Stable isotopes as a tool for investigating changes in Holocene hunter-gatherer strategies along the northern California coast

在NSF的支持下，Ann Russell博士、Robert Bettinger博士和Michael Kennedy先生将使用稳定的氧和碳同位素（d18 O和d13 C），从加州海贻贝（Mytilus californianus）贝壳的边缘收集14 C年代的考古成分，以确定史前北方加州狩猎采集者在过去8600年中收获这种边缘海洋资源的季节。此外，他们还将评估贻贝收获的季节性与海洋条件变化之间的关系，这些变化是根据d18 O和d13 C的年度记录重建的。近年来，人们越来越关注狩猎采集者海洋适应的出现以及气候变化作为塑造文化反应的选择性力量的作用。加州南部和中部的主要文化变化，如边际资源的利用以及经济和社会政治复杂性的增加，可能是由于与海面温度（SST）和海洋生产力变化有关的资源压力而产生的。人们对北方加州海岸狩猎采集者进化的这些方面知之甚少。重建季节性觅食模式，以及北方加州沿着的上升流强度和海洋营养水平，将为理解这一地区海洋资源集约化的出现提供关键信息。（d18 O和d13 C）的含量提供了有关海洋环境条件（SST、营养水平和推断的海洋生产力）的重要信息。 初步结果证实了这一点，并建议同时使用终末边缘的d18 O和d13 C的方法（生长边缘）的贻贝californianus（加州海蚌）贝壳是决定收获季节的宝贵工具。狩猎采集者对边际海洋资源的利用程度如何（贝类）全年在北方加州，海洋气候在强化海洋觅食策略的发展中发挥了什么作用？为了解决这些问题，研究小组将从加州博德加湾附近的5个14 C-年代考古成分中产生贻贝壳方解石中d18 O和d13 C的三个季节性记录。这些剖面图将提供关于平均海洋环境条件的信息，以及占领时SST和d13 C季节变化的典型范围。除了这些长期记录外，研究人员还将从每个组件至少20个额外贝壳的终端边缘获得同位素数据，以确定收获季节。研究的一个重要方面将是继续进行现代校准/验证使用耦合d18 O和d13 C从壳终端边缘建立收获季节。利用这些研究的结果与其他考古数据相结合，研究小组将重建环境条件的变化和自8600 BP以来北方加州海上狩猎采集者的适应策略。这项研究将允许在过去的8600年的年度觅食强度的区域评估，并将提供一个更复杂的检查沿着北方加州海岸的海洋资源集约化比以前的研究已经提供。

With NSF support, Dr. Ann Russell, Dr. Robert Bettinger, and Mr. Michael Kennedy will use stable oxygen and carbon isotopes (d18O and d13C) at the edges of California sea mussel (Mytilus californianus) shells collected from 14C-dated archaeological components to determine the season in which prehistoric northern California hunter-gatherers harvested this marginal marine resource over the last 8600 years. In addition, they will evaluate the relationship between seasonality of the mussel harvest and changes in marine conditions reconstructed from annual records of d18O and d13C. In recent years, there has been increased focus on the emergence of hunter-gatherer maritime adaptations and the role of climate change as a selective force in shaping cultural responses. Major cultural changes in southern and central California, such as the use of marginal resources as well as increasing economic and sociopolitical complexity, may have developed from resource stress related to changes in sea-surface temperature (SST) and marine productivity. Little is known about these aspects of hunter-gatherer evolution along the coast of northern California. Reconstruction of seasonal foraging patterns, as well as upwelling intensity and marine nutrient levels along the coast of northern California will provide critical information for understanding the emergence of marine resource intensification in this region.Previous research has shown that the record of stable isotopes (d18O and d13C) in shell calcite of mollusk shells provides important information on marine environmental conditions (SST, nutrient levels, and inferred marine productivity). Preliminary results confirm this and suggest that the approach of using both d18O and d13C of the terminal margin (growing edge) of Mytilus californianus (California sea mussel) shells is a valuable tool for determining the season of harvest.How intensively did hunter-gatherers utilize marginal marine resources (shellfish) throughout the year in northern California, and what role did marine climate play in the development of intensified marine foraging strategies? To address these questions, the research team will generate three seasonal records of d18O and d13C in mussel shell calcite from five 14C-dated archaeological components near Bodega Bay, California. These profiles will provide information on average marine environmental conditions, as well as the typical range of seasonal variation of SST and d13C at the time of occupation. In addition to these long-term records, the researchers will obtain isotopic data from the terminal margins of at least 20 additional shells per component to determine the season of harvest. An important aspect of the research will be to continue a modern calibration/verification of the use of coupled d18O and d13C from shell terminal margins to establish the season of harvest. Using the results of these studies in conjunction with other archaeological data, the research team will reconstruct changes in environmental conditions and in the adaptive strategies of maritime hunter-gatherers of northern California since 8600 BP. This research will permit a regional evaluation of annual foraging intensity over the last ~8600 years, and will provide a far more sophisticated examination of marine resource intensification along the northern California coast than previous research has offered.