Analysis of Midfacial Human Cranial Morphology in Japanese, American White, and American Black Individuals Using the Digitized Angle Method

Abstract

The human cranium provides information regarding variation in ancestry, sex, and age, and anthropologists have been attempting to determine better methods to ascertain such information using cranial landmarks in quantitative analyses. Standard cranial measurements of linear inter-landmark distances have been commonly utilized to classify cranial and postcranial elements, while angle variables have been less frequently used—mainly due to the inability of older methods to accurately capture angles. However, in recent years, digitizers have allowed anthropologists to easily capture xyz coordinates, including angles, which are amenable to diverse quantitative analyses. This article examines eight midfacial angle variables, including those suggested by Howells (1973). A total of 198 dry male skulls (Japanese = 105; American White = 42; American Black = 51) and 44 dry female Japanese skulls from the World War II era were digitized with the stylus digitizer MicroScribe® (Revware, Inc., Raleigh, North Carolina) for, primarily, ancestry estimation using size and shape variables in the splanchnocranium. The eight angle variables were computed using mathematical equations in an Excel spreadsheet based on the captured xyz coordinates. Subsequently, discriminant function analyses using cross-validation were performed in the SPSS statistical software program. The results indicate that each group was correctly classified between 80% and 90% of the time using the angle variables alone, and the American Black individuals were classified the best at 86.3%. Accordingly, the digitized cranial angle method serves as a robust tool in classifying the three ancestral groups using only the midfacial region.