The extinction of the woolly mammoth has long been attributed to human overhunting, but recent evidence suggests that climate change was the primary driver. First, human populations in Siberia and North America were sparse during the late Pleistocene, with estimates of only a few thousand individuals across vast territories. Such low densities would have made it difficult to hunt mammoths to extinction, especially given the mammoth's large size and mobility. Second, the woolly mammoth's range contracted dramatically around 10,000 years ago, coinciding with a period of rapid warming known as the Bølling-Allerød interstadial. This warming caused the replacement of open steppe grasslands with dense forests and wetlands, reducing the mammoth's preferred habitat. Third, genetic studies of fossil mammoth remains show a decline in genetic diversity before the final extinction, indicating population stress due to habitat fragmentation rather than sudden hunting pressure. Therefore, while humans may have contributed locally, climate-driven habitat loss was the decisive factor.
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The reading claims that climate change, not human hunting, drove the woolly mammoth to extinction. However, this argument is flawed. First, while human populations were small, they were highly effective hunters, using sophisticated tools and coordinated drives. Archaeological sites in Siberia contain mammoth bone piles with butchering marks, suggesting that humans could kill multiple mammoths at once. Even low-density human groups could exert intense pressure on slow-reproducing megafauna. Second, the timing of habitat change does not match the extinction pattern. Mammoths survived in refugia like Wrangel Island for thousands of years after the warming, despite similar vegetation shifts. This shows that habitat loss alone was not fatal. Third, the decline in genetic diversity cited by the reading may be a result of small population sizes long before humans arrived, and it does not prove a gradual decline from climate stress. In fact, the final extinction on Wrangel Island occurred around 2000 BCE, when humans first reached the island, strongly implicating hunting as the final blow. Thus, the evidence points to humans as the primary cause.
📝 写作提示 Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
