Long-term processes between Classic and Postclassic populations in the Mexico basin

The study of nonmetric traits is useful for establishing biological differences or affinities between populations. This study considered 12 nonmetric cranial characters. The objective is to compare five series of two different cultural horizons: three populations of the Teotihuacán Classic period and two of the Mexica Postclassic period. For the selection of nonmetric traits, those not altered by intentional cephalic modification were considered. From the sample of materials, it was assessed whether the populations of the Classic period could have biological and cultural affinity between them, making a migratory interpretation which indicates differences in nonmetric characters between them. The mean measure of divergence (MMD) was considered as bio-distance. The distance matrix was analyzed using the unweighted pair group method with arithmetic mean and nonmetric multidimensional scaling. Frequencies were studied using the principal component analysis. Mantel test and partial Mantel test were used to compare the distance matrix obtained with the MMD with sites geographical distance matrix, type of settlements matrix, and period of the site's matrix. In none of those cases were found a correlation at the $\alpha =0.05$ level. Making more plausible that the results of the nonmetric traits MMD matrix agree with a migration process. All methods agree on separating Classical populations into one group and Postclassic populations into another. The archeological contexts, and the study of the material culture found, agree with the analysis of nonmetric characters.