Second to fourth digit ratios, sex differences, and behavior in Chinese men and women

The ratio of the length of the second and fourth digits (2D:4D ratio) is consistently smaller in men than in women. Additionally, within each sex, smaller digit ratios may be associated with higher testosterone levels and/or more masculine attitudes and behaviors, although these findings are less consistent. We assessed 2D:4D ratios, together with measures of masculine attitudes and behaviors, in an ethnically homogeneous population of 118 men and 103 women, aged 21-38, all heterosexual and right-handed, in Beijing, China. In men, we also measured salivary testosterone levels. As predicted, men displayed significantly smaller 2D:4D ratios than women (pB.0001 in both hands). Within each sex, however, 2D:4D ratios, measures of masculine characteristics, and salivary testosterone showed no significant associations with one another. These latter null findings may partially reflect cultural differences in definitions of "masculinity".