aggression when groups were considered separately (contact: r=-0.04, p=0.85; non-contact: r=-0.06, p=0.80) nor together (r=-0.03, p=0.842). Significance was taken as p