TOEFL統合ライティング

📖 読解文章

The extinction of the woolly mammoth has long been attributed to overhunting by early humans. However, recent evidence suggests that climate change was the primary driver. First, the warming climate at the end of the Pleistocene reduced the mammoth's preferred habitat—cold, dry steppe—by replacing it with forest and boggy tundra. This habitat loss would have drastically reduced food availability and population sizes. Second, genetic studies of mammoth remains show a severe population bottleneck around 20,000 years ago, well before human populations expanded significantly, indicating that climate stress, not hunting, triggered the decline. Third, archaeological sites from that period contain relatively few mammoth bones with clear cut marks, suggesting that humans did not rely heavily on mammoths as a food source. Instead, they hunted smaller, more abundant game. Thus, the timing and ecological patterns point to climate change as the main cause of the mammoth's demise.

🎧 リスニング講義

The reading's argument that climate change alone drove the woolly mammoth to extinction is flawed. While habitat did shrink, mammoths were highly adaptable and could survive in varied environments, as shown by their presence in regions with different climates. The genetic bottleneck cited actually occurred during a period when human hunting pressure was already intense in some areas, and such bottlenecks can also result from hunting, not just climate. Moreover, the scarcity of cut-marked bones is misleading: early humans often processed carcasses at kill sites away from their camps, and many bones may have been scavenged by carnivores, leaving few traces. In fact, recent findings at some sites show mammoth bones with tool marks, and human settlement patterns coincide with mammoth extinction timelines on different continents. Thus, overhunting by humans played a much larger role than the reading acknowledges.