Ancient DNA from the Schild site in Illinois: Implications for the Mississippian transition in the Lower Illinois River Valley.

Archaeologists have long debated whether rapid cultural change in the archaeological record is due to in situ developments, migration of a new group into the region, or the spread of new cultural practices into an area through existing social networks, with the local peoples adopting and adapting practices from elsewhere as they see fit (acculturation). Researchers have suggested each of these explanations for the major cultural transition that occurred at the beginning of the Mississippian period (AD 1050) across eastern North America. In this study, we used ancient DNA to test competing hypotheses of migration and acculturation for the culture change that occurred between the Late Woodland (AD 400-1050) and Mississippian (AD 1050-1500) periods in the Lower Illinois River Valley. We obtained sequences of the first hypervariable segment of the mitochondrial genome (mtDNA) from 39 individuals (17 Late Woodland, 22 Mississippian) interred in the Schild cemetery in western Illinois, and compared these lineages to ancient mtDNA lineages present at other sites in the region. Computer simulations were used to test a null hypothesis of population continuity from Late Woodland to Mississippian times at the Schild site and to investigate the possibility of gene flow from elsewhere in the region. Our results suggest that the Late Woodland to Mississippian cultural transition at Schild was not due to an influx of people from elsewhere. Instead, it is more likely that the transition to Mississippian cultural practices at this site was due to a process of acculturation.

Introduction: Scientific rigor in paleopathology.

This introductory chapter to the Special Issue on "Scientific Rigor in Paleopathology" serves to orient and introduce the chapters that follow through a detailed consideration of paleopathology as a 21st century intellectual field. In this vein, we first make the significant point that paleopathology is a profoundly interdisciplinary endeavor, encompassing aspects of the biomedical science, the humanities, and the social sciences. Thus, we suggest that no one practitioner can personally command the range of skills necessary for a 21st century paleopathologist. To maintain rigor in differential diagnosis, we emphasize collaborations and consider key concepts that illustrate the basic knowledge from each of these fields that any paleopathologist should command. We then address the manner in which disease diagnosis should proceed as a scientific endeavor. To illustrate scientific rigor in differential diagnosis, we present two case studies drawn from 1970s contributions by Cook and by Buikstra. Finally, we introduce Chapters 2-6, which address differential diagnosis in contexts ranging from specific conditions (scurvy, trepanation) to broader field-wide considerations (paleoparasitology, historical paleopathology, imaging, animal paleopathology).