Georgiev Alexander V, Ryan Calen P, Gettler Lee T, McDade Thomas W, Kuzawa Christopher W
Department of Anthropology, Northwestern University, Evanston, Illinois.
Department of Anthropology, University of Notre Dame, Notre Dame, Indiana.
Am J Phys Anthropol. 2017 Jul;163(3):437-445. doi: 10.1002/ajpa.23215. Epub 2017 Mar 27.
A low second-to-fourth (2D:4D) digit ratio, a retrospective marker of high prenatal androgens, predicts increased investment in costly sexually dimorphic traits in men in some studies, although results are mixed. Here we test the hypothesis that the association of low 2D:4D ratios with increased muscularity and decreased adiposity depends on current testosterone (T) levels, such that digit ratio will be a particularly strong predictor of outcomes among men exhibiting a mating-effort-oriented endocrinological profile (high T). We also test the association between 2D:4D and somatic traits independently of T.
We related 2D:4D digit ratios, and their interaction with T, to handgrip strength, lean mass, arm muscle area, and skinfold thickness in a sample of young, childess men (20-22 y) from Cebu, Philippines (N = 623).
Digit ratio did not significantly predict men's T-dependent somatic traits. Interactions between 2D:4D and morning T, similarly, did not predict male muscularity or adiposity. Although two of the interactions were significant or marginally significant (p < .1), after adjusting for multiple testing the evidence in support of our hypothesis was weak.
We found no evidence that 2D:4D predicted measures of somatic reproductive effort in this sample of young men from Cebu, who as a group could be considered mostly mating-oriented. These relationships were also not contingent upon, or stronger, when considering the moderating effect of concurrent T levels. In this sample, 2D:4D was therefore either a poor proxy of prenatal androgen exposure or prenatal androgens had limited influence on adult somatic outcomes.
低的食指与无名指指长比（2D:4D）是产前雄激素水平高的一种回顾性标志，在一些研究中，它预示着男性在代价高昂的两性异形性状上的投入增加，尽管结果不一。在此，我们检验这样一个假设，即低2D:4D指长比与肌肉量增加和体脂减少之间的关联取决于当前的睾酮（T）水平，以至于指长比在表现出以交配努力为导向的内分泌特征（高T）的男性中，将是结果的一个特别强的预测指标。我们还独立于T来检验2D:4D与身体特征之间的关联。
我们将2D:4D指长比及其与T的相互作用，与来自菲律宾宿务的年轻未育男性（20 - 22岁）样本（N = 623）的握力、去脂体重、手臂肌肉面积和皮褶厚度联系起来。
指长比并未显著预测男性依赖T的身体特征。同样，2D:4D与早晨T之间的相互作用也未预测男性的肌肉量或体脂。尽管其中两个相互作用显著或接近显著（p < 0.1），但在进行多重检验校正后，支持我们假设的证据很薄弱。
在这个来自宿务的年轻男性样本中，我们没有发现证据表明2D:4D能预测身体生殖努力的指标，该样本总体上可被认为主要以交配为导向。在考虑同时存在的T水平的调节作用时，这些关系也不是取决于或更强。因此，在这个样本中，2D:4D要么是产前雄激素暴露的一个不良指标，要么产前雄激素对成年身体结果的影响有限。
