Collaborative Research: Dating of Hominid Sites by the Racemization and Accelerator Mass Spectrometry of Protein Amino Acids in Ostrich Eggshells

合作研究：通过鸵鸟蛋壳中蛋白质氨基酸的外消旋和加速器质谱法测定原始人类位点

• 批准号: 9011657
• 负责人: P. Edgar Hare
• 金额: $ 7.12万
• 依托单位: Carnegie Institution of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-06-01 至 1992-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9011657&HistoricalAwards=false
• 关键词: Collaborative; Research; Dating; Hominid; Sites

The preservation of amino acids within the calcite matrix of eggshells of the African Ostrich (Struthio camelus), has been shown to approximate a closed system. Indigenous proteinaceous materials are bound within the calcite crystals and there is essentially no loss of amino acids due to leaching or diffusion despite a steady degradation of high molecular weight polypeptide material to low molecular weight peptides and free amino acids. Because of this closed system behavior, the natural variability of specific degradation reactions in samples of known age is far less that in other carbonate systems; additionally, the kinetics of amino acid racemization are much simpler to model than in more open systems such as molluscan and foraminiferal fossils. Consequently, the potential for precise age, and/or paleotemperature calculations from the extent of these reactions is superior for the eggshell compared to all other media studies to date. Hominid lineages have a long history of interaction with ostriches. The ostrich egg, weighing between one and two kilograms, has been utilized as a food source by hominids for more that two million years. It is found commonly in association with hominid artifacts in the lowest strata at Olduvai Gorge, and in older beds elsewhere in Tanzania. By the end of the Middle Stone Age humans were also using the eggshell as a source material for decorative items such as beads, and ostrich eggshell fragments are commonly found in association with occupation levels at sites across Africa, the Near East, and Asia, where the ostrich has only recently become extinct. The ubiquitous occurrence of ostrich eggshell in hominid sites, especially in stratified sites, offers the potential of utilizing the remarkably straight forward time-dependent characteristics of amino acid racemization in the eggshell as a means of dating occupation levels beyond the range of radiocarbon. The principal investigators will conduct an analytical program that will focus on developing a more precise model of racemization kinetics in the eggshells of ostrich and other avian genera, including the modeling of decomposition reactions that hold the promise of extending the dating potential back into the Pliocene. They will apply the racemization reaction in ostrich eggshell to address questions related to the earliest appearance of anatomically modern humans in Africa, the emergence of specialized human cultures, and the migration of Homo sapiens sapiens across the Near East and Asia. They will also extend the eggshell research into Europe and Australia by utilizing the common occurrence of owl eggshell in the former, and emu eggshell in the latter area. Improved chronologies in these areas are relevant to questions related to persistence of isolated populations of Homo erectus and the colonization of Australia and Europe, including the possible interactions between different species, or subspecies, of the genus Homo.

非洲鸵鸟(骆驼)蛋壳方解石基质中氨基酸的保存已被证明接近于一个封闭的系统。本地蛋白质类物质结合在方解石晶体中，尽管高相对分子质量的多肽物质稳定地降解为低相对分子质量的多肽和游离氨基酸，但基本不会因淋溶或扩散而损失氨基酸。由于这种封闭的系统行为，特定降解反应的自然变异性在已知年龄的样品中远远低于其他碳酸盐系统；此外，氨基酸外消旋动力学比更开放的系统，如软体动物和有孔虫化石，建模要简单得多。因此，与迄今为止所有其他媒体研究相比，根据这些反应的程度来计算准确的年龄和/或古温度的可能性对蛋壳来说是更好的。原始人的血统与鸵鸟有很长的互动历史。鸵鸟蛋重1至2公斤，200多万年来一直被原始人用作食物来源。它通常与奥杜瓦伊峡谷最低层的原始人人工制品有关，也与坦桑尼亚其他地方的老床有关。到中世纪石器时代结束时，人类也开始使用蛋壳作为珠子等装饰物品的原料，在非洲、近东和亚洲的一些地点，鸵鸟蛋壳碎片经常被发现与占领水平有关，这些地方的鸵鸟最近才灭绝。鸵鸟蛋壳在人类遗址中的普遍存在，特别是在层状遗址中，提供了利用蛋壳中氨基酸消旋的非常直接的时间相关特性作为一种方法来测定放射性碳范围以外的职业水平的可能性。主要研究人员将进行一项分析计划，重点是开发鸵鸟和其他鸟类蛋壳中外消旋动力学的更精确模型，包括对分解反应的建模，这些反应有望将测年潜力延长到上新世。他们将应用鸵鸟蛋壳中的消旋反应来解决与非洲解剖学上的现代人最早出现、专门的人类文化的出现以及智人在近东和亚洲的迁徙有关的问题。他们还将把蛋壳研究扩展到欧洲和澳大利亚，利用前者常见的猫头鹰蛋壳和后者地区常见的鸵鸟蛋壳。这些地区改进的年表与与直立人孤立种群的持续存在以及澳大利亚和欧洲的殖民有关的问题有关，包括人属不同物种或亚种之间可能的相互作用。