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 grassland habitat. As temperatures rose, forests and tundra expanded, replacing the steppe-tundra that mammoths depended on for food. This habitat loss would have led to population decline regardless of human activity. Second, climate change altered migration patterns and breeding cycles. Warmer winters and shifts in seasonal weather likely disrupted the mammoths' ability to find mates and raise calves, leading to lower birth rates. Third, the timing of extinction aligns with major climatic events, not human expansion. Radiocarbon dating shows that mammoths survived on isolated islands like Wrangel Island until around 2000 BC, long after humans had arrived on mainland areas. On these islands, where climate was more stable, mammoths persisted—suggesting that climate, not humans, was the decisive factor.

🎧 リスニング講義

The reading's argument that climate change alone drove the woolly mammoth's extinction is flawed. First, while habitat change was significant, human hunting intensified the impact. Archaeological sites show that early humans actively hunted mammoths, using their bones for shelter and tools. Even if climate reduced mammoth numbers, human predation could have pushed already stressed populations over the edge. Second, the claim about disrupted breeding is speculative. Modern elephants, close relatives, breed successfully in varied climates, and there is no direct evidence that mammoth birth rates declined due to warming. In fact, fossil records indicate stable populations during earlier warm periods, suggesting they could adapt. Third, the Wrangel Island example actually supports the human overhunting theory. Mainland mammoths went extinct about 10,000 years ago, coinciding with the arrival of advanced human hunters. Wrangel Island, being remote and small, likely escaped human contact until much later. When humans finally reached the island around 2000 BC, mammoths disappeared within a few centuries. This pattern—extinction following human arrival—is consistent across many large animal species, whereas climate change alone does not explain the timing.