Paleoclimate Reconstruction Based on the Stable Carbon Isotopic Composition of Bone Collagen from Small Herbivores Recovered in Archaeological Assemblages

基于考古组合中发现的小型食草动物骨胶原稳定碳同位素组成的古气候重建

• 批准号: 0804169
• 负责人: Raymond Mauldin
• 金额: $ 15.14万
• 依托单位: University of Texas at San Antonio
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0804169&HistoricalAwards=false
• 关键词: Paleoclimate; Reconstruction; Based; Stable; Carbon

With National Science Foundation support, Drs. Raymond Mauldin, Debajyoti Paul, and Robert Hard will conduct collaborative research focused on developing short-term, local measures of past ecological conditions using patterns of stable carbon isotopes in collagen extracted from small herbivores from archaeological sites. The two year project brings together staff from the Laboratory for Stable Isotope Geochemistry (LSG), graduate and undergraduate students from the Department of Geology at the University of Texas at San Antonio (UTSA), researchers from the Center for Archaeological Research (CAR), and graduate and undergraduate students from the Department of Anthropology at UTSA. Most paleoclimate reconstructions in archaeology operate at large temporal scales (hundreds of years) and unknown, poorly defined, or extremely large spatial scales. Human foragers, however, do not initiate adaptive shifts in response to changes that occur over centuries, but in response to short term events that commonly operate at a seasonal or yearly timeframes, and that cover kilometers rather than continents. While long-term, large scale climate changes will certainly influence which adaptive strategies are ultimately successful, it is at these smaller temporal and spatial scales that adaptive decisions are initiated. This research differs from most other archaeological paleoclimate investigations in that it targets small herbivores, such as jack rabbits and cottontails, which can provide data on climate at scales appropriate for exploring human adaptations. These herbivores consume a variety of plants that use one of two different photosynthetic pathways, termed C4 or C3, to extract carbon dioxide from their environment. Measurements of carbon isotope ratios in collagen extracted from herbivore bones can provide an estimate of the relative contribution of C4 or C3 plants in herbivore diet. As these two different plant pathways are favored by different environmental conditions, with C4 plants more common in warm, arid settings, and C3 plants more common in cooler, moister settings, the relative contribution of C4 or C3 plants in jack rabbit and cottontail bone collagen can provide data to reconstruct aspects of past vegetation and climate. Jack rabbits and cottontails have a number of distinct advantages in the development of appropriate spatial and temporal measures of past climates. They have short life spans, seldom exceeding 3 years in length. Lifetime range sizes are commonly less than 1 square kilometer. As such, the diets of these small herbivores reflect local, short-term patterns of vegetation. Collagen extracted from jack rabbit and cottontail bones, collected from well-dated archaeological contexts, can provide a record of vegetation, and shifts in vegetation, at short temporal and small spatial scales directly relevant to understanding human adaptations. While using archaeological samples obtained from three ecologically distinct areas of Texas, and focused on hunter-gather adaptations that span the last 4,000 years, this research has broad implications for investigations of human adaptation. Small herbivores are present in archaeological and paleontological sites throughout much of the world, and from a variety of temporal contexts. Therefore, the findings of this collaborative research between the LSG (Geology), Anthropology, and CAR at UTSA will be of interest to the broader scientific community, both nationally and globally.

在美国国家科学基金会的支持下，雷蒙德·莫尔丁、德巴约蒂·保罗和罗伯特·哈德将进行合作研究，重点是利用从考古遗址中提取的小型食草动物胶原蛋白中的稳定碳同位素模式，开发短期的、局部的过去生态条件测量方法。这个为期两年的项目汇集了来自稳定同位素地球化学实验室（LSG）的工作人员，来自德克萨斯大学圣安东尼奥分校地质系（UTSA）的研究生和本科生，考古研究中心（CAR）的研究人员，以及来自UTSA人类学系的研究生和本科生。考古学中的大多数古气候重建都是在大的时间尺度（数百年）和未知的、不明确的或极大的空间尺度上进行的。然而，人类觅食者并不是为了应对几个世纪以来发生的变化而发起适应性转变，而是为了应对短期事件，这些事件通常以季节或年为时间框架，覆盖公里而不是大陆。虽然长期、大规模的气候变化肯定会影响哪些适应战略最终取得成功，但正是在这些较小的时间和空间尺度上，才启动了适应性决策。这项研究与大多数其他考古古气候调查的不同之处在于，它的目标是小型食草动物，如野兔和棉尾兔，它们可以提供适合探索人类适应的尺度的气候数据。这些食草动物食用各种植物，这些植物使用两种不同的光合作用途径之一，称为C4或C3，从它们的环境中提取二氧化碳。测定草食动物骨骼中胶原蛋白的碳同位素比值可以估计C4或C3植物在草食动物饮食中的相对贡献。由于这两种不同的植物途径受不同的环境条件的影响，C4植物在温暖干旱的环境中更常见，C3植物在凉爽潮湿的环境中更常见，C4或C3植物在兔和棉尾骨胶原中的相对贡献可以为重建过去植被和气候的各个方面提供数据。在对过去气候进行适当的时空测量方面，杰克兔和棉尾兔具有许多明显的优势。它们的寿命很短，很少超过3年。寿命范围通常小于1平方公里。因此，这些小型食草动物的饮食反映了当地短期的植被模式。从历史悠久的考古背景中提取的杰克兔和棉尾骨胶原蛋白可以在短时间和小空间尺度上提供植被和植被变化的记录，这与理解人类的适应性直接相关。虽然使用了从德克萨斯州三个生态截然不同的地区获得的考古样本，并专注于过去4000年的狩猎-采集适应，但这项研究对人类适应的调查具有广泛的意义。小型食草动物在世界各地的考古和古生物遗址中都存在，并且来自各种各样的时间背景。因此，这项LSG（地质学），人类学和UTSA CAR之间的合作研究的结果将引起更广泛的科学界的兴趣，无论是在国内还是在全球。