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赖以生存的资源构成重大挑战。在David Meltzer博士的指导下，Ryan Breslawski将进行一项研究，以了解过去的人们是如何应对北美大平原上一次特别严重和持久的干旱事件的：发生在大约8000到5000年前的高热期。重要的是，尽管干旱和干旱是人类社会面临的挑战，但它们对大地理区域的影响很少是一致的，因此人类适应反应可能会出现多样性，特别是在缺乏驯化食物的觅食社会。在过去的觅食社会中，高热干旱和干旱的地理变异是否驱动了空间上的生存变异？这种可变性是否与猎物数量的减少有关？考古学是解决这些问题和阐明人类社会几千年来的适应过程的重要工具。调查人员将通过与过去在大平原上狩猎野牛的人们的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历史，而且还将揭示气候变化对北美草原的影响。如今，数以百万计的人依靠大平原的生态系统生存，标志性的美洲野牛也在不断恢复。随着气候变化的持续，它过去对大平原的影响的全貌只会变得更加重要。先前的研究表明，8000-5000年前，北美西部的大部分地区经历了极度干旱和干旱。总的来说，地表水变得稀缺，植被覆盖减少，动物数量下降。然而，并非所有地区都受到了类似方式或相同程度的影响，人类对这些影响的反应在整个地区也不可能是一致的。这些影响的区域差异以及人类对这些影响的反应仍然缺乏文献记录。此外，关于作为大平原人民的重要资源的野牛是如何受到高温带干旱和干旱的影响，以及这些影响在多大程度上受到地理因素的调节，还有很多有待了解的地方。为了解决这些问题，该项目将分析20多个先前挖掘的考古遗址中的野牛遗骸，这些遗址可追溯到这一时期，遍布大平原。该项目将收集每组野牛遗骸所代表的过去人类猎人屠杀活动的数据，以及这些猎物所经历的环境压力的数据。环境压力将通过营养不良导致的牙齿缺陷和牙齿的稳定同位素化学来检查，这反映了过去的野牛消耗的食物和水。研究结果将用于确定气候变化的地理变异、野牛数量下降以及人类对这一极端干旱时期野牛数量下降的反应之间的潜在联系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.