PNAS：性欲强弱与无名指长短有关

2011/09/10 20:46:32

女人想找寻另一半，或许得将男人无名指的长短列入考虑，因为这与男性的性欲有关。

据“中央社”报道，美国科学家发现，无名指的长度确实是由子宫内男女性荷尔蒙含量决定。

婴儿接触到愈多男性荷尔蒙睪丸素，无名指就可能愈长。

这项研究首度说明，男性的无名指为何通常比食指长。女性则是相反。

无名指长短以往被认为与精子数量、侵略行为、性倾向及运动细胞有关。而高睪丸素则与性欲较强相关。

佛罗里达大学(University of Florida)生物学家马丁与郑祯贵(音译，Zhengui Zheng)表示，无名指布满性荷尔蒙受体。

研究人员以怀孕老鼠作实验，并且控制影响老鼠雌激素与睪丸素含量的基因，结果显示，睪丸素增加会影响幼鼠后爪第4趾的长度。老鼠的趾头长度比例类似人类手指。

这项研究结果可能有助于了解前列腺癌与乳癌等与荷尔蒙失调有关的疾病。

Developmental basis of sexually dimorphic digit ratios

Zhengui Zheng and Martin J. Cohn

PNAS, 2011. 108 (39) 16289-16294; doi: 10.1073/pnas.1108312108

Males and females generally have different finger proportions. In males, digit 2 is shorter than digit 4, but in females digit 2 is the same length or longer than digit 4. The second- to fourth-digit (2D:4D) ratio correlates with numerous sexually dimorphic behavioral and physiological conditions. Although correlational studies suggest that digit ratios reflect prenatal exposure to androgen, the developmental mechanism underlying sexually dimorphic digit development remains unknown. Here we report that the 2D:4D ratio in mice is controlled by the balance of androgen to estrogen signaling during a narrow window of digit development. Androgen receptor (AR) and estrogen receptor α (ER-α) activity is higher in digit 4 than in digit 2. Inactivation of AR decreases growth of digit 4, which causes a higher 2D:4D ratio, whereas inactivation of ER-α increases growth of digit 4, which leads to a lower 2D:4D ratio. We also show that addition of androgen has the same effect as inactivation of ER and that addition of estrogen mimics the reduction of AR. Androgen and estrogen differentially regulate the network of genes that controls chondrocyte proliferation, leading to differential growth of digit 4 in males and females. These studies identify previously undescribed molecular dimorphisms between male and female limb buds and provide experimental evidence that the digit ratio is a lifelong signature of prenatal hormonal exposure. Our results also suggest that the 2D:4D ratio can serve as an indicator of disrupted endocrine signaling during early development, which may aid in the identification of fetal origins of adult diseases.