The Second‐to‐Fourth Digit Bone Area Ratio from Radiographic Images

Second‐to‐fourth digit ratio has been posited as a sexually dimorphic trait. Reportedly, females have a longer second digit relative to fourth digit and males have a longer fourth digit relative to second digit. This study assessed for differences in the size and shapes of the phalanxes from the second and fourth digits in 30 females (180 phalanxes) via radiographs of their right hands (all right‐hand dominant). Principle component analysis demonstrated differences between phalanxes. The area within the radiographic outlines of each phalanx were calculated. The areas of the phalanxes of the 4 th digit were significantly larger than those of the 2 nd digit. (Proximal phalanx: p=0.002; Middle phalanx: p<0.00001; Distal phalanx: p<0.00001). Further the phalanxes followed a trend, in both the second and fourth digits, where the middle phalanx was approximately twice the area of the distal phalanx and the proximal phalanx was approximately twice the area of the middle phalanx. The results of this study provide preliminary information that may be helpful in differentiating between phalanxes of the 2 nd and 4 th digits in human remains. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .