Assessing the Potential of Ilium Outlines, Greater Sciatic Notch Metrics, and Indices of Pubic/Ischial Length for Subadult Sex Estimation

• NCJ Number: 254256
• Journal: American Journal of Physical Anthropology Volume: 168 Dated: 2019 Pages: 83-83
• Author(s): Heather M. Garvin; Kieran Severa; Elizabeth Ternent; Michala K. Stock; Laura Cirillo; Kyra E. Stull
• Date Published: 2019
• Length: 1 page
• Grant Number(s): 2015-DN-BX-K409
• Agencies: NIJ-Sponsored
• Publication Type: Research (Applied/Empirical); Report (Study/Research); Report (Grant Sponsored); Program/Project Description
• Award: Development of Modern Subadult Standards: Improved Age and Sex Estimation in U.S. Forensic Practice

Annotation

Since previous studies on subadult pelvic sexual dimorphism present varying results, depending on the samples, variables, and methods applied, the current study used a modern sample of subadult postmortem CT scans to investigate the utility of ilium outlines, greater sciatic notch (GSN) measurements, and indices of pubic/ischial length in subadult sex estimation.

Abstract

The pelves of 202 subadults (neonate to 10 years of age) were segmented and 3D surface models created. Ilium orientation was standardized and two-dimensional contour outlines were collected and subjected to elliptical Fourier and principal component analyses. GSN length, depth, and angle, along with pubic and ischial lengths, were collected from the 3D models. M/ANCOVA and discriminant function analyses (DFA) were performed on the principal components and pelvic metrics. ANCOVA results indicate significant (p< 0.05) sexual dimorphism in components related to the ilium outline, although DFA correctly classified only 60.4 percent of the total sample. Systematically re-running analyses excluding the youngest age cohorts at 1 year intervals (e.g., including all individuals >1yr, all individuals >2yr, etc.), revealed that by the age of four, correct classification increases to 77.4 percent, although the sample size was limited to 31 individuals. Correct classification using GSN variables did not exceed 64 percent, regardless of the age cohorts or variables included. The pubic/ischial indices displayed no significant sex differences. These results suggest that pelvic sex estimation is unreliable in young children, but that ilium shape may be undergoing sexual differentiation by the age of five. Larger samples of subadults in these mid-childhood ages are needed for further testing. (publisher abstract modified)