托福综合写作

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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, the timing of mammoth decline coincides with the rapid warming at the end of the last Ice Age (approximately 10,000 years ago), which drastically reduced the open grassland habitats (steppe) that mammoths depended on. As forests and wetlands expanded, mammoth populations became fragmented and isolated, leading to reduced genetic diversity and lower reproductive success. Second, carbon dating of mammoth remains shows that many populations survived well after humans arrived in their regions, and some even thrived on isolated islands like Wrangel Island until about 4,000 years ago, when sea levels rose and freshwater sources disappeared. This suggests that human hunting pressure was not sufficient to cause extinction. Third, the extinction of other large Ice Age mammals, such as the giant beaver and the shrub ox, also occurred during periods of rapid climate change, even though they were not primary targets of human hunters. Thus, the pattern of extinction aligns more strongly with climate-induced habitat loss than with human predation.

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The reading's argument that climate change alone caused the woolly mammoth's extinction is not convincing. While climate change did alter habitats, human hunting was the decisive factor. First, the claim that mammoths survived long after humans arrived ignores the fact that human populations were small and dispersed at first, but as human technology improved—such as the development of spears and coordinated hunting strategies—they became far more effective predators. The final extinction on Wrangel Island around 4,000 years ago actually corresponds to the arrival of seafaring humans, not just rising sea levels. Second, the reading overlooks that mammoth populations on mainland Eurasia and North America disappeared within a few hundred years of human arrival, even in areas where climate remained relatively stable. For example, mammoths persisted in parts of Siberia until humans with advanced hunting tools appeared, and their disappearance there was abrupt. Third, the example of other large mammals is misleading: species like the giant beaver may have been more sensitive to climate, but mammoths were uniquely targeted by humans for their meat, bones, and tusks, which were used for tools and shelter. The archaeological record shows kill sites with mammoth remains and human-made weapons, a pattern not seen for other climate-sensitive species. Therefore, human overhunting, not climate, was the primary cause.