The biological affinities of the highland populations sampled in this study suggest that this group was genetically distinct from populations living to the west in the valleys and on the coast (Figures 6.3 and 6.4). Recent studies of both ancient DNA (aDNA) and modern DNA reveal similar patterns where Andean highlanders are very distinct from coastal populations. Many of these studies have been focused on the initial peopling of South America. For example Fuselli and colleagues (2003) have demonstrated a east-west pattern of differentiation where Andean populations comprise a unique and genetically
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al., 2010; Shinoda et al., 2006; Lewis et al., 2005). As discussed in the previous section Lewis et al. (2005) found that Ancash highlanders were similar to other Andean populations with respect to genetic heterogeneity. However, his findings also demonstrated a distinction between highland and coastal populations (see also Lewis et al. 2007a, 2007b). Hunley and Healy (2011) explored the possibility that European admixture was masking actual past evolutionary events when modern DNA was being considered. They found that although admixture may heighten the appearance of genetic differences between Andean and Amazonian populations, these large scale differences are accurately identified in DNA studies. Hunley and Healy (2011) also found that gene flow between neighboring populations had little effect on macrogeographic patterns in genetic diversity. Results indicating that the Wari cultural horizon had little impact on the overall central Andean population genetic structure, but almost certainly affected groups on the regional scale as reflected by the R matrices and FST values are congruent with
Hunley and Healy’s (2011) findings. 7.6 Summary of findings
The major finding of this study was that the collapse of the Wari empire had no significant impact on gene flow in the Peruvian Andes. A general pattern of isolation by distance was observed in the study populations, but temporal distance was not significantly correlated to biological distances when outlier populations were removed from the analysis. Many more nuanced regional patterns were revealed in their genetic structure when populations were analyzed in subsets. In particular, rates of gene flow in the Wari heartland did appear to have been affected the collapse; and the LIP population is relatively more isolated when compared to the MH populations. The study data also reflect a complicated relationship between Nasca populations and the Wari heartland during the MH. Another interesting, and more subtle, pattern emerged when the south-central highland samples were compared. This group was unique in this study because ethnohistoric data was available for comparison with archaeological and biological distance results. Here the biological distance results appeared to be in congruence with the historic data. In the north-central highlands samples a pattern of isolation emerged. These results were consistent with other studies of South American genetic variation, and may reflect linguistic differences among the sampled
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populations as well. All of these interpretations warrant further research. The possibility of studying larger, more representative osteological and material culture collections is constantly increasing as the political climate changes in Peru and more researchers and students become interested in the population and culture history of South America.
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Chapter VIII
Conclusions and Future Directions of Research
8.1 Conclusions
This study demonstrated that the cultural horizon fomented by the Wari empire in the Peruvian central Andes had no significant impact on social interaction on the pan-regional scale. The results do however; support the argument that imperialism is a dynamic process, and on the small scale there were dramatic variations in social interaction and organization. Furthermore, results indicated that the collapse of an empire is equally dynamic and should also be considered a process not an event. Regionally specific patterns in population genetic structure likely reflect flexibility in Wari imperial strategies and the unique approaches of individual communities when dealing with the Wari cultural horizon whether or not there was direct contact with the Wari empire. There is no strong evidence to suggest any of the populations sampled in this study were incorporated through military coercion (i.e. violence). Therefore, this study is largely reflective of the genetic consequences of hegemonic imperial power.
8.1.1 Complexity during the Middle Horizon
When compared to the LIP groups, populations from the MH did not have a higher rate of gene flow that might be expected during the Wari cultural horizon. However, the rates of gene flow appear to have varied amongst the MH populations that were sampled. The
Conchopata sample demonstrated biological affinity with the MH Turpo Qatun Rumi and Nasca populations. Archaeological investigation at Turpo Qatun Rumi and the Nazca Valley also indicated a strong Wari presence in both locations despite the large geographic distance between the Wari heartland and the Nazca Valley. Given archaeological evidence of Wari presence in Andahuaylas and the Nazca Valley and the apparent long-standing relationship between Ayacucho populations and the Nasca the biological distance results were not unexpected.
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The Nazca Valley samples, while similar to Wari heartland populations overall, demonstrated some interesting patterns within the valley. This may reflect resistance to
incorporation in the Wari empire by some Nasca communities. Others have hypothesized that a settlement shift away from Wari centers in the Nazca River valley during the MH was evidence of non-violent resistance (Schreiber, 2001; Conlee and Schreiber, 2006). Though not conclusive, the results of this study seem to indicate that the Nasca groups were not homogenous in their acceptance of Wari administration. These results may also be an artifact of how samples were grouped in the analysis. The chronology of the Nazca Valley samples groups them with the MH samples. However, the Nazca Valley specimens are relatively dated which introduced the possibility of error in the study. Also, it has been noted that the Wari withdrew from coastal regions, including the Nazca River valley, earlier than in the highlands. In terms of social
interaction and its impact on population genetic structure, the Nazca valley samples may be more accurately grouped with the LIP samples. Clearly, the Nasca case warrants further study.
In the north-central highlands the Hualcayan population was an outlier. The evidence for Wari presence in this region is much obvious than for other regions sampled like the south- central highlands. The results probably reflect isolation by distance, but there is also linguistic evidence for isolation of this population. The LIP sample from this region, Marcajirca, also was an outlier. The results concerning these samples are consistent with similar studies of
populations in this region. As is the case with the Nasca population, the north-central highlands groups also deserver further study.
8.1.2 Conclusions drawn from the Late Intermediate Period samples
Overall FST values do not indicate a decrease in the rate of gene flow after the collapse of
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relative rates of gene flow. Other studies have not been able to demonstrate a complete
population replacement in the Ayacucho basin (Kemp et al., 2009). If there was not a different group inhabiting Huari after the demise of the empire, then these results indicate that the collapse of the empire had a dramatic impact on population genetic structure in this region. In the
absence of any local political autonomous structure a dramatic change in social interaction and organization would be expected. Presently the samples available do not provide for a fine resolution akin to what was found nearby in Andahuaylas. It is also likely that the heartland populations “felt” the effects of the end of the Wari horizon more acutely than other regional populations. A better understanding of the impact of the Wari collapse on the population genetic structure of Ayacucho is certainly in need of further study.
Close to the Wari heartland in the south-central highlands the Andahuaylas samples seemed less affected by the collapse of the Wari with respect to rates of gene flow. Patterns in biological affinities between samples in this subset were also consistent with archaeological and ethnohistorical data. These results were exciting in that they support the hypothesis that kinship structure, especially the moiety which is related to the dualism of Andean cosmology, does have an immense time depth. The results also reinforce the importance of considering multiple lines of evidence when interpreting biological distance results. These patterns could not have been as fully interpreted with only archaeological, or only ethnohistoric data. The Andahuaylas dataset is still being enriched and potential for further analysis will be discussed in the Future Directions
of Research section.