Abstract
Prenatal androgen exposure has important organising effects on brain development and influences future behavioural patterns. Second to fourth digit ratio (2D:4D) is a marker for prenatal androgen exposure and as such is a sexually dimorphic trait. Smaller, more masculine second digit (index finger) to fourth digit (ring finger) ratio’s are associated with higher exposure to prenatal testosterone levels or greater sensitivity to androgens, or both. People with smaller finger ratios, a longer fourth finger than second finger, have been shown to be more successful in competitive sports, exhibit increased visuo-spatial ability, more fertile and are perceived as being more masculine and dominant by female observers. Smaller ratios have also been associated with an increased propensity to engage in aggressive behaviour. We examined the relationship between Boxer’s fractures, a traditional injury of aggression and finger length ratio.
We reviewed 1123 patient records and/or hand x rays over a seven month time frame showing 123 fifth metacarpal (Boxer’s) fractures. We then measured, using recorded radiological data, the distance in millimetres from the base of the proximal phalanx to the tip of the distal phalanx for the second, third and fourth fingers. We also recorded sex, side of injury, site of injury and mode of injury.
One hundred and twenty three Boxer’s fractures were found over a seven month time period, 110 male and 13 female; 67.27% were right sided. The average age was 27.6 yrs ±14.2. The average finger length ratio (proximal phalanx to distal phalanx) for males was 0.9 and for females was 0.94. Both ratios were smaller than the published normal digit ratio for the general population.
Smaller second digit to fourth digit ratios are positively associated with persons presenting with fifth metacarpal fractures, thereby indicating increased aggressive tendancies independently of gender
The abstracts were prepared by Mr Matt Costa and Mr Ben Ollivere. Correspondence should be addressed to Mr Costa at Clinical Sciences Research Institute, University of Warwick, Clifford Bridge Road, Coventry CV2 2DX, UK.
