The Second‐to‐Fourth Digit Ratio is not different between Sexes despite Differences in all Phalanxes: An Analysis of Phalanxes via Radiographic Measurement

The second‐to‐fourth digit ratio (2D:4D) has gained ground as a surrogate measurement for intrauterine steroid exposure. That is, studies have demonstrated (mainly via measurements from flexion creases to finger tips) that females tend to have a longer second digit relative to fourth digit whereas, in males, the opposite is true. This study aimed to assess the 2D:4D via photogrammetric analysis of PA right‐side dominant hand radiographs. A total of 984 phalanxes from 164 hands were measured for length (804 phalanxes from 134 female hands; 180 phalanxes from 30 male hands) by a researcher blinded to sex. The proximal, middle, and distal phalanx lengths from both the second and fourth digits were all significantly different between sexes (2D: p=0.001, p=0.003, p=0.0002; 4D: p=0.0007, p=0.0005, p=0.00004). The 2D:4D averaged 0.93±0.09 (Mean±SD) for females and 0.92±0.17 for males. There was no statistically significant difference in 2D:4D ratio between sexes (p=0.228). The results of this study, suggest that phalanx length may be beneficial in, for example, forensic or anthropological identification of remains via phalanxes. This study also suggests that results of 2D:4D ratio studies should be re‐evaluated. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .