Mortuary Tradition and Social Transformation during the Late Intermediate Period (A.D. 1100-1450): A Bioarchaeological Analysis of Above-Ground Burials in the Colca Valley, Peru

Abstract

This dissertation investigates how new forms of burial involving the placement of mummies in above-ground sepulchers impacted, and were shaped by, processes of identity formation and political change during the Late Intermediate Period in Peru (A.D. 1100-1450), a time of widespread conflict culminating in Inka conquest. Did mortuary practices intensify political fragmentation by reifying group boundaries, or did they mitigate social turmoil and resource risk by promoting inter-group alliance? This question is addressed through the analysis of human skeletal remains from the Colca Valley. Specifically, this dissertation examines: 1) patterns of cranial vault modification (CVM) to explore if mortuary treatment reinforced social differences marked on the body; 2) heritable traits on the human cranium to test if cemeteries were organized by biological kinship and evaluate scenarios of boundary maintenance via endogamy or alliance formation via inter-marriage; and 3) stable carbon and nitrogen isotope ratios from bone collagen to reconstruct diet and shed light on subsistence differentiation and resource access. Fifteen radiocarbon dates from human bone and mortar used in tomb construction facilitate the comparison of these data before and after the onset of Inka state formation.

Results show that a transformation in social identity was articulated through, rather than apart from, longstanding mortuary traditions. After A.D. 1300, the proportion of the skeletal population exhibiting CVM dramatically increased, signaling an emergent ethnic identity, perhaps in response to encroaching Inka influence. However, modified and unmodified individuals were buried in the same sepulchers, and biodistance analysis of cranial non-metric traits suggests they actually belonged to the same familial groups organized around shared ancestry and burial customs. Stable carbon and nitrogen isotope ratios do not reveal marked differences in resource access or subsistence specialization between burial groups, but instead are consistent with a broadly encompassing subsistence economy oriented toward pastoralism. Notably, modified individuals exhibit slightly but significantly greater heterogeneity in dietary protein intake, possibly indicative of increased mobility between ecological and subsistence zones. By integrating multiple lines of bioarchaeological data, this research demonstrates empirically how social difference and intra-community cohesion intersect in daily life and in the ritual practices surrounding death.