Sex Estimation from the Pelvis Discriminant Functions for Quantitative Indices in a Modern Yucatecan Population

Abstract

This study develops nine discriminant functions based on a series of indices calculated on the human pelvic bones from a modern forensic Mexican skeletal population of Maya ancestry from the state of Yucatan. The skeletal collection consists of individuals of known sex and age. Linear measurements were recorded using straight digital and spreading calipers, while the subpubic angle was calculated by means of a 180-degree protractor. Indices that yielded a statistically significant difference between males and females (α = 0.05) were used to calculate discriminant functions, which were then applied to a control sample. Results indicate that the pubic region provides the most reliable estimates of sex, with values ranging between 89.7% and 100.0%. They were followed by the maximum height/ width of the pelvic bone (accuracy of 96.4% and 82.4%, respectively, for males and females) and by the symmetry/asymmetry of the greater sciatic notch (89.7% in males and 88.2% in females). The other indices yielded lower levels of accuracy, ranging between 43.7% and 75.9%. Nonetheless, these less reliable indices are still useful in cases of taphonomically damaged pelvic bones. These discriminant functions are less likely to be affected by subjectivity, individual size, and robusticity and confirm that the male pelvis is narrower and taller than the female one. Compared to qualitative traits, mathematically calculated indices reduce intra-and interobserver error. Last, being developed on a specific population, it will be important to test their applicability to other ethnic groups.