托福综合写作

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The extinction of the megafauna—large animals such as woolly mammoths, giant ground sloths, and saber-toothed cats—at the end of the Pleistocene epoch has long puzzled scientists. While multiple hypotheses exist, the most compelling explanation is overhunting by early humans. First, the timing of extinctions closely correlates with human migration. In North America, megafauna disappeared roughly 13,000 years ago, just as Clovis hunters arrived, and similar patterns are seen in Australia and Madagascar. Second, archaeological evidence supports human predation: kill sites with butchered remains, such as the Lehner site in Arizona, show that humans actively hunted these animals. Finally, climate change alone cannot explain the extinctions, because megafauna had survived previous glacial-interglacial cycles without such catastrophic losses. Therefore, human hunting, not climate, was the primary driver of these extinctions.

🎧 听力讲座

The reading’s argument that human overhunting caused megafaunal extinctions is flawed. While timing correlations exist, they are not proof. In many regions, like Europe and Asia, megafauna coexisted with humans for tens of thousands of years before disappearing, and in Siberia, some species vanished before humans arrived. Second, the archaeological record is sparse: only a handful of kill sites exist, and many are contested—some bones show no cut marks, and tools found may not have caused death. Finally, climate change cannot be dismissed so easily. The late Pleistocene saw rapid, extreme temperature swings and shifts in vegetation, which would have stressed large animals with specific dietary needs. For instance, the woolly mammoth’s habitat contracted dramatically as forests replaced grasslands. These climate-driven habitat changes likely reduced populations to critical levels, making them vulnerable to any additional pressure, even modest hunting.