Under the guidance of Dr. Margaret Schoeninger, Andrew Somerville will reconstruct past environmental conditions across a transect of four North American archaeological sites in the United States and Mexico. This will be accomplished through the application of stable isotope analysis to rabbit and hare (leporid) bones (n=347). The selected archaeological site locations geographically span the arid regions between Central Mexico and the Southwest United States, and temporally cover the period of AD 200-1200. Isotopic ratios of carbon nitrogen and oxygen in mammalian bone are influenced by environmental factors such as local botanical composition, average precipitation, and relative humidity, and thus analysis of ancient specimens enables the reconstruction of past landscapes. In addition to archaeological samples, Mr. Somerville will analyze a large collection of modern leporid bones selected from museum collections in order to provide baseline data to aid in the interpretation of isotopic values of pre-Hispanic leporids. Environmental data from each archaeological location will permit investigations of the dynamic relationship between environment and society over long stretches of time.
This project focuses on marginal arid landscape of north of the Meosoamerican core as cultural historical models for the rise and decline of socio-political complexity in the region have frequently implicated climatic change as a driving factor. During the 6th century AD, complex Mesoamerican societies expanded into the desert regions north of Central Mexico, particularly the modern states of Zacatecas and Durango. Despite four centuries of occupation, most complex polities of the arid north, such as La Quemada and Alta Vista, were abandoned at about AD 900. These broad patterns of development and decline led scholars to argue that favorable environmental conditions permitted the expansion of Mesoamerican civilization and that severe and prolonged droughts brought about its eventual retraction. Isotopic data generated from this project will either provide the first empirical support for prominent role of environmental factors of the expansion and contraction of Mesoamerica, or will provide evidence contrary this long-standing assumption.
More generally, this dissertation research will increase our understanding of the role of the environment during the development and decline of complex societies during the Late Holocene. Reconstructing the environmental conditions present during the initial years of selected sites will address models concerning the relationship between ecological factors and incipient socioeconomic development, particularly the notion that agriculturally productive zones provided powerful advantages to newly developing economies. Knowing the environmental conditions leading up to political collapse or abandonment at each site will provide opportunities to study social-environmental patterns present during periods of rapid social transformation and to identify social strategies which led to systemic vulnerability or resiliency. Ultimately, this dissertation seeks patterns, trends, and lessons from past social-environmental interactions that may better contextualize our modern environmental concerns.
