Distal Humerus Morphological Variation and Sex Estimation in Modern Thai Individuals.

Due to differential preservation, it is necessary to develop sex estimation methods on varied anatomical regions, including the distal humerus. Sexually dimorphic differences of the medial epicondyle angle, olecranon fossa shape, trochlear extension, and trochlear constriction have been documented in several non-Asian groups. This study examines distal humerus morphological variation in 616 modern Thai individuals (f = 198; m = 418) 18-96 years old and tests the methods on a hold-out sample of 152 individuals (f = 91; m = 61). The results indicate that population-specific binary probit regression performs the best (74.1-100%), followed by composite scoring (77.0-90.1%), binary logistic regression (63.3-92.2%), and univariate sectioning points (37.7-90.1%). Age minimally effects the expression of the medial epicondyle angle in males, and trait scoring is susceptible to high intra- and interobserver error. While demonstrating relatively high sex biases, distal humerus morphology can be used to estimate the sex of Thai individuals when more sexually dimorphic regions are absent.