Doctoral Dissertation Research: An Isotopic Assessment of Late Prehistoric Interregional Warfare in the Southcentral US

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There is a great need to develop better methods to identify and quantify warfare when it occurs without accompanying written documentation, and to consider alternative explanations of data. The study of isotopes preserved in human skeletal remains provide a valuable means to identify the geographic origins of individuals or groups buried in archeological contexts suggesting warfare, offering evidence that can corroborate other archaeological and biological indicators (fortifications, village destruction, traumatic skeletal injury, etc.). Even so, refinement of isotopic methods is required to improve the confidence of results. Lead (Pb) is a toxic trace metal that affects the health of biological organisms, but its composition can also indicate from where an individual originates. Pb isotopes preserved in human tooth enamel provide a signature, via food chain pathways, of the geographic area in which that individual was born and grew up. This study will establish and demonstrate a new method for biological sourcing, the biological available Pb method, which compares the Pb isotopes of prehistoric human and non-migratory animal populations to determine if humans found in the archaeological record of one area are local or actually came from another region. This will aid researchers who commonly question whether particular burials or mortuary treatments, such as isolated skulls and mandibles, reflect special burial treatment of honored ancestors or the disposal of dismembered enemies from other regions. This study will test if late prehistoric Caddo communities in southwest Arkansas were committing large-scale acts of violence against neighboring regions. Concurrent archeological evidence of increased violence in the Southern Plains and the Eastern Woodlands may reflect increasing tensions between regions. Alternatively, unusual burial treatments often attributed to warfare might indicate alternative practices involving transport of partial skeletal remains for special burial at important regional centers. This study also serves the practical purpose of determining cultural affiliation for the purposes of Native American Graves Protection and Repatriation Act compliance and to inform and encourage feedback from descendant communities including the Caddo Nation of Oklahoma. The study also has practical forensic applications for determining points of geographic origin for human skeletal material recovered from multiple present day/recent contexts.Mr. Samuelsen, under the supervision of Dr. George Sabo III, will employ Pb and strontium (Sr) isotope analysis to evaluate early lifetime locations for the remains of 352 individuals represented in a skull-and-mandible cemetery (A.D. 1253-1399) at the Crenshaw site in southwest Arkansas, as part of his dissertation research. This will be accomplished through the creation of a comparative multi-state map of biologically available Pb/Sr isotopic ratios from states surrounding Arkansas. This map will be compared to Pb/Sr isotopic ratios from the human and animal remains from Crenshaw and other southwest Arkansas sites. High resolution Pb and Sr isotopes will be obtained using a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) at the University of Arkansas. The resulting data, whether indicating local or foreign origin, will illustrate how biological Pb isotopes can be analyzed, how they can reveal the purpose behind specialized burial treatments, and demonstrate how isotopes like Pb and Sr can help evaluate the prevalence and extent of many ancient cultural practices including interregional warfare and specialized mortuary practice.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.