Trivers Robert, Manning John, Jacobson Amy
Department of Anthropology, Rutgers University, New Brunswick, NJ 08901-1414, USA.
Horm Behav. 2006 Feb;49(2):150-6. doi: 10.1016/j.yhbeh.2005.05.023. Epub 2005 Jul 22.
It has been hypothesised that the ratio between the length of the 2nd and 4th digits (2D:4D) is a correlate of prenatal sex steroids, and this relationship is strongest for the right hand. Furthermore, it has been suggested that 2D:4D is sexually dimorphic, the dimorphism is determined early, and 2D:4D among children is stable with growth. Here, we present the first longitudinal study of right and left hand 2D:4D. Our sample was 108 (54 males) Jamaican children. The first measurements were made in 1998 when mean age was 9.68 +/- 1.39 years, and a second set of measurements were made in 2002. We found that: (i) there was a small increase in 2D:4D with age which was lowest in the right hand; (ii) 2D:4D was sexually dimorphic, the means for males and females differed in the same direction in the 1998 and 2002 samples, and the sex difference was significant in the 1998 but not in the 2002 sample; (iii) the correlation between the 1998 and 2002 measurements of 2D:4D was high, indicating that rank order of the ratio was stable across year groups; and (iv) the rate of change in 2D:4D did not differ significantly across year groups. We conclude that 2D:4D increases slightly with age in children with the effect less marked for the right hand (i.e. the hand which is likely to show the strongest association with prenatal steroids), 2D:4D is sexually dimorphic from an early age, and the rank order of 2D:4D is stable in children. We discuss the implications of our findings for the status of 2D:4D as a correlate of prenatal sex steroids. The patterns of change in other finger ratios are also considered.
有假说认为，第二和第四指长度之比（2D:4D）与产前性类固醇有关，且这种关系在右手最为明显。此外，有研究表明2D:4D具有性别二态性，这种二态性在早期就已确定，并且儿童的2D:4D会随着生长而保持稳定。在此，我们首次对右手和左手的2D:4D进行了纵向研究。我们的样本是108名牙买加儿童（54名男性）。首次测量于1998年进行，当时平均年龄为9.68±1.39岁，第二次测量于2002年进行。我们发现：（i）2D:4D随年龄略有增加，但右手的增加幅度最小；（ii）2D:4D具有性别二态性，1998年和2002年样本中男性和女性的均值变化方向相同，1998年样本中的性别差异显著，但2002年样本中不显著；（iii）1998年和2002年2D:4D测量值之间的相关性很高，表明该比例在不同年龄组中的排序是稳定的；（iv）不同年龄组中2D:4D的变化率没有显著差异。我们得出结论，儿童的2D:4D随年龄略有增加，右手的变化不太明显（即右手可能与产前类固醇的关联最强），2D:4D从幼年起就具有性别二态性，并且儿童的2D:4D排序是稳定的。我们讨论了研究结果对2D:4D作为产前性类固醇相关指标的意义。同时也考虑了其他手指比例的变化模式。
