托福综合写作

📖 阅读文章

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 correlates with the end of the last Ice Age, when global temperatures rose rapidly. As glaciers retreated, mammoth habitats—cold steppe grasslands—shrank dramatically, reducing their food supply. Second, genetic studies indicate that mammoth populations experienced severe bottlenecks long before humans arrived in their final refuges, such as Wrangel Island. These bottlenecks imply that climate-driven habitat fragmentation weakened the species, making them vulnerable to extinction even without hunting. Third, archaeological evidence shows that human hunting of mammoths was sporadic and localized, not widespread enough to cause extinction. In contrast, the warming trend at the end of the Pleistocene was a global event that affected all mammoth populations simultaneously, providing a more parsimonious explanation for their demise.

🎧 听力讲座

The reading’s argument that climate change alone drove mammoth extinction is flawed. First, while climate did warm, mammoths had survived previous interglacial periods with similar temperature increases, such as the Eemian, which occurred 120,000 years ago. Thus, climate change alone cannot explain why they perished only in the late Pleistocene. Second, the genetic bottlenecks cited in the reading actually support human impact, not refute it. The severe reduction in population size on Wrangel Island happened after humans arrived there, and the timing matches the appearance of human artifacts. This suggests that hunting, not climate, caused the bottleneck. Third, the archaeological record is more extensive than the reading admits. Recent excavations in North America and Siberia have revealed mass kill sites with mammoth bones, indicating that humans hunted them systematically, not sporadically. Moreover, human populations were expanding exactly when mammoths disappeared, and the introduction of advanced projectile weapons made hunting more efficient. Therefore, human overhunting, perhaps combined with climate stress, is the more likely cause.