Doctoral Dissertation Improvement Award: Phytolith Analysis in Determination of Environmental Change

This project investigates the relationship between environment and the shift in hominin stone tool technology and behavior occurring during the Late Middle Paleolithic LMP ~60–40 ka) and Early Upper Paleolithic (EUP ~46—30 ka). This shift is associated with the territorial expansion of Homo sapiens and the gradual disappearance of Homo neanderthalensis. The timing and nature of this transition differs across geographic regions. Why and how it occurred remains one of the major questions in late Paleolithic archaeology. In this study, microscopic plant remains from three geographically and environmentally distinct sites spanning the LMP—EUP are investigated. Comparing the environment to the technology and geographical movement of Neanderthals and modern humans sheds light on the degree to which changes in the local landscape influenced changes in behavior. The methods utilized here are applicable to late Paleolithic archaeology providing researchers a straightforward tool to investigate the same questions. During the last ice age, the region acted as a climatic refuge for plants, and possibly also Neanderthals and modern humans. Today, the region is a biodiversity hotspot with over 6000 species of plants. Understanding past local environment change as a result of climate change can therefore be important to understand not only behavior of earlier hominins, but also how the environment responds to future climate change. Archaeology is particularly well placed to study the influence of climate on local environments owing to the extended periods of time studied. This project uses phytolith analysis to recreate past environments. Phytoliths are silica imprints of plant cells, and therefore direct evidence of the plants present at the time. The use of phytoliths for environmental recreation is well established and can be applied in virtually any place where there are or have been plants. Previously, regional modern soil samples were taken from different environments, and analyzed to create vegetation fingerprints, associating phytolith assemblages with particular vegetation types. The result of this work provides a proxy, showing what type of phytoliths can be expected in a particular environment. Through statistical analysis of the archaeological phytolith assemblages in conjunction with the modern data, a detailed recreation of past environments are produced. These results are analyzed alongside archaeological data of hominin behavior acquired over the last two decades by different research groups in the region. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.