Populating a Radiocarbon Database of North America, Phase III

点击翻译按钮获取中文摘要

Radiocarbon dating provides archaeologists with dates on organic materials (especially charcoal from hearths) that are less than 45,000 years old. It is the primary method that North American archaeologists use, and millions of dollars in federal and other funding has been spent in obtaining thousands of such dates from archaeological sites. Researchers around the world now use the changing abundance of radiocarbon dates over time as a way to reconstruct population over time, and thus to provide an important piece of human history: where and when did populations rise and decline? How fast? How does population change relate to environmental change, technological innovation, population density, subsistence, warfare, and emigration, social and political organization? This project has already compiled dates from the 11 western U.S. states (~42,000) and 12 Plains/Central states (~14,000); it will now move on to compile dates from the remaining eastern third of the US. It is not only the dates themselves that are compiled, but also associated contextual information that researchers need to "clean" the database to create a sample useful for their specific research questions. The data will become publicly and freely available through the Canadian Archaeological Radiocarbon Database, a large and growing international radiocarbon database. It will provide researchers with a useful tool to investigate research questions in several disciplines including archaeology, paleontology, and genetics, and help move North American archaeology toward its next frontier, "Big Data," since archaeology's strength is its ability to test hypotheses against patterns in data across vast reaches of space and time.This project focuses on the question of prehistoric rates of population growth and decline. It has already discovered that the long-term rates of growth of agricultural populations are the same as earlier hunting and gathering populations, and implies that rapid population growth is only a feature of modern human life, a product of nineteenth century technological advances in food production, trade, and medical knowledge. The project has also detected a pre-AD 1500 decline in Native American populations, the cause of which is under investigation and, combined with international data, remarkable synchronicity in global population trends of the past 10,000 years. To achieve its goal the project is also investigating the "best practices" of statistical analysis of large samples of radiocarbon dates. Rises and declines in the number of dates per unit time is assumed to track similar rises and declines in human population. There is reason to be cautious as several variables could modify this relationship, for example, research bias, the systematic loss of dates over time due to preservation, and the effects of the standard procedure used to convert radiocarbon ages in familiar calendar dates.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.