In Utero Androgen Exposure & Aggression

Abstract

Various research studies have indicated a smaller second (2D) to fourth digit (4D) ratio in males compared to females. Testosterone levels have been determined in utero by observation of the length of the fourth digit, whereas length of the second digit can be discovered by the volume of oestrogen found in the placenta and foetal ovaries in females. Several sources have indicated the 2D: 4D ratio being connected to aggressive traits in the population. Aim: To determine whether there is a relationship between aggressive behaviour as assessed by the Buss-Perry questionnaire and in utero testosterone exposure using measurements of 2D: 4D ratio as a surrogate marker. Methodology: Measurements of 2D: 4D ratios were taken from 34 healthy individuals using electronic callipers on both left and right hands. The participants were then given questions, regarding age, sex, dominant hand, participation in competitive sports, and were additionally asked to complete the Buss-Perry questionnaire. Results: Males had higher 2D: 4D ratios (1.01±0.04) and aggression scores (79.23±14.15) than females (1.00±0.04 and 69.29±18.93 respectively). There was no correlation between overall 2D: 4D and aggression, this was proved after using a Pearsons correlation test (r = 0.20 and p>0.05). Conclusions: Aggression scores were higher in males than females. Males were found to have higher second to fourth digit ratios however, no significance was found between 2D: 4D ratio and aggression. Key Words: Aggression, In Utero, 2D: 4D Ratio, Testosterone, Androgen Exposure, and Behaviour