Mayhew T M, Gillam L, McDonald R, Ebling F J P
Centre for Integrated Systems Biology & Medicine and Institute of Neuroscience, School of Biomedical Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK.
J Anat. 2007 Nov;211(5):630-8. doi: 10.1111/j.1469-7580.2007.00801.x. Epub 2007 Aug 31.
It is known that there are sexually dimorphic differences in relative and absolute lengths of the index (2nd) and ring (4th) fingers and that the sizes of laterally-paired soft tissues (e.g. ears and fingers) show changes across the menstrual cycle. The aim of the present study was to determine whether cyclical changes in the digit lengths of the index and ring fingers also occur and, if so, to what extent these are related to changing patterns of circulating sex steroids. Digit lengths were assessed over two cycles in groups of right-handed females (19-21 years of age) who were divided on the basis of whether or not they were taking oral contraceptive pills (n = 13 and n = 6 respectively). Using callipers, finger lengths were measured on photocopy images of both hands taken at 4-day intervals for a total of 56 days. We tested the following null hypotheses: (1) digit length measurements do not exhibit fluctuations across the menstrual cycle; (2) there is no evidence of lateral asymmetry between measurements made on both hands; (3) the lengths of digits 2 and 4 do not differ in either hand. Null hypotheses were tested using Page's L trends test for related samples (cyclical fluctuations) and paired Student's t tests (left-right asymmetries and within-hand digital differences). In those not taking oral contraceptives, finger lengths and 2D:4D digit ratios fluctuated across the cycle with values tending to increase in the pre-ovulatory period and decline thereafter. Left-right asymmetries varied in a similar fashion with lengths generally being larger, and lateral asymmetries smaller, in the dominant hand. Although sample sizes were smaller, some of these patterns were retained but others were perturbed in those practising oral contraception. We conclude that finger lengths are cycle-dependent and that account should be taken of this, and of oral contraceptive usage, in future studies on female digit lengths and their ratios.
已知食指（第二指）和无名指（第四指）的相对长度和绝对长度存在性别差异，并且左右对称的软组织（如耳朵和手指）的大小在月经周期中会发生变化。本研究的目的是确定食指和无名指的指长是否也会发生周期性变化，如果是，这些变化在多大程度上与循环性类固醇的变化模式相关。对19 - 21岁的右利手女性进行了两个周期的指长评估，这些女性根据是否服用口服避孕药分为两组（分别为n = 13和n = 6）。使用卡尺，每隔4天对双手的影印图像测量手指长度，共测量56天。我们检验了以下零假设：（1）指长测量在月经周期中不呈现波动；（2）双手测量之间没有左右不对称的证据；（3）双手的第二指和第四指长度没有差异。使用Page's L趋势检验对相关样本（周期性波动）以及配对学生t检验（左右不对称和手内指长差异）来检验零假设。在未服用口服避孕药的女性中，手指长度和2D:4D指长比在周期中波动，在排卵前期值趋于增加，此后下降。左右不对称情况以类似方式变化，优势手的长度通常更大，左右不对称性更小。尽管样本量较小，但在服用口服避孕药的女性中仍保留了一些这些模式，但其他模式受到了干扰。我们得出结论，手指长度依赖于周期，在未来关于女性指长及其比例的研究中应考虑到这一点以及口服避孕药的使用情况。
