The Effects of Climate and Population Density on Agricultural Production

向粮食生产的过渡是人类历史上最重要的事件之一。越来越多的证据表明，在人口崩溃和环境变化的时期，农业的持续存在表明，向粮食生产的过渡是人类无法恢复的临界点，但至少有一个案例研究提供了相反的证据。北美西部盆地高原地区的弗里蒙特人在大约1550-650年前（公元450-1350年）种植玉米近一千年，然后在欧洲人接触之前的几个世纪放弃了农业和他们的农业村庄。在弗里蒙特的一些地区，农业比其他地区停止得更早，但到公元1350年，弗里蒙特作为考古建筑群的大部分定居模式特征已不复存在。在与欧洲人的接触中，生活在大盆地东部和科罗拉多高原北部的群体已经恢复了移动狩猎和采集。弗里蒙特农业的起源和消亡的原因一直备受争议，但缺乏共识。该项目将产生大量关于饮食、气候和人口统计的数据，以解决对玉米依赖的上升、时空变化和弗里蒙特综合体的衰落问题，这将作为一个模型系统，探索导致农业崩溃的动态。几种方法将被用来重建可能决定弗里蒙特人口在玉米农业上的投资和他们决定返回觅食的变量。人口统计——人口的规模和分布——是一个关键因素。弗里蒙特地区放射性碳的总年代将被用作史前人口密度的代用物。研究表明，人口增长给野生资源带来了压力，并可能成为对驯养动物依赖的驱动力。因此，弗里蒙特当地种群的大小和结构的变化可以解决对玉米依赖的变化。农业适宜性建模将进一步为这项工作提供信息。影响玉米产量的关键气候变量，如降水、生长日数、土壤水分和土壤化学对玉米种植的成功至关重要。现代数据将与树木年轮年表进行临时调整，以重建整个弗里蒙特地区的古气候。最后，将分析大量弗里蒙特个体的骨骼化学，以确定玉米饮食重要性的时空变化。一旦收集了所有数据，将评估每个因素的相对影响。结果分析将检验在保持时间、空间和其他混淆因素不变的情况下，个体对玉米农业的依赖如何作为每个解释变量的函数而变化。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。

The transition to food production represents one of the most significant events in human history. Growing evidence for the persistence of agriculture through periods of population collapse and environmental change suggests that the transition to food production is a tipping point from which human populations cannot return, but at least one case study provides evidence to the contrary. The Fremont in the Basin-Plateau region of Western North America farmed maize for nearly a millennium, from about 1550-650 years ago (AD 450-1350), then abandoned agriculture and their farming villages a few centuries prior to European contact. Farming ceased earlier in some regions of the Fremont landscape than in others but by AD 1350 most of the characteristics of settlement pattern that identified the Fremont as an archaeological complex were no longer present. At European contact groups living in the eastern Great Basin and on the northern Colorado Plateau had returned to mobile hunting and gathering. Reasons for both the origin and demise of Fremont farming have been hotly debated, but a consensus is lacking. This project will generate extensive data on diet, climate and demography in order to address the rise, spatiotemporal variation in reliance on maize and fall of the Fremont complex, which will serve as a model system to explore the dynamics that lead to agricultural collapse. Several approaches will be used to reconstruct the variables that likely determined the investment of Fremont populations in maize agriculture and their decision to return to foraging. Demography - the size and distribution of human populations - is one critical factor. Summed radiocarbon dates from Fremont contexts will be used as a proxy for prehistoric population densities. Research has shown population growth puts pressure on wild resources and can be a driver of reliance on domesticates. Thus, variation in the size and structure of local Fremont populations may address variation in reliance on maize. Modeling agricultural suitability will further inform this work. Key climatic variables that affect maize productivity such as precipitation, growing degree days, soil moisture and soil chemistry are critical to the success of maize farming. Modern data will be temporally adjusted with tree-ring chronologies to reconstruct paleo-climate across the Fremont region. Finally the bone chemistry of a large collection of Fremont individuals will be analyzed to determine spatiotemporal variation in the dietary importance of maize. Once all the data are assembled the relative influence of each factor will be evaluated. The resulting analyses will examine how an individual's reliance on maize agriculture varied as a function of each explanatory variable while holding time, space and other confounds constant.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.