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

Abstract

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 (p<.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.”

Acknowledgements

We thank Jin Ping, Raymond Yaoshi Tian, Guobiao Tsai, Yun Tao, Songbai Xue, Fufei Yang, Haijun Qu, Tao Liu, Feng Shu and Xinyu Deng for their help with this project. For advice concerning testosterone assays, we thank Doug Granger, Susan Lipson and Peter Ellison. The Green Fund provided financial support for this project.