This chapter explores evidence of a dramatic rise in sea levels post-Last Glacial Maximum and a transition from slightly cooler, drier conditions to more humid rainforest environments around 16,000 years ago, with fluctuations during the Younger Dryas period in consideration of how these changes influenced human habitation and ecological diversity. The material culture that merits such considerations stems from potentially rare astronomical and ecological narratives recorded in ancient paintings and excavated stone tools, lithic debris, and possibly landscape modifications from Monte Alegre, Brazil. Despite these changes, the Amazon rainforest has maintained its biome stability, while undergoing identifiable shifts in species prevalence and environmental resources, suggesting a resilient ecological framework in response to climatic variations. However, at the beginning of the Younger Dryas, Paleoindian occupation was abandoned, suggesting some correlations may have driven humans away for several thousand years.