Rahman Qazi
School of Psychology, University of East London, The Green, London, UK.
Psychoneuroendocrinology. 2005 May;30(4):382-91. doi: 10.1016/j.psyneuen.2004.10.006. Epub 2005 Jan 13.
Sexual orientation in humans may be influenced by levels of prenatal sex steroids which canalise neurodevelopment along sex-typical (heterosexual) or sex-atypical (homosexual) lines. Some evidence for sexual-orientation-related differences in putative somatic markers of prenatal sex hormones supports this view. A competing theory asserts that human homosexuality is due to developmental instability (DI) because it represents a shift from the species-typical pattern of heterosexual orientation. Evidence for elevated rates of non-right handedness among homosexuals provides limited support for this account. The current study tested both theories by examining nine bilateral somatic traits in 120 healthy heterosexual and homosexual men and women in order to compute second to fourth finger length ratios (2D:4D), a measure ascribed to levels of prenatal sex steroids, and fluctuating asymmetry (FA), a measure of DI. Homosexual men and women had significantly lower right hand 2D:4D ratios (even after controlling for handedness, height and weight differences) in comparison to heterosexuals, but sexual orientation did not relate to composite FA scores. The findings constrain the number of possible neurodevelopmental pathways responsible for sexual orientation in humans.
人类的性取向可能受到产前性类固醇水平的影响,这些激素会使神经发育沿着性别典型(异性恋)或性别非典型(同性恋)的方向发展。产前性激素假定的躯体标志物中与性取向相关的差异的一些证据支持了这一观点。一种与之竞争的理论认为,人类同性恋是由于发育不稳定性(DI),因为它代表了从物种典型的异性恋取向模式的转变。同性恋者中非右利手比例升高的证据为这一观点提供了有限的支持。本研究通过检查120名健康异性恋和同性恋男性及女性的九种双侧躯体特征来检验这两种理论,以便计算食指与无名指长度比(2D:4D),这是一种归因于产前性类固醇水平的指标,以及波动不对称性(FA),这是一种DI的指标。与异性恋者相比,同性恋男性和女性的右手2D:4D比值显著更低(即使在控制了利手、身高和体重差异之后),但性取向与综合FA分数无关。这些发现限制了人类性取向相关的可能神经发育途径的数量。