#RMS_026

For centuries, archaeologists operated under the assumption that the Amazon basin was an inhospitable environment for large-scale civilization. The prevailing theory suggested that the region's acidic, nutrient-poor soils were incapable of supporting the intensive agriculture required to feed populous settlements. Consequently, the rainforest was viewed as a pristine, sparsely inhabited wilderness where only small, nomadic tribes could survive. However, recent findings have fundamentally challenged this perspective. Researchers have identified vast expanses of terra preta, or 'dark earth'—a highly fertile, anthropogenic soil found throughout the basin. Unlike the surrounding natural soils, terra preta is rich in charcoal, pottery shards, and organic matter, indicating deliberate engineering by indigenous populations over thousands of years. The existence of these modified soil tracts suggests that pre-Columbian Amazonia was not a virgin wilderness, but a managed landscape capable of sustaining millions of people in complex, sedentary societies. This revelation forces a reconsideration of the historical demography of South America and the sophistication of its early inhabitants' environmental stewardship. What is the main significance of the discovery of terra preta described in the passage?