AN ABSTRACT OF THE DISSERTATION OF Sarah K. Muno for the Doctor of Philosophy degree in Anthropology, presented on September 26, 2018 at Southern Illinois University Carbondale. TITLE: LABOR AND SOCIAL IDENTITY IN ANCIENT PERU: A BIOARCHAEOLOGICAL PERSPECTIVE MAJOR PROFESSOR: Dr. Izumi Shimada This dissertation presents a bioarchaeological study of labor and social identity in coastal Peru during the Late Intermediate Period (900 – 1470 CE), using data from contemporaneous Middle Sicán (Sicán Precinct and El Brujo, north coast) and Ychsma (Pachacamac, central coast) mortuary contexts. I combine information about funerary treatment with skeletal evidence of trauma, degenerative joint disease, and muscle attachment site morphology (enthesial changes or EC) to test whether inferred commoners were “over-worked” relative to their elite counterparts, as often assumed based on western, Marxist notions of social class. Much of what has been inferred about socio-economic organization in coastal Peru during the Late Intermediate Period is modeled after the parcialidades described in early Spanish chronicles and colonial documents. In this system, occupation, social status, and ethnicity were intimately intertwined, with common fishers and farmers serving as the “productive base” for privileged members of society, including full-time artisans and their elite patrons. Archaeological evidence of elite sponsored large-scale labor projects, including specialized craft production, in pre-Hispanic coastal Peru accords well with the parcialidad model, but assumptions about the social identities of laborers often go untested. Human skeletal data offer a unique opportunity to redress this situation, providing information about life experience – including patterns of physical activity – that are not typically accessible with other kinds of archaeological data. Bioarchaeological studies of physical activity hold great promise for testing hypotheses about social identity and life experience in ancient societies, but they are not without some limitation. People who engage in strenuous physical activity tend to have more degenerative joint disease and enthesial changes than those who do not, but the precise mechanisms behind this are not well understood. Age and body size are known to influence these skeletal markers, although some researchers have suggested certain entheses may be less sensitive to size and thus more informative about activity, than others. In my sample, there were no discernible differences in skeletal trauma, degenerative joint disease, or ECs between elites and non-elites, or between males and females, when statistically controlling for the influence of age and/or size. These results do not support the hypotheses that non-elites were over-burdened by arduous labor tasks or that exemption from such tasks was part of the social privileges afforded to elites. Therefore, conventional perspectives that tend to conflate elite and non-elite identities with oppressor/oppressed or manager/laborer roles appear to have little relevance for characterizing the social dynamics of labor organization in Middle Sicán and Ychsma socities. My study supports, at least in part, previous research that argues some entheses are less prone to the influence of size than others, and may therefore be more reliable indicators of activity. In this sample, strong statistical correlations between EC scores, age, and size as determined from three humeral measurements were found for fibrous entheses, but humeral size did not correlate to scores for the fibrocartilaginous type. However, current uncertainties about the precise etiology of enthesial changes makes it difficult to interpret variation in EC scores with a high degree of certainty, and thus my study also highlights some of the drawbacks associated with using EC scores to infer patterns of activity. Experimental research to better understand how the timing, duration, and severity of muscle stress and strain influence enthesial development and technological innovations to quantify enthesial size and shape will be key to resolving these issues in the future.