Manning J T, Trivers R L, Thornhill R, Singh D
University of Liverpool, UK.
Laterality. 2000 Apr;5(2):121-32.
Testosterone, particularly prenatal testosterone, has been implicated in the aetiology of many extragenital sexually dimorphic traits. It is difficult to test directly for the effect of prenatal testosterone in humans. However, Manning, Scutt, Wilson, and Lewis-Jones (1998b) have recently shown that the ratio of the length of the 2nd and 4th digits (2D:4D) in right hands negatively predicts testosterone levels in men. As digit ratios are fixed in utero it may be that the 2D:4D ratio is associated with many prenatally determined sexually dimorphic traits. We tested this for one case by examining the relationship between lateralised hand performance (LHP), as measured by an Annett peg board, and 2D:4D ratio in rural Jamaican children. 2D:4D ratio was measured from photocopies and X rays of hands. A low 2D:4D ratio in the right hand of boys and girls (photocopies) and the right hand of boys only (X rays) was associated with a reduction in rightward performance asymmetry. In both samples the difference in 2D:4D ratio between the hands (2D:4D left hand-2D:4D right hand) showed the strongest relationship with LHP i.e. high ratio in the left and low in the right correlated with a tendency towards a fast performance with the left hand. It is suggested that the 2D:4D ratio may be associated with the expression of other sexually dimorphic behavioural traits.
睾酮，尤其是产前睾酮，被认为与许多生殖器外性二态性特征的病因有关。直接检测产前睾酮对人类的影响很困难。然而，曼宁、斯卡特、威尔逊和刘易斯 - 琼斯（1998b）最近表明，右手第二和第四指长度之比（2D:4D）与男性的睾酮水平呈负相关。由于指长比在子宫内就已固定，所以2D:4D比例可能与许多产前确定的性二态性特征相关。我们通过研究牙买加农村儿童中用安尼特钉板测量的偏侧手表现（LHP）与2D:4D比例之间的关系，对这一情况进行了测试。2D:4D比例是从手的影印件和X光片中测量的。男孩和女孩右手（影印件）以及仅男孩右手（X光片）的低2D:4D比例与向右表现不对称的减少有关。在两个样本中，双手之间的2D:4D比例差异（左手2D:4D - 右手2D:4D）与LHP的关系最为密切，即左手比例高而右手比例低与左手快速表现的倾向相关。有人认为，2D:4D比例可能与其他性二态性行为特征的表达有关。
