Middle-Holocene climates and human population densities in the Great Basin, western USA

Abstract

Much of western North America saw higher temperatures and lower precipitation during the middle Holocene. The Great Basin became much drier and warmer than it is today, causing major shifts in lake levels, treelines, plant community composition, and vertebrate distributions and abundances. To assess the impact of climate change on middle-Holocene human population densities in this region, we examine the frequency structures of radiocarbon-dated archaeological sites through time in three separate parts of the Great Basin: the Bonneville Basin, Fort Rock Basin, and western Lahontan Basin. The results of the analysis support the hypothesis that human population densities in many parts of the Great Basin dropped substantially in response to middle-Holocene climate change but also document that there were intervals during the middle Holocene in all three areas that appear to have been marked by temporary population increases. We hypothesize that these increases were associated with equally temporary increases in effective precipitation but, lacking adequate paleoenvironmental data, do not attempt to test this hypothesis.