TOEFL統合ライティング

📖 読解文章

The extinction of the woolly mammoth has long been attributed to human hunting, but recent evidence suggests that climate change was the primary driver. First, the timing of mammoth decline coincides with the end of the last Ice Age, when temperatures rose dramatically. As forests replaced grasslands, mammoths lost their preferred habitat. Second, genetic studies show that mammoth populations were already small and genetically isolated long before humans arrived in their final refuges, indicating that they were vulnerable due to environmental stress. Third, archaeological evidence indicates that human hunting pressure was minimal: only a few mammoth kill sites have been found, and these are concentrated in specific regions, not widespread enough to cause extinction.

🎧 リスニング講義

The lecture challenges the reading's claim that climate change alone drove mammoths to extinction. While it is true that warming altered habitats, the reading overlooks the fact that mammoths had survived previous interglacial periods with similar warming. Thus, climate change alone cannot explain their final disappearance. Furthermore, the genetic evidence mentioned in the reading is misleading: small populations can be a result of hunting, not just environmental stress. Recent DNA analysis shows a sudden drop in genetic diversity around the time humans arrived, which points to overhunting. Finally, the scarcity of kill sites is not surprising because mammoth bones preserve poorly in many environments, and hunters may have used traps or scavenged carcasses. In fact, new discoveries in Siberia reveal mammoth bone piles with cut marks, suggesting that hunting was far more common than the reading suggests.