Doctoral Dissertation Improvement Award: Response to Environmental Alteration on the US Great Plains

极端干旱和干旱时期对人类及其所依赖的资源构成重大挑战。在大卫·梅尔策博士的指导下，瑞安·布雷斯拉夫斯基将进行研究，以了解过去的人们对北美大平原上一场特别严重和持续时间长的干旱事件的反应：大约发生在8000到5000年前的高热气候。重要的是，虽然干旱和干旱是人类社会面临的挑战，但它们的影响在大片地理区域很少是一致的，因此人类可能会产生各种适应性反应，特别是在缺乏驯养食物的觅食社会。在过去的觅食社会中，高热干旱和干旱的地理变异性是否推动了整个空间的生存变异性？这种可变性是否与猎物动物可获得性的下降有关？考古学是解决这些问题和澄清人类社会几千年来适应过程的重要工具。调查人员将通过与大平原上过去的野牛狩猎民族合作来探索这些问题。该项目的结果不仅将揭示大平原的史前，还将揭示气候变化对北美草原的影响。今天，数百万人依赖于Greats Plains生态系统，标志性的美国野牛正在恢复中。随着气候变化的继续，其过去对大平原影响的全貌只会变得更加相关。以前的研究表明，8000-5000年前，北美西部的大部分地区经历了过度干旱和干旱。总体而言，地表水变得稀缺，植被覆盖率下降，动物数量下降。然而，并非所有地区都受到了类似或相同程度的影响，人类对这些影响的反应在整个区域也不会是一致的。这些影响的区域差异以及人类对这些影响的反应仍然没有得到很好的记录。此外，大平原人民的重要资源野牛如何受到高热干旱和干旱的影响，以及这些影响在多大程度上受到地理因素的影响，仍有许多有待了解。为了解决这些问题，该项目将分析位于大平原各地的20多个先前出土的考古遗址中的野牛遗骸。该项目将收集每具野牛遗骸所代表的过去人类猎人的屠宰活动的数据，以及这些被捕食动物经历的环境压力的数据。环境压力将通过营养不良造成的牙齿缺陷和牙齿的稳定同位素化学来检查，稳定的同位素化学反映了过去野牛消耗的食物和水。这些结果将被用来确定气候变化的地理变异性、野牛数量下降以及人类对极端干旱和干旱时期这些下降的反应之间的潜在联系。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Periods of extreme aridity and drought pose significant challenges to humans and the resources on which they depend. Under the direction of Dr. David Meltzer, Ryan Breslawski will undertake research to understand how past peoples responded to one especially severe and long-lasting episode of aridity and drought on the North American Great Plains: the Altithermal, which took place ca. 8,000 to 5,000 years ago. Importantly, while aridity and drought are challenges to human societies, their effects are rarely uniform over large geographic areas, and thus a diversity of human adaptive responses may develop, especially in foraging societies lacking domesticated foods. Did geographic variability in Altithermal aridity and drought drive subsistence variability across space in past foraging societies? Can this variability be linked to declines in the availability of prey animals? Archaeology is an essential tool for resolving these questions and clarifying the processes through which human societies have adapted over millennia. The investigators will explore these questions through work with past bison hunting peoples on the Great Plains. Results from the project will shed light not only on Great Plains prehistory, but also on the effects of climate change on North America’s grasslands. Millions of people depend on the Greats Plains ecosystem today, as does the ongoing recovery of the iconic American bison. As climate change continues, the full picture of its past impacts on the Great Plains will only become more relevant.Previous research suggests that 8000–5000 years ago much of western North America experienced hyperaridity and drought. Overall, surface water became scarce, vegetation cover decreased, and animal populations declined. However, not all areas were impacted in similar ways or to the same degree, and human responses to these impacts would not have been uniform throughout the region. Regional variation in these impacts and the human responses to them remain poorly documented. Further, much remains to be learned about how bison, a vital resource for Great Plains peoples, were impacted by Altithermal drought and aridity, and the degree to which these impacts were mediated by geography. To resolve these issues, the project will analyze bison remains from over two dozen previously excavated archaeological sites dating to this period and located throughout the Great Plains.The project will collect data on the butchery activities of past human hunters represented by each set of bison remains, as well as data on the environmental stresses experienced by these prey animals. Environmental stresses will be examined through dental defects that result from malnutrition, and through the stable isotope chemistry of teeth, which reflects the food and water that past bison consumed. The results will be used to identify potential links between geographic variability in climate change, bison population declines, and human responses to those declines during this period of extreme aridity and drought.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.