Evaluating the Accuracy of Cranial Indices in Ancestry Estimation Among South African Groups

Historically, population differences were quantified using cranial indices. Even though the application of indices is associated with numerous statistical and methodological problems, the use of cranial indices to estimate ancestry persists as demonstrated by its inclusion in several recent papers and conference presentations. The purpose of this study was to classify 207 South African crania and compare the results of five standard cranial indices to linear discriminant analysis (LDA). New sectioning points were created to contend with low classification accuracies (40–79%) and possible secular trends. Although the accuracies of the new sectioning points increased (66–87%), the accuracies associated with the stepwise LDA were higher (84%) and could classify the crania into one of the three South African groups. The results of the study demonstrate that indices cannot compete with multivariate techniques and should not be used in forensic anthropological analyses for ancestry estimation.