When Spanish explorers first arrived in the region later known as the southeastern United States in the early 16th century, they encountered complex, chiefdom level societies in many areas. These societies, with populations commonly numbering in the thousands and occasionally tens of thousands, were characterized by hereditary inequality of individuals and groups, monumental architecture, elaborate ceremonialism, and were engaged in constant warfare with one another. While state societies like those present in western South America and Mesoamerica were not found in the Southeast, most scholars believe they would have eventually emerged within the region. Indeed, some believe that a state did emerge briefly at Cahokia in the central Mississippi Valley around ca. AD 1050. The contact era societies the early European explorers saw, however, represented only the final chapter in a long record dating back thousands of years. Seemingly complex societies characterized by formal cemeteries and elaborate ceremonialism were present in the region as far back as the terminal Pleistocene some 12.000 years ago, as represented by the Dalton culture of the central Mississippi Valley, while the construction of massive mound complexes of earth and shell appears in many areas in the later Mid-Holocene era, after ca. 7000 cal yr BP. Complex societies thus persisted for thousands of years in the Southeast, with hunting and gathering providing the means of subsistence for much of this interval. Agricultural food production only became important in the final two millennia before contact, long after complex societies were widely established. / A principios del siglo XVI, cuando los exploradores españoles llegaron por primera vez a la región más tarde conocida como el Sureste de los Estados Unidos, encontraron sociedades complejas correspondientes al ámbito de las jefaturas en muchas áreas. Este tipo de organizaciones, con poblaciones que alcanzaban los miles y, ocasionalmente, las decenas de miles de personas, se caracterizaban por una desigualdad hereditaria de individuos y grupos, arquitectura monumental, ceremonialismo elaborado y constantes guerras entre ellas. Si bien sociedades del tipo que existieron en la parte occidental de Sudamérica y en Mesoamérica no se han encontrado en el Sureste, diversos estudiosos piensan que, en algún momento, esto pudo haber ocurrido en la región. Ciertamente, se sostiene que, si bien de manera breve, en Cahokia, en el valle central del Mississippi, surgió un Estado alrededor de 1050 d.C. Sin embargo, esta época particular, en que las comunidades entablaban contacto y que vieron los exploradores europeos tempranos, representaba solo el capítulo final de un largo registro que retrocede miles de años en el tiempo. Al parecer, las sociedades complejas caracterizadas por cementerios formales y un elaborado ceremonialismo existían ya hacia fines del Pleistoceno, alrededor de 12.000 a.p., tal como lo representa la cultura Dalton, del valle central del Mississippi, mientras que la construcción de complejos de montículos masivos de tierra y conchas aparece en muchas áreas en la parte tardía del Holoceno Medio, hacia alrededor de 7000 A.P. De esta manera, las sociedades complejas persistieron por miles de años en el Sureste y, en gran parte de este intervalo, sus medios de subsistencia fueron la caza y la recolección. La producción agrícola de alimentos solo cobró importancia en los dos últimos milenios antes del contacto con los europeos, mucho después de que este tipo de agrupaciones estuvieran ampliamente establecidas.

This thesis assesses climate change during the Hypsithermal Climatic Interval through the analysis of freshwater mussel remains from archaeological sites in Eastern North America. Modern climate data was used as a model to test the mosaic consequences of climate change. Freshwater mussels: can be used as indicators of precipitation by examining changes in overall size through time: larger mussels are found in larger streams, while smaller mussels are found in smaller streams. This study combines morphometric and isotopic data from archaeological freshwater mussels at Modoc Rock Shelter, Watson Brake, Plum Creek, Owens site, and Landerneau mounds to assess past climatic conditions. At Modoc Rock Shelter, oxygen isotopic data corroborate morphometric data and show that climate was fluctuating with a period of stability at the onset of the Hypsithermal. The oxygen isotopic data sets from the Louisiana sites show that the mid-Holocene was much warmer than the late-Holocene.