People, Plants, and Landscapes in Prehistoric Ecuador: A Look at the Causes and Consequences of Agriculture

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With National Science Foundation support, Deborah M. Pearsall and colleagues will undertake the second phase of a project to study the antiquity of maize in prehistoric coastal Ecuador, and the interplay of environmental and social factors for the emergence and development of agricultural societies. Using environmental coring, the project will study changes in vegetation, land-use practices, and food-ways associated with the emergence of agriculture.Southwestern coastal Guayas Province has been proposed as a center of domestication of cotton, lima bean, squash, and jackbean, and is part of the region in which chili pepper, cocoyam, lleren, arrowroot, Canna, and sweet potato originated. Many of these crops appear during the Preceramic (9800-6700 BP) and Early Formative (5500-3500 BP) periods. Evidence that maize was introduced late in the Preceramic, and was present at the Early Formative Real Alto site, constitutes one of the earliest dates for this crop in South America. It is difficult to assess the importance of maize, and the role it played in the emergence of complex societies on the coast, on the basis of available data, however. The transformation of societies from fisher-gatherers to agriculturalists impacts local environments significantly, for example, when farmers clear forests for fields. Hypotheses concerning the causes and consequences of agriculture can therefore be tested with ancient environmental records, by evaluating the timing, sequence, and nature of changes in subsistence practices vis a vis changes in the natural environment (vegetation responses to climate change) and the social/political environment (changes in settlement pattern, population, and social and political complexity). In the first phase of the project, well-dated environmental records were recovered by coring in lagoon environments in three key localities. Microfossils (pollen and phytoliths) of past vegetation and crops were preserved in the cores. In the second phase of the project, two new locations will be cored, and all sediments will be analyzed for microfossil evidence of past vegetation and crops, and elemental and isotopic signatures of past climate. The intellectual merit of the research lies in its contribution to understanding the causes and consequences of agriculture. The project will provide a case study of agricultural evolution in a lowland, dry tropical forest region that explores the roles of environmental and social factors in the emergence of agriculture. The research team also hopes to document how local populations adapted to the new habitats and resources of the post-glacial period.Dry tropical forests, such as those that once characterized southwestern Guayas, are among the most endangered ecosystems in the New World because of the advantages they hold for modern agriculture. Evidence is accumulating that such habitats were also the focus of prehistoric agriculture, and home to many crop plants. Was agriculture sustainable in dry tropical forests prehistorically? The broader impacts of the study will be insights gained into the nature of human impact on forests through time, and practices that permitted populations to use these habitats for thousands of years. These findings may have application to the contemporary issue of sustainable uses of tropical forests.