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Abstract
This dissertation research examines the interplay between prehistoric population dynamics and paleoenvironment, and the extent to which these factors influenced culture change over the last 3000 years on the western High Plains of Colorado. The population dynamics of prehistoric hunter-gatherers in eastern Colorado were estimated using several proxies, including the summed probability distribution of radiocarbon ages from archaeological sites in eastern Colorado. Understanding paleoenvironments of the western High Plains is critical to understanding prehistoric human adaptations to past climates and to predicting the magnitude and consequences of current climate change in this semi-arid region. Analyses of sediment cores from small fens (groundwater fed peatlands) on the High Plains indicate they contain high resolution (sub-decadal) paleoenvironmental records that extend into the middle Holocene (ca. 7800 BP). These "pocket fens" are small peatlands (25-2500 m2) sustained by springs fed by perched water tables. Fluctuations in the relative humification and organic content of peat from these features provide proxies for effective moisture and temperature, respectively. Due to the heterogeneity of the sediments contained within pocket fens, new methods of data analysis and display have been developed to compensate for sediment differences within and between fens. Data from pocket fens suggest that they contain sensitive records of relatively low magnitude climate fluctuations.
Well-dated, high-resolution records of paleoenvironment are important because they allow a more detailed examination of the complex relationship between climate, population and culture change. Here, these records from pocket fens not only document extended periods of high amplitude deviations in climate (such as drought) that could have influenced cultural adaptations, they also document periods of high temporal variability in proxy temperature and effective moisture that could have disrupted existing cultural systems. Periods of high temporal variability in climate would result in lower predictability of environment-dependent resources on an annual and decadal temporal scale, which in turn might have exceeded the inherent resiliency of cultural adaptations available within the knowledge base of these systems. Episodes of drought and high temporal variability in conjunction with periods of increasing population pressure correlate to periods of culture change during the past 3000 years in the archaeological record for eastern Colorado. This suggests that increased population and climate variability drove prehistoric culture change.
