Historically, historians attributed the rapid decline of the classic Maya civilization in the ninth century CE primarily to catastrophic megadroughts. Recently, however, archaeologist Dr. Marcus Thorne has proposed that systemic agricultural degradation, rather than climate shift alone, was the decisive driver. Thorne argues that the Maya’s intensive terracing and slash-and-burn farming depleted topsoil nutrients, initiating a feedback loop of falling yields and social unrest. To support this claim, Thorne points to soil core samples from the Copán Valley showing a dramatic decrease in maize pollen and a concurrent rise in bracken fern spores—a weed that thrives in depleted, acidic soils—dating to approximately 820 CE. Critics of Thorne’s thesis argue that the Copán Valley was an outlier with unusually fragile soil, and that regional climate models still show that a multi-decade drought occurred during the same period, which would have suppressed crop yields regardless of soil health.
Based on the passage, which of the following discoveries would most directly undermine Dr. Thorne's argument regarding the primary cause of the agricultural decline in the Copán Valley?
- AEvidence that neighboring Maya cities in regions with resilient volcanic soils did not experience a decline in maize yields during the ninth century.
- BHistorical records showing that Maya farmers in the Copán Valley abandoned maize cultivation and transitioned to cultivating drought-resistant tubers by 850 CE.
- Soil core samples indicating that the rise of bracken fern spores in the Copán Valley occurred decades prior to the implementation of intensive terracing and farming.Answer
- DA revised climate model indicating that the ninth-century megadrought was slightly less severe in the Copán Valley than in the northern Maya lowlands.