Populating a Radiocarbon Database of North America, Phase III

放射性碳定年法为考古学家提供了少于45000年的有机材料（尤其是壁炉里的木炭）的年代。这是北美考古学家使用的主要方法，为了从考古遗址获得数千个这样的日期，联邦政府和其他机构已经投入了数百万美元的资金。世界各地的研究人员现在利用放射性碳年代随时间变化的丰度作为一种重建人口的方法，从而提供了人类历史的重要组成部分：人口在何时何地上升和下降？有多快?人口变化与环境变化、技术创新、人口密度、生存、战争、移民、社会和政治组织有何关系？该项目已经汇编了美国西部11个州（约42,000）和12个平原/中部州（约14,000）的数据；现在，它将继续收集美国其余三分之一的东部地区的数据。研究人员不仅需要编译日期本身，而且还需要“清理”数据库的相关上下文信息，以创建对其特定研究问题有用的样本。这些数据将通过加拿大考古放射性碳数据库公开和免费提供，这是一个大型和不断增长的国际放射性碳数据库。它将为研究人员提供一个有用的工具来调查包括考古学、古生物学和遗传学在内的几个学科的研究问题，并帮助北美考古学走向下一个前沿——“大数据”，因为考古学的优势在于它能够根据大范围的空间和时间的数据模式来检验假设。这个项目的重点是史前人口增长率和下降率的问题。它已经发现，农业人口的长期增长率与早期狩猎和采集人口的增长率相同，这意味着人口的快速增长只是现代人类生活的一个特征，是19世纪食品生产、贸易和医学知识方面技术进步的产物。该项目还发现了公元1500年前美洲原住民人口的下降，其原因正在调查中，并结合国际数据，在过去的1万年中，全球人口趋势具有显著的同向性。为了实现这一目标，该项目还在研究对大量放射性碳测年样本进行统计分析的“最佳实践”。假设单位时间内约会次数的上升和下降与人口数量的上升和下降类似。有理由保持谨慎，因为有几个变量可能会改变这种关系，例如，研究偏差，由于保存而导致的日期随时间的系统性损失，以及用于将放射性碳年龄转换为熟悉日历日期的标准程序的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.