Sexual Dimorphism in America: Geometric Morphometric Analysis of the Craniofacial Region

The study found that sex, but not size, had a significant influence on shape in both American Whites and Blacks. In contrast to the findings of Rosas and Bastir, the current study found that size did not have a significant influence on shape in either Whites or Blacks. This means that smaller and larger individuals within the same sex in the study samples are similar in shape; e.g., White females are of similar shape regardless of size. Moreover, the average cranial size of males was found to be different than the female means in both groups, indicating that there is significant sexual dimorphism present; however, the pattern of sexual dimorphism in shape does differ among groups. Using both size and shape outperforms discriminant functions developed from traditional metrics. The study used three-dimensional coordinates of 16 standard craniofacial landmarks, which were collected with a Microscribe-3DX digitizer and the program ThreeSkull. The sample consisted of 118 adults of known sex and ancestry (30 White males, 30 White females, 29 Black males, and 29 Black females) from the W.M. Bass Donated Collection and the Forensic Data Bank. The methods used are described. 6 tables, 4 figures, and 13 references