Isotopic Methods for Sourcing Shell Beads in California

在加利福尼亚州采购贝壳珠的同位素方法

• 批准号: 1220048
• 负责人: Jelmer Eerkens
• 金额: $ 23.94万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1220048&HistoricalAwards=false
• 关键词: Isotopic; Methods; Sourcing; Shell; Beads

With support from the National Science Foundation, Drs. Jelmer Eerkens and Howard Spero will build on previous research to develop a robust method for tracing the geographic origin of ancient shell beads in Central California. The approach is based on stable isotope signatures preserved in the shells used to make beads. There is significant variation along the California Coast in seasonal water temperature, salinity, and upwelling of cold and nutrient-rich seawater. Together, these effects impart distinctive isotopic signatures to shells growing along different sections of the coast. When a shell is collected on the coast, turned into a bead, and traded inland, it retains the signature of where it originally grew in the calcium carbonate structure of its shell. When archaeologists recover shell artifacts far away from the coast, they can work backwards, from the artifact and through the isotopic signature, to determine where the shell originally grew.Archaeologists use these types of techniques to trace the movement of raw materials across the landscape and this allows them to reconstruct ancient trading and interaction networks. These trading networks, by extension, allow evaluation of how people adapted to their ever-changing social and natural environments. As new technologies were innovated and spread, demand for raw materials to support them also increased, and reliable access to raw materials that were not locally available would have been important. Archaeologists can trace the history and development of different technologies by examining where raw materials were procured, the style of artifacts produced, and how the two co-evolved over time. Although the specific case study to be examined here addresses ancient trade and exchange of marine shell artifacts in Central California, the approach can be applied to shell artifacts almost anywhere in the world.In California, indigenous peoples commonly made beads out of the purple olive shell, Olivella biplicata. At the time of contact, in the late 1700s, these shell beads were used in a manner akin to currency and they are ubiquitous in archaeological sites. An exact tally is not available, but over the last 100 years archaeologists have recovered well over a million Olivella beads from sites in Central California. Even the earliest sites in California, dating to over 10,000 years ago, have beads made out of Olivella biplicata. Why Native Californians selected this particular species is not known, but is something the proposed research may be able to address.This project will support one part-time post-doctoral researcher and one to two UC Davis undergraduate students, who will be trained in geochemical and archaeometric analysis. The data and resulting analysis will be shared with the Central California community through outreach efforts at UC Davis, including public displays at the UCD Anthropology Museum, programs with school children at Bodega Bay Marine Laboratory, and presentations at professional conferences.

在美国国家科学基金会的支持下。Jelmer Eerkens和Howard Spero将在之前的研究基础上开发一种可靠的方法来追踪加利福尼亚中部古代贝壳珠的地理起源。这种方法是基于保存在用于制造珠子的贝壳中的稳定同位素特征。在加利福尼亚海岸，季节性水温、盐度以及冷海水和富营养盐海水的上涌都有显著的变化。总之，这些影响赋予生长在海岸不同区域的贝壳独特的同位素特征。当一个贝壳在海岸上被收集起来，变成一个贝壳，并在内陆交易，它保留了它最初生长的地方的特征，在它的贝壳的碳酸钙结构中。当考古学家在远离海岸的地方找到贝壳文物时，他们可以从文物和同位素特征中回溯，确定贝壳最初生长的地方。考古学家使用这些类型的技术来追踪原材料在景观中的移动，这使他们能够重建古代的贸易和互动网络。这些贸易网络可以进一步评估人们如何适应不断变化的社会和自然环境。随着新技术的创新和推广，对支持这些技术的原材料的需求也在增加，而可靠地获得当地无法获得的原材料将是很重要的。考古学家可以追溯不同技术的历史和发展，通过考察原材料的来源、人工制品的制作风格，以及这两者是如何随着时间的推移共同进化的。虽然这里要研究的具体案例研究涉及加利福尼亚中部古代海洋贝壳文物的贸易和交换，但这种方法几乎可以应用于世界上任何地方的贝壳文物。在加利福尼亚，土著居民通常用紫色橄榄壳（Olivella biplicata）制作珠子。在18世纪晚期，这些贝壳珠被用作类似货币的用途，在考古遗址中随处可见。确切的数字无法获得，但在过去的100年里，考古学家从加利福尼亚中部的遗址中发现了超过100万颗奥利维拉珠子。即使是在加利福尼亚最早的遗址，可以追溯到一万多年前，也有由橄榄制成的珠子。为什么加州土著选择了这种特殊的物种尚不清楚，但提议的研究可能能够解决这个问题。本项目将资助一名兼职博士后研究员和一至两名加州大学戴维斯分校本科生，对他们进行地球化学和考古分析方面的培训。这些数据和分析结果将通过加州大学戴维斯分校的外展工作与加州中部社区分享，包括在加州大学戴维斯分校人类学博物馆的公开展示，在博德加湾海洋实验室与在校儿童的项目，以及在专业会议上的演讲。