Nonmetric cranial trait variation and prehistoric biocultural change in the Azapa Valley, Chile

Historically, interpretations of both biological and cultural change within the prehistoric Azapa Valley, northern Chile, have cited large-scale population movements, with replacement from complex societies located in the adjacent highlands to the east. Biological estimates of this change have traditionally relied upon biodistance estimates, using craniofacial measures of both deformed and nondeformed skulls. In order to evaluate whether large-scale prehistoric migrations occurred in the Azapa Valley, we examine biodistance results from nonmetric cranial traits for eight mortuary samples that represent all time periods of prehistoric occupation of the valley. None of the mean measures of divergences (MMD) among mortuary samples examined by this study were significant. These results suggest biological continuity in the Azapa Valley during 5,000 years of prehistory, with nonsignificant gene flow during the late Middle Horizon (AD 750-1100) and Late Intermediate (AD 1100-1476) periods. Biodistance results also suggest endogamy within coastal and inland populations. The broader implications of these results are discussed.