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 extinction coincides with the end of the last Ice Age, when global temperatures rose rapidly. This warming caused dramatic shifts in vegetation, replacing the vast steppe grasslands—the mammoth’s primary food source—with forests and tundra, which could not support large herds. Second, archaeological evidence shows that human hunting pressure was relatively low. Sparse kill sites and the absence of specialized mammoth-hunting tools in many regions indicate that humans did not rely heavily on mammoths for subsistence. Finally, isolated populations survived on islands like Wrangel Island for thousands of years after humans arrived, but they eventually died out during a period of rapid environmental change, suggesting that habitat loss, not hunting, was the decisive factor.

🎧 リスニング講義

The lecture challenges the view that climate change alone caused mammoth extinction, arguing that human hunting played a crucial role. First, while climate change did alter vegetation, the shift was gradual, and mammoths had adapted to environmental changes before. In contrast, the arrival of modern humans, who were skilled hunters, coincided with rapid mammoth declines on multiple continents. Second, the archaeological record is biased; many kill sites may be underwater or undiscovered, and humans likely used wooden spears that decayed, leaving no trace. Recent finds in Siberia show butchered mammoth bones with cut marks, indicating sustained hunting. Third, the Wrangel Island example actually supports hunting pressure: those mammoths were dwarfed and vulnerable, and when humans colonized the island, they hunted them to extinction within a few centuries—a pattern seen in other island megafauna. Thus, the lecture argues that human predation, not climate, was the primary cause.