Identifying Changepoints in Population Size through Radiocarbon Determinations

通过放射性碳测定确定人口规模的变化点

• 批准号: EP/X032906/1
• 负责人: Timothy John Heaton
• 金额: $ 10.21万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX032906%2F1
• 关键词: Identifying; Changepoints; Population; Size; through

An 8-month project to develop, and test, novel statistical tools that will enable environmental, and archaeological, scientists to accurately identify changes in the past size of populations from samples dated via radiocarbon. Studying changes in patterns of occupation is key to understanding our responses to past environmental and societal changes, and to forecasting our resilience to potential future climate change. It is essential to provide a statistically-rigorous alternative to replace some of the incoherent approaches currently used.A frequently-used archaeological approach to estimating changes in the size of a population is to consider how the number of samples relating to that population (e.g., human/animal bones, or other evidence of occupation) varies over time. Time periods for which there are large numbers of samples are expected to correspond to a larger population being present; periods when fewer samples are found suggest a smaller population size. Such an approach can be applied to individual sites, or by collating samples across multiple sites. The reliability of such a "dates-as-data" approach is highly dependent upon our ability to estimate the calendar ages of the discoveries. When studying the last 55,000 years, the most common way to obtain the necessary dates is via radiocarbon. Unfortunately, the need to calibrate all radiocarbon determinations introduces considerable, and complex, uncertainties into the calendar ages of each of the samples. This uncertainty should be incorporated into later inference such as when using the density of the dates as a proxy for population size. However, it is well recognised that the techniques currently used by the radiocarbon community fail to do so fully. This limits the reliability of the inference they provide. New statistically-rigorous tools are required. This project will provide them. We will develop an integrated Bayesian framework that is able to jointly calibrate the radiocarbon determinations belonging to a set of samples, and to identify if there are statistically-significant changes in the rate at which the samples arise. We will demonstrate our approach on a range of geoscientifically-interesting questions including the expansion of humans into the Yukon and Alaska in the late Pleistocene and early Holocene. We will aim to investigate both the timings of such migrations in comparison with the climatic changes known to have occurred during this period, and to study the potential interactions between humans and other megafauna in the region. In addition to developing and publishing the statistical framework, we will also work to ensure our work is of maximum benefit to the target radiocarbon user community. We will disseminate our research through provision of usable and easily-accessible software; and a user-guide providing illustrative cases studies and worked examples, that is appropriately written for the target archaeological and environmental science community.

这是一个为期8个月的项目，旨在开发和测试新的统计工具，使环境和考古科学家能够通过放射性碳测定样本准确地确定过去人口规模的变化。研究职业模式的变化是理解我们对过去环境和社会变化的反应，以及预测我们对未来潜在气候变化的适应能力的关键。必须提供一种统计上严格的替代方法，以取代目前使用的一些不连贯的方法。一种常用的考古方法来估计人口规模的变化是考虑与该人口有关的样本数量（例如，人类/动物骨骼或其他占领证据）如何随时间变化。预计存在大量样本的时间段对应于存在较大人口的时间段；当发现的样本较少时，表明人口规模较小。这种方法可以应用于单个站点，也可以跨多个站点整理样本。这种“日期即数据”方法的可靠性在很大程度上取决于我们估计这些发现的日历年龄的能力。在研究过去55000年的历史时，最常用的方法是通过放射性碳测定。不幸的是，校准所有放射性碳测定的需要给每个样品的日历年龄带来了相当大的、复杂的不确定性。这种不确定性应纳入以后的推断，例如当使用日期密度作为人口规模的代理时。然而，众所周知，放射性碳界目前使用的技术并不能完全做到这一点。这限制了它们提供的推断的可靠性。需要新的统计严谨的工具。这个项目将提供这些。我们将开发一个集成的贝叶斯框架，该框架能够联合校准属于一组样品的放射性碳测定，并确定样品出现的速率是否存在统计上显著的变化。我们将在一系列地球科学上有趣的问题上展示我们的方法，包括在更新世晚期和全新世早期人类向育空地区和阿拉斯加的扩张。我们的目标是将这种迁徙的时间与这一时期已知发生的气候变化进行比较，并研究该地区人类与其他巨型动物之间潜在的相互作用。除了制定和发布统计框架外，我们还将努力确保我们的工作对目标放射性碳用户群体有最大的好处。我们会透过提供可用及易于使用的软件，传播我们的研究成果；还有一份用户指南，提供了说明性的案例研究和工作实例，这是为目标考古和环境科学界编写的。

项目成果

Atmospheric radiocarbon levels were highly variable during the last deglaciation

• DOI: 10.1038/s43247-023-00929-9
• 发表时间: 2023-07
• 期刊: Communications Earth & Environment
• 作者: S. Talamo;M. Friedrich;F. Adolphi;B. Kromer;T. Heaton;Silvia Cercatillo;R. Muscheler;Dragana Paleček;Enrico Pelloni;Laura Tassoni;V. Toniello;L. Wacker