The potential impact of the medieval climatic anomaly on human populations in the western Mojave Desert

Abstract

During the late 1980s and early 1990s, a model was proposed for changing settlement and subsistence patterns in the western Mojave Desert. The model posits that environmental fluctuations over the last 4,000 years were potential causal mechanisms for culture change in this region. One of these fluctuations was the environmental episode known as the Medieval Climatic Anomaly (MCA), a series of droughts that took place between about 1,200 and 650 B.P. The intent of this study was to determine whether apparent culture changes that began about 1,200 years ago in the western Mojave Desert are associated with the MCA. To accomplish this goal, a comparison of site and regional archaeological data sets was made in order to illuminate the effects proposed in this study. Examining numerous archaeological assemblages from sites in the western Mojave Desert that were excavated between the 1970s and 2000s, certain trends became apparent. As such, the data from this study support the hypothesis that various culture traits evident in the western Mojave Desert were either directly or indirectly impacted by the MCA, including an extreme subsistence focus on lagomorphs during the Rose Spring Period, expansion of the bow and arrow at about the same time, a severe reduction in obsidian use during the Late Prehistoric Period, human population increase during the Rose Spring Period and subsequent population decrease during the Late Prehistoric Period, and the Numic expansion. To what degree environmental episodes play a role in cultural transitions depends largely on the severity and duration of such episodes. The conclusion of this study is that the MCA was of sufficient severity and duration to have been a motivating factor for much of the culture change discussed in detail within this study.