Digit Ratio: An Indicator to the World Within

The ratio of index finger length to ring finger length known as digit ratio (2D:4D) is an indicator of prenatal androgen exposure. The 2D:4D ratio is sexually dimorphic, with average male 2D:4D lesser than average female 2D:4D. It recently was suggested that 2D:4D is negatively correlated with prenatal testosterone and positively correlated with prenatal estrogen. It is argued that high prenatal testosterone and low estrogen (indicated by low 2D:4D) favours the male foetus and low prenatal testosterone and high estrogen (indicated by high 2D:4D) favours the female foetus. According to a broad array of studies, this ratio, determined by the level of prenatal testosterone, can predict a diversity of personality traits. In part icular, individuals whose index finger is almost as long-or even longer-than is their ring finger are more likely to display characteristics that are characteristic of females. Even their writing tends to be more feminine in style. But usually, not always, these observations apply to the right hand only. Even within each sex, 2D:4D has been found to be linked with a variety of physical and psychological characteristics. For example, men with lower 2D:4D are more aggressive, more athletic, less feminine, and more musically talented. Women with lower 2D:4D have higher waist-to-hip ratio, are more masculine, and are more athletic. Among both men and women, 2D:4D is correlated positively with verbal intelligence and agreeableness, and negatively with numerical intelligence and physical fitness. The present paper aims at establishing the relationship between various physical and psychological aspects of personality and digit ratio through a review of existing literature.