The test of competing models for the prehistoric peopling of the Azapa Valley, northern Chile, using matrix correlations

Abstract

This study reports biodistances from nonmetric dental traits for eleven mortuary samples -an Andean Paleoindian sample, a Tiwanaku sample, and nine from the Azapa Valley- to test three models for the prehistoric population dynamics of the Azapa Valley, Chile, using matrix correlation analysis of hypothetical design matrices. These models include: (1) Tiwanaku colonization during the Middle Period, (2) simple gene flow over time, and (3) a modified gene flow model with coastal groups demonstrating genetic continuity while diverging from valley populations. The Tiwanaku sample demonstrates significant biodistances with five of the nine Azapa Valley samples, and large but nonsignificant differences with all but the late Desarrollo Regional Gentilar sample from Azapa-8. Inland samples from the Azapa Valley generally become more similar to the Tiwanaku sample through time suggesting gene flow, while coastal samples of the region demonstrate a degree of epigenetic coherence. The results of Mantel tests for each of the three design matrices indicates that the Tiwanaku and simple gene flow models produce nonsignificant and low correlations with the biodistance matrix while the gene flow with coastal divergence model produces significant results. The implications of these results are discussed.