Doctoral Dissertation Research Improvement Grant: Environmental Reconstruction of Mesoamerica's Northern Frontier through Stable Isotope Analysis of Leporid Bones

在玛格丽特·舍宁格博士的指导下，安德鲁·萨默维尔将在美国和墨西哥的四个北美考古遗址的横断面上重建过去的环境条件。这将通过对家兔和野兔（leporid）骨骼（n=347）进行稳定同位素分析来完成。选定的考古遗址地理位置横跨墨西哥中部和美国西南部之间的干旱地区，时间跨度为公元200-1200年。哺乳动物骨骼中的碳氮氧同位素比例受当地植物组成、平均降水和相对湿度等环境因素的影响，因此对古代标本的分析可以重建过去的景观。除了考古样本，萨默维尔先生还将分析从博物馆藏品中挑选的大量现代lepora骨骼，以提供基线数据，帮助解释前西班牙lepora的同位素值。从每个考古地点获得的环境数据将使我们能够研究长期以来环境与社会之间的动态关系。该项目关注中美洲核心北部的边缘干旱景观，作为该地区社会政治复杂性的兴衰的文化历史模型，气候变化经常被认为是一个驱动因素。公元6世纪，复杂的中美洲社会扩展到墨西哥中部北部的沙漠地区，特别是今天的萨卡特卡斯州和杜兰戈州。尽管被占领了四个世纪，但干旱的北部地区最复杂的政体，如La Quemada和Alta Vista，在公元900年左右被放弃了。这些广泛的发展和衰落模式使学者们认为，有利的环境条件允许中美洲文明的扩张，而严重和长期的干旱导致了它的最终退缩。该项目产生的同位素数据要么将首次提供经验支持，证明环境因素在中美洲的扩张和收缩中发挥了突出作用，要么将提供与这一长期假设相反的证据。更广泛地说，本文的研究将增加我们对环境在晚全新世复杂社会发展和衰落过程中的作用的理解。重建选定地点最初几年的环境条件将涉及生态因素与初期社会经济发展之间关系的模型，特别是农业生产区为新兴发展经济体提供强大优势的概念。了解每个地点导致政治崩溃或放弃的环境条件将为研究快速社会转型时期出现的社会环境模式提供机会，并确定导致系统脆弱性或弹性的社会战略。最后，本论文从过去的社会环境相互作用中寻求模式、趋势和教训，这些模式、趋势和教训可能会更好地为我们的现代环境问题提供背景。

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.