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.

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从通过放射性碳测年的样本中准确地识别过去人口规模的变化。研究职业模式的变化，对于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，是关键。必须提供一种统计上严谨的替代方法来取代目前使用的一些不连贯的方法。一种经常使用的考古学方法来估计种群规模的变化，是考虑与该种群有关的样本数量(例如，人/动物骨骼或其他占领证据)如何随时间变化。样本数量多的时间段预计对应于存在较大的人口；发现较少样本的时间段意味着人口规模较小。这种方法可以应用于单个站点，也可以通过比较多个站点的样本来实现。这种“日期即数据”的方法的可靠性高度依赖于我们估计这些发现的日历年龄的能力。在研究过去55,000年的时间时，最常见的获得必要年代的方法是通过放射性碳。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多和复杂的不确定因素。这种不确定性应纳入以后的推论中，例如当使用日期密度作为人口数量的替代时。然而，人们很好地认识到，放射性碳界目前使用的技术没有完全做到这一点。这限制了他们提供的推论的可靠性。需要新的严格的统计工具。这个项目将为他们提供。我们将开发一个综合贝叶斯框架，能够联合校准属于一组样本的放射性碳测定，并确定样本出现的速度是否有统计上的重大变化。我们将展示我们在一系列地学上有趣的问题上的方法，包括在更新世晚期和全新世早期人类向育空和阿拉斯加扩张的问题。我们的目标是将这种迁徙的时间与已知的在此期间发生的气候变化进行比较，并研究人类与该地区其他大型动物之间的潜在相互作用。除了制定和公布统计框架外，我们还将努力确保我们的工作最大限度地惠及目标放射性碳用户群体。我们将通过提供可用和易于获取的软件来传播我们的研究；以及一份用户指南，提供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适当编写的。

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