Institute of Anthropology, Liaoning Medical University, Jinzhou, 121001, People's Republic of China,
Arch Sex Behav. 2014 Feb;43(2):329-33. doi: 10.1007/s10508-013-0179-9. Epub 2013 Sep 7.
The digit ratio (2D:4D) is sexually dimorphic and has been considered an indicator of prenatal sex hormone exposure. Previous studies have shown that males tend to have lower 2D to 4D ratio than females, and this sexual dimorphism has been reported across different ethnic groups and different countries. However, digit ratio data are missing from the Han ethnicity in China. Furthermore, most of the previous studies used direct measurement for digit ratio. In this article, we used multiple measurement methods, including the direct measurement and two X-ray measurement methods to examine the trait of 2D:4D in Chinese Han. Our sample consisted of 128 men and 122 women from Liaoning Medical University. They were 18-20 years old. The direct measurement and two types of X-ray measurements of the length of their 2nd and 4th fingers were used separately to calculate digit ratios. Soft tissue thickness of 2D and 4D fingertips were also assessed from the two X-ray methods. The results suggest that (1) sex differences in 2D:4D tend to be stronger in the two X-ray measurements in comparison to the direct measurement; (2) 2D:4D ratios from X-ray measurements tend to be lower than that from the direct measurement; (3) Han ethnicity have a lower mean value of 2D:4D than other ethnic groups; (4) no sex difference in the soft tissue of finger tips. In conclusion, the digit ratio is lower in both men and women in Han, and the sexual dimorphism in digit ratio was stronger with X-ray measurements in comparison to the direct measurement.
指长比（2D:4D）具有性别二态性，被认为是产前性激素暴露的指标。先前的研究表明，男性的 2D:4D 比值通常低于女性，这种性别二态性在不同种族和不同国家都有报道。然而，中国汉族人群的指长比数据缺失。此外，大多数先前的研究使用直接测量法来测量指长比。在本文中，我们使用了多种测量方法，包括直接测量法和两种 X 射线测量法，来研究中国汉族人群的 2D:4D 特征。我们的样本由来自辽宁医学院的 128 名男性和 122 名女性组成，年龄在 18-20 岁之间。我们分别使用直接测量法和两种 X 射线测量法测量了他们的第二和第四指的长度，并计算了指长比。我们还从两种 X 射线方法中评估了第二和第四指指尖的软组织厚度。结果表明：（1）与直接测量法相比，X 射线测量法得出的 2D:4D 性别差异更大；（2）X 射线测量法得出的 2D:4D 比值往往低于直接测量法；（3）汉族的 2D:4D 平均值低于其他种族；（4）指尖软组织没有性别差异。总之，汉族人群中男性和女性的指长比都较低，与直接测量法相比，X 射线测量法的性别二态性更强。
