A geometric morphometric study into the sexual dimorphism of the human scapula

Abstract

Sex determination is vital when attempting to establish identity from skeletal remains. Two methodological approaches to sex determination exist: morphological and metrical. The aim of this research paper was to use geometric morphometrics to study the shape of the scapula and its effect on the sexual dimorphism the scapula. The sample comprised of 45 adult black male and 45 adult black female scapulae of known individuals. The scapulae were photographed and 21 homologous landmarks were plotted to use for geometric morphometric analysis with the 'tps' series of programs, as well as the IMP package. Consensus thin-plate splines and vector plots for males and females were compared. The CVA and TwoGroup analyses indicated that significant differences exist between males and females. The lateral and medial borders of females are straighter while the supraspinous fossa is more convexly curved than that of males. More than 91% of the females and 95% of the males were correctly assigned. Hotelling's T 2 -test yielded a significant p-value of 0.00039. In addition, 100 equidistant landmarks representing the curve only were also assigned. These, however, yielded considerably poorer results. It is concluded that it is better to use homologous landmarks rather than curve data only, as it is most probable the shape of the outline relative to the fixed homologous points on the scapula that provides the separation.3

Morphometric analysis of scapula to determine sexual dimorphism

“…[10] Y Scoltz found >91% accuracy for female and >95% accuracy for male in his study. [11] Ozer reported 82.9% -95% accuracy with highest accuracy for maximum scapular breadth. [12] Previous studies suggested that use of multiple variables give higher accuracy compared to the studies using single variable.…”

Sex Determination in Egyptian Population from Scapula by Computed Tomography

“…Throughout life the scapular changes are not significant after development is finished [5,6], depending on these assumptions, researches already inspected the sexual diversity of the scapula in different populations [7]. With expanding interest for accurate sex determination; it is important to enhance variable estimation methods [8].…”

“…Previous studies were done on determination of sex from scapula in different populations using either skeletal remains [1,3,[10][11][12][13][14][15], digital photographs [5,16] or multi -slice computed tomography (CT) [2,4,7,17,18] on different age groups and using different measurements. To the best of our insight, this Egyptian study is an interesting one which uses both scapulae in the determination of sex in Egyptians with different dimensions and different age group.…”

Geometric morphometric assessment of sexually dimorphic characteristics of the distal humerus

“…It allows for a detailed assessment of various aspects that may contribute towards differences in shape, and can also quantify the accuracies with which skeletons can be sorted into various groupings (e.g., sex) based on the observed shape differences. Two-and three-dimensional geometric morphometric assessments have been used to study sexual dimorphism in, for example, the skull (Rosas & Bastir, 2002;Bigoni et al, 2010), mandible (Oettlé et al, 2005;Franklin et al, 2007;Franklin et al, 2008), pelvis (Steyn et al, 2004;Gonzalez et al, 2009); and scapula (Scholtz et al, 2010). Kranioti et al (2009) also used geometric morphometrics to study shape differences in the proximal and distal ends of the humerus.…”