Dissertation: An Investigation of Prehistoric Population Relationships Using Ancient DNA: The Test Case of Azapa Valley, Northern Chile

在Andrew Merriwether博士的指导下，MS Graciela Cabana将为她的博士论文收集数据。她的研究目标是利用从骨骼材料中提取的DNA数据来了解位于智利北部沿海的阿扎帕山谷的早期史前。考古证据表明，在智利的这个地区，以及南美洲太平洋沿岸的许多其他地区，最早的人类以狩猎和采集为生，主要依靠鱼类、贝类和可食用的野生植物。最终，这种饮食被驯化的食物所取代，并在此基础上出现了复杂的社会。然而，考古学家和体质人类学家不知道这种从依赖野生资源到种植资源的转变是由于原位变化还是人口更替。在阿扎帕山谷发现的陶器证据表明，高地陶器最早出现的时间恰好是向农业的转变，再加上一些骨骼分析，这些数据支持了人口更替假说。然而，其他研究表明，观察到的变化可能反映了贸易，早期和晚期骨骼样本之间的差异可能是随着时间的推移而发生的变化。为了解决这个问题，卡巴纳将从狩猎、采集和农业时期的骨骼中提取DNA。初步分析表明，可以获得保存完好的DNA。她开发了一个模拟模型，假设一个单一的人口，估计随着时间的推移可能发生的变化量。然后就可以确定实际的DNA差异是否超过预测。这项研究之所以重要，有几个原因。考古学家多年来一直在推测导致南美洲农业发展和传播的过程。由于物品可以远距离交易，出土的陶瓷和其他物质文化物品提供了有用但不是决定性的信息。卡巴纳将为这个问题带来一个强大的新数据来源。她开发的方法有望对解决世界上许多地方的许多考古问题有用。

Under the direction of Dr. Andrew Merriwether, MS Graciela Cabana will collect data for her doctoral dissertation. The goal of her research is to utilize DNA data extracted from skeletal materials to understand the early prehistory of the Azapa Valley which is located in coastal northern Chile. Archaeological evidence indicates that in this region of Chile, as well as many other areas along South America's Pacific coast, the earliest human populations subsisted as hunters and gatherers relying largely on fish, shellfish and edible wild plants. Eventually this diet was replaced by domesticated cultigens and on this basis complex societies arose. Archaeologists and physical anthropologists however do not know whether this transition from reliance on wild to cultivated resources resulted from in situ change or population replacement. Ceramic evidence in the Azapa Valley demonstrates that highland type pottery first appears coincidentally the switch to agriculture and together with some skeletal analyses these data support a population replacement hypothesis. Other studies however suggest that the changes observed may reflect trade and that the differences between early and late skeletal samples can result from in place change over time. To address this question MS Cabana will extract DNA from skeletons dating from both hunting and gathering and agricultural periods. Preliminary analyses indicate that well preserved DNA can be obtained. She has developed a simulation model which, assuming a single population, estimates the amount of change likely over time. One can then determine whether the actual DNA difference exceeds that predicted.This research is important for several reasons. Archaeologists have speculated for many years on the processes which led to the development and spread of agriculture in South America. Because objects can be traded over long distances excavated ceramics and other items of material culture provide useful but not definitive information. MS Cabana will bring a powerful new source of data to bear on this question. The methods she develops will, hopefully, be useful to address many archaeological questions in many parts of the world.