Agriculture, Paleoenvironment, and Human Occupation in the Pacific Coastal Lowlands of Southern Mesoamerica

在美国国家科学基金会的支持下，Hector Neff博士和他的合作者将完成对危地马拉太平洋沿岸五个沉积物岩心的分析，这些岩心被认为跨越了人们首次开始为农业和其他生计目的改变景观的时间段。一个地点的初步结果表明，人们在公元前5000年之前将玉米或玉米的直系祖先带到该地区，并且在公元前3500年左右开始发生戏剧性的农业集约化。通过植物微体化石的变化频率，可以在沉积物芯中检测到人类改造和其他景观变化的信号（植硅体和花粉）和木炭以及沉积速率的变化。当人们砍伐或烧毁热带森林用于农业时，杂草和木炭在记录中变得更加常见，因为树木和其他森林物种减少了。随着森林覆盖的消失，沉积速率也趋于增加。玉米和其他农作物可以从花粉和植硅体中识别，综合证据提供了最安全的识别（植硅体是积累生长植物的微观二氧化硅体）。这些变化被放置在一个年代背景下的AMS放射性碳测年的有机物从选定的水平在核心。公元前3500年至公元前800年期间，太平洋沿岸的危地马拉特别令人感兴趣，因为正是在这一时期，中美洲复杂社会的许多独特特征融合在一起。到这一时期结束时，大多数地方的人们严重依赖玉米农业，建造了具有纪念性建筑和精心制作的石雕的大型遗址，社会分层出现了。生存方式的根本转变，人们对特定地点的束缚增加，以及对建筑基础设施的重大投资的开始，构成了中美洲文明的出现。不幸的是，这个太平洋地区一直相对研究不足，序列的细节知之甚少，例如，墨西哥湾沿岸的奥尔梅克中心地带。Neff博士和他的同事们的工作将为这种文化进步建立一个环境背景，并提供对这一过程本身的见解。

With National Science Foundation support Dr. Hector Neff and his collaborators will complete the analysis of five sediment cores from Pacific coastal Guatemala that are known to span the time periods when people first began modifying the landscape for agriculture and other subsistence purposes. Preliminary results from one location suggest that people brought maize or a direct ancestor of maize to the region before 5000 B.C. and that dramatic agricultural intensification took place beginning around 3500 B.C. The signal of human modification and other landscape changes can be detected in sediment cores via the changing frequencies of plant microfossils (phytoliths and pollen) and charcoal together with variation in sedimentation rates. When people cut or burn down the tropical forest for agriculture, weeds and charcoal become more common in the record as trees and other forest species decline. Sedimentation rates also tend to increase as forest cover is removed. Maize and other agricultural crops can be identified both from pollen and phytoliths, the combined evidence providing the most secure identification (phytoliths are microscopic silica bodies that accumulate growing plants). These changes are placed in a chronological context by AMS radiocarbon dating of organic matter from selected levels in the cores. The period between 3500 B.C. and 800 B.C. in Pacific coastal Guatemala is of particular interest because it was during this period that many of the distinctive characteristics of Mesoamerican complex societies coalesced. By the end of the period, people in most locations depended heavily on maize agriculture, large sites with monumental architecture and elaborate stone sculpture were being constructed, and social stratification had appeared. The fundamental shifts in subsistence, the increased tethering of people to specific locations, and the beginning of major investment in architectural infrastructure constituted the emergence of Mesoamerican civilization. Unfortunately this Pacific region has been relatively understudied and details of the sequence are poorly known compared, for example, to the Olmec heartland on the Gulf Coast of Mexico. The work of Dr. Neff and his colleagues will both establish an environmental context for this cultural progression and provide insight into the process itself.