Evaluation of bias in taxonomic classifications of cephalic index

Abstract

The cephalic index (ic) has been widely used as one of the higher profile tools to establish human taxonomy categories. Although it has been discussed the biological sense of the cephalic index, few studies analyzed the mathematics relations of the ratio and their classifications. In this paper, we address one of the biases introduced by the transformation into class categories (brachycephaly, mesocephaly and dolichocephaly)of the continuous distribution of ic, analyzing the effect in the population variance and the density of the data. Thus, we used Howells World Data Set for determination coefficient as an estimate of amount of information retained after processing ic categories. Our results indicate that the ratings of the ic are a haven of cranial biological variability of human populations. The adoption of hyperdimensional non-linear and multivariate models represents a better approach to the covariance of biological forms.