UC Berkeley

Utilizing skeletal remains from an urban, colonial hospital in Central Mexico, this dissertation strives to illustrate how an examination of the bodies from archaeological contexts can shed light on the activities of everyday life in the past. While other archaeological material can tell us about the tools used to perform activities, we do not always have accurate information about who was doing what, when, and for how long. If not careful, scholars can fall into the trap of preconceived notions of a gendered division of labor that may or may not accurately portray how daily life activities were organized in other times and spaces. This issue is complicated by historical documents from the Spanish Colonial Period in the Americas, which were often written by European men and with specific administrative agendas. Similarly, the examination of gendered objects within archaeological explorations of Colonial Mexico are fraught with cyclical reasoning that stem from methodological issues within the subfield of bioarchaeology. Skeletal remains provide an exceptional opportunity to examine the actual bodies of individuals that accomplished day-to-day tasks. Yet, rather than simply relying on binary sex categories derived from skeletal features to discern gendered patterns of labor, I instead examine groupings of individuals that are derived from similar kinds of biomechanical stress. Combining the social theories of embodiment and materiality with biological understandings of bone remodeling and biomechanics, the bioarchaeological analyses used in this research illustrate how the social and biological interact to create unique individual bodies that literally become chronicles of the amount and kind of activities performed during life. These changes better illustrate the organization of labor that actually occurred rather than arbitrarily creating groups of individuals based on modern conceptions of sex/gender that cannot always be ascertained from the skeleton and may not have even existed in societies in the past.

The specific historical focus of my research is on the urban colonial experience in Central Mexico. The skeletal collection utilized in this study was recovered from the remains of the Hospital Real San José de los Naturales (HSJN), established in 1553 as the first royally sponsored hospital to care for the indigenous population in the Spanish colonies. Three non-invasive bioarchaeological analyses are used to discern subtle material changes to the bone tissue. Macroscopic analysis of entheseal changes interprets the areas of insertion for muscles on long bones that change with biomechanical stress from repetitive movements commonly used in everyday life. Next, metacarpal radiogrammetry examines the amount of cortical bone of the second metacarpal bone of the hand and provides a rough estimation of the amount of bone remodeling that occurred throughout adulthood for each individual as well as the trends in the population as a whole. Finally, cross-sectional geometry utilizes computed tomography images of the transverse plane of long bones (humerus and femur) to analyze the amount of cortical bone as well as its distribution around the central axis of the long bone. This geometric analysis provides not only an understanding of the amount of bone, but its overall strength and rigidity in response to biomechanical stress. The combination of various bioarchaeological analyses provides a richer understanding of the numerous ways in which the stress of daily activity becomes literally incorporated into bone. Furthermore, none of these methodologies are intrinsically tied to the traditional methodology of sexing skeletons and therefore is free from many of the interpretive issues that result from simplistic categorizations of individuals.

Most bioarchaeological data analyzes these data separated according to age or sex groups, but this practice is based on the assumption that a difference should be present between these variable. In this study, differences in the amount of muscle usage is found when following this method of preliminary division by age and sex, but differences in the kind of muscle usage is less clear. This could be the result of a significant overlap in the kinds of biomechanical stress received over the life course and between males and females. Instead, I used an exploratory data analysis software program and statistical cluster analysis, to identify groups of individuals with similar kinds of bony changes. None of these cluster groups consisted of solely males or solely females, supporting the notion that a preliminary division may obscure other patterns of biomechanical stress.

The cluster analyses help to do two things overall - isolate small groups of individuals on the extremes with a lot of bone growth or very little bone growth so that other averages are not skewed; and isolate groups of individuals who experienced unique kinds of movement. Additionally, these analyses are able to isolate variation that exists in terms of movement within age or sex groups. Sharing a sex/gender identity does not automatically mean that you will have the same opportunities available to you. This is an especially important factor to remember for this skeletal population, since other identities such as geographical origin or migration status created drastic differences in activity.

For the lower limb, the ability to isolate unique kinds of movement proved to be the most useful aspect of this different interpretive approach. When examining the data by age or sex groups, all individuals showed signs of walking on two feet (leg extension, lower leg flexion and extension, and plantar flexion) with only slight differences in the amount of stress. One of the groups derived from the cluster analysis, however, indicated that in addition to the movements associated with walking they also had a higher amount of stress from leg adduction (moving the leg toward the midline of the body). During this time period, the Spanish introduced new techniques for creating pottery using a potter's wheel with a lower kick wheel to create momentum. It is possible that this isolated group of individuals may have experienced this unique kind of biomechanical stress as a result of such a unique labor opportunity.

For the upper limb, the cluster analysis was useful for isolating groups of individuals with different kinds of movement, but also for showing variation in the amount of stress within sex groups. The data, when preliminarily divided according to age and sex, showed slight increases in the amount of stress across the life course and high average scores for males than females; however, differences in kind of biomechanical stress was less clear. The groups derived from cluster analysis for entheseal changes helped to separate groups of individuals with more whole arm movements (arm extension, shoulder rotation, and arm abduction) and a group of individuals with more precise forearm movements (forearm supination, forearm flexion, and hand/wrist control). The individuals in this last group are both males and females, which is why it may have been difficult to discern this difference with the data preliminarily divided. Another important distinction found was different levels of activity among individuals that performed these whole arm movements and that also caused an increase in the amount and distribution of the cortical bone among the males in the population. Only indigenous males were obligated to participate in the different tribute labor systems during this colonial time and it is possible that the cluster groups help to isolate this subset of the male population that performed more strenuous manual labor.

Interpretation from a perspective of embodied subjectivities acknowledges that many different aspects of identities controlled the kinds of labor opportunities available to individuals in urban New Spain. Individuals who performed similar kinds of work on a day-to-day basis will have similar kinds of responses to these biomechanical stresses and cluster analysis illustrates actual distinctions in the way individuals were using their bodies that then became incorporated into the skeleton. If the data are divided from the beginning of analysis then our interpretations are inventing differences that may or not actually exist. Rather, biological data related to categorical aspects of identity should be added into interpretations only after groups of individuals with similar kinds of bone changes have been identified, in order to avoid assumptions about labor organization based on modern conceptions, historical written documents, or other archaeological data. The complex intersection of gender, geographical origin, age, and migration status during the colonial period likely influenced the creation of these variable groups of individuals with unique biomechanical stress.

Despite the unique historical moment that brings these varied populations together, bioarchaeological analyses of other times and places should also attempt to analyze the data from a perspective of embodied subjects. This means that patterns of organization should be discerned from the bone functional adaptation data first. The groups of individuals identified will then represent people who experienced similar kinds of biomechanical stress that later became materially incorporated into their bodies. Interpretation of these patterns should include other biological variables, like age and sex, but only after divisions by biomechanical stress. Preliminary divisions only test if our assumptions about how labor should be organized actually exist, rather then help to interpret actual patterns of difference.