The digit ratio, specifically the length of the ring and index fingers, is linked to physical and psychological traits. It is a result of hormone exposure in the womb and varies among ethnic groups. Masculine digit ratios are linked to aggression, competitiveness, and certain health issues, while feminine ratios are linked to athletic ability and certain mental illnesses.
The term “digit ratio” can refer to the relative lengths of two fingers or toes, but is almost always used to refer specifically to the relative lengths of a person’s ring and index fingers. This is commonly called a 2D:4D ratio, referring to the respective positions of the index and ring fingers as the second and fourth digits of the hand. The ratio is calculated by dividing the length of the right index finger by the length of the right ring finger, so a ratio less than 1 indicates that the ring finger is longer and a ratio greater than 1 indicates the opposite. Scientific research has shown a correlation between differences in digit ratio and a number of physical and psychological traits.
This ratio of figures is an example of human sexual dimorphism, physical differences between men and women. Most men have their ring fingers longer than their index fingers, and most women have their index fingers the same length as their ring fingers, or longer. A fetus’ development in the womb is driven by the type of hormones it is exposed to, which influence the development of the fetus’ genitalia and other sex-specific structures and traits.
The male anatomy develops in response to the presence of higher levels of what are called androgen hormones, such as testosterone. This includes differences in the relative sizes of different brain areas, compared to the average female. One of the effects of androgen hormones is the relatively longer ring finger and relatively shorter index finger. Why this should be the case is not yet known, although sexual dimorphism in the relative lengths of the different digits has been observed in other species such as gorillas and chimpanzees. Male-to-female differences in toe ratio are one of the few physical sex differences that are quite apparent from birth and do not result from hormonal changes during puberty.
A number of personal traits tend to correlate with digit ratio, although the correspondence between a particular digit ratio and particular mental and physical characteristics is by no means absolute. Mean digit lengths and ratios also vary among different ethnic groups for reasons of heredity rather than in utero testosterone exposure, which further complicates attempts to use digit ratios as a predictor. Longer ring fingers and a more masculine digit ratio have been shown in studies to be positively correlated with increased aggression, assertiveness, and competitive behavior. Male digit ratios are also disproportionately common in autistic or left-handed people.
Ratios of more masculine digits in men correlate positively with traits such as more masculine facial features, higher sperm count, and musical ability. Male digit ratios in women are positively correlated with traits such as high achievement in competitive sports and health problems that are more common in males than females, such as heart disease. More masculine digit ratios are also positively correlated with homosexuality in females, but most research has shown no difference in digit ratios between heterosexual and homosexual men. More masculine digit ratios are especially common in men who have prostate cancer, and more feminine digit ratios are more common among people with eating disorders and schizophrenia.
Protect your devices with Threat Protection by NordVPN
