Read the following passage regarding Amazonian pedology and pre-Columbian agriculture:
For much of the twentieth century, soil scientists examining the nutrient-poor oxisols of the central Amazon Basin operated under the assumption that pre-Columbian indigenous populations were strictly constrained by ecological limits, incapable of sustaining dense, sedentary societies. According to this traditional view, the infertile, highly leached soils could support only transient, slash-and-burn horticulture. However, the identification of extensive patches of 'terra preta'—dark, nutrient-rich soils containing high concentrations of charcoal, pottery fragments, and organic waste—forced a fundamental reassessment of Amazonian historical demography. Initial accounts posited that terra preta formed inadvertently through centuries of kitchen-refuse accumulation around small settlement sites. Nonetheless, recent micro-botanical and elemental analyses reveal a deliberate, highly sophisticated soil-management strategy: biochar was intentionally integrated into soil matrices alongside bone meal and organic compost to fix nitrogen and prevent nutrient leaching. Far from being passive victims of tropical soil limitations, pre-Columbian societies actively engineered resilient agricultural landscapes. Granted, some modern agronomists caution that attempting to replicate ancient terra preta practices under contemporary industrial farming regimes may face scalability bottlenecks due to biomass requirements. Nevertheless, tracking the structural evidence of these anthropogenic soils demonstrates that ancient Amazonian land-use strategies fundamentally undermine long-held assumptions regarding environmental carrying capacity.
Match each structural pivot or transition phrase from the passage to its precise rhetorical function within the author's overall argument trajectory.
- However (following the description of the traditional view)Signals a major empirical counter-observation that overturns the long-standing consensus regarding environmental constraints on population density.
- Nonetheless (following the initial inadvertent-accumulation hypothesis)Rebuts a secondary alternative hypothesis of accidental soil modification by introducing scientific evidence of deliberate, systematic engineering.
- Granted (preceding modern agronomists' reservations)Concedes a potential practical limitation regarding modern application while maintaining the core claim of ancient agricultural sophistication.
- Nevertheless (preceding the final concluding claim)Reasserts the primary theoretical significance of the findings after acknowledging a contemporary operational caveat.