Paleoecologists analyzing sediment cores from Lake Kerinci observed an abrupt collapse in endemic broadleaf canopy pollen approximately 4,200 years ago, coinciding precisely with a massive spike in micro-charcoal deposits. Because micro-charcoal is a definitive indicator of intense forest fires, the researchers concluded that widespread wildfires triggered by regional drought were the direct cause of the broadleaf canopy collapse.
Statement: Fossilized pollen records from nearby, hydrologically isolated basins that experienced the same regional drought but lacked charcoal deposits show that broadleaf canopy tree populations remained stable during that period; this finding strengthens the researchers' conclusion.
Answer: Answer
Answer
True. The supplementary finding strengthens the argument by establishing a control condition that isolates wildfire as the necessary causal agent of the tree population collapse.
The conclusion asserts a specific causal attribution: wildfires caused the collapse of broadleaf trees. A central weakness in such arguments is the presence of confounding variables (e.g., the drought itself could have dehydrated and killed the trees directly, with fires acting merely as an incidental byproduct). The supplementary finding introduces a classic negative control: where the drought was present but fire was absent, the trees survived. Demonstrating that the effect disappears when the proposed cause is removed strongly substantiates the causal link.
Step-by-Step Solution
Key Concept
Strengthening Causal Claims through Control Comparison and Ruling Out Alternative Causes
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