Geometric morphometric assessment of sexually dimorphic characteristics of the distal humerus

Abstract

A number of recent studies investigated the use of morphological characteristics of the distal humerus to estimate the sex of unknown individuals. Using visual assessment, accuracies ranging from 74% to more than 90% were reported. The aim of this study was to assess these traits with geometric morphometrics, in order to determine if they corroborate the findings as described with pure visual assessment. A total sample of 155 female and 175 male humeri of South Africans were used. All humeri were photographed in standardized positions from a posterior and inferior view, and homologous landmarks assigned. Olecranon fossa shape, angle of the medial epicondyle and trochlear symmetry were assessed. Males and females could be separated with accuracies ranging from 78 -91%. The results of this study confirm the existence of these traits and their usability in assessment of sex from skeletal remains, and the observed anatomical characteristics largely agree with what have been described by visual assessment.KEY WORDS forensic anthropology, sex determination, distal humerus, sexual dimorphism, South Africa, olecranon fossa shape, trochlear symmetry 2

Outline Shape Analysis on the Trochlear Constriction and Olecranon Fossa of the Humerus: Insights for Sex Estimation and a New Computational Tool,

“…; also see ). The latter described the ellipsoidal outline of the olecranon fossa and was recorded clockwise starting from its most inferior aspect, using landmarks 1, 2, 3 and 4 adapted from Vance and Steyn as guides (Fig. ).…”

“…The first evaluated the constriction of the trochlea, it is defined as the sinusoidal curve reaching from the most medial inferior aspect to the most lateral inferior aspect of the trochlea, constrained by the landmarks at both endpoints (a,c), and must pass through the landmark placed between at the greatest constriction point (Fig. ; also see ). The latter described the ellipsoidal outline of the olecranon fossa and was recorded clockwise starting from its most inferior aspect, using landmarks 1, 2, 3 and 4 adapted from Vance and Steyn as guides (Fig.…”

“…It was placed on the ridge that begins on the inferior edge of the olecranon fossa and is situated in the middle of landmark 2 and 4; 2) the most lateral point of the olecranon fossa seen on the posterior surface, this landmark was placed on the lateral edge of the fossa; 3) the most superior point of the olecranon fossa; and 4) the most medial point of the olecranon fossa. Definitions following Vance and Steyn . [Color figure can be viewed at wileyonlinelibrary.com]…”

“…However, there are situations when not all routinely consulted skeletal components are available, or they exhibit postmortem damage to the regions useful for applying sex estimation methods. Therefore, many alternative methods can be found in the literature, most of the time resorting to craniometrics or to linear measurements of long bones , and some employing geometric morphometrics to landmark‐based protocols of data collection .…”

“…Tests of this method in different populations have correctly classified 74–82% of the individuals. An attempt at a landmark‐based geometric morphometrics reinterpretation of the method by Vance and Steyn reports slightly higher accuracies between 78–91% but presented no straightforward way for others to apply it to undiagnosed individuals.…”