Striking out and digging in: A bioarchaeological perspective on the impacts of the Wari expansion on populations in the Peruvian central highlands.

The Wari empire emerged near the present day city of Ayacucho, Peru around AD 600 and collapsed approximately 400 years later. There is no doubt that Wari influence was widespread in the Andes; however, the extent to which the empire successfully integrated regional territories is not as well understood. This study examined the impact of the rise and fall of the Wari empire on the structure of interaction between populations hypothesized to have been within its sphere of influence. The relative frequencies of cranial non-metric traits were used to explore biological affinities among 17 populations that lived during and after the Wari empire. The samples include populations from regions with archaeological evidence of Wari influence. A basic premise of this study is that the economic, ideological, and political goals of the Wari created a cultural horizon that would have increased contact between regional populations that would in turn lead to gene flow and patterned differences in biological affinities between groups.

On a large scale results indicated that the Wari empire did not have a significant impact on gene flow in the central Andes. However, several suggestive patterns were observed when the data were examined on the smaller regional scale. The mechanisms by which Wari influence spread within and between regions is not easily understood and consistency in ideology could be mistaken for similarity in social action and interaction. Biological distance analyses of regional populations were a useful proxy for unraveling the complex pattern of social interactions required to transmit the consistent Wari ideology that characterized the Middle Horizon. Results of this study support hypotheses regarding a strong relationship between the Wari and Nasca, add new detail to the current understanding of interaction within the Nazca Valley during the height of the Wari empire, find little evidence of intensive interaction between the Wari and populations in the north-central highlands, and suggest that dualistic social organization documented by Spanish chroniclers truly has a deep history in the Andes. The findings of this study are illustrative of the multivariate and unpredictable nature of imperial expansion.