托福综合写作

📖 阅读文章

The extinction of the woolly mammoth has long been attributed to human overhunting. However, new evidence suggests that climate change, specifically a rapid warming period called the Bølling-Allerød interstadial, was the primary driver. First, the timing of mammoth decline coincides more closely with climate shifts than with human migration. Radiocarbon dating of mammoth remains in North America shows a sharp population drop around 14,000 years ago, exactly when temperatures rose dramatically, whereas human hunters arrived earlier but did not cause a similar crash. Second, the warming climate altered mammoth habitats. As ice sheets retreated, vast areas of open steppe—the mammoth’s preferred grazing land—were replaced by dense forests and wetlands, which provided less nutritious forage and increased vulnerability to predators. Fossilized plant remains from this period show a rapid transition from grassland to woodland, matching the mammoth’s decline. Third, mammoth physiology was poorly suited to warm climates. Their thick fur, small ears, and high body fat, which were adaptations for cold, would have caused overheating and heat stress during warmer summers, leading to reduced fertility and higher infant mortality. Together, these three lines of evidence—timing, habitat loss, and physiological constraints—strongly support climate change as the main cause of mammoth extinction, not human hunting.

🎧 听力讲座

The reading’s claim that climate change alone drove mammoth extinction is unconvincing. First, the timing argument is flawed. While mammoth numbers did decline around 14,000 years ago, human hunters had already been present for thousands of years, and archaeological sites show increasing use of mammoth bones and tusks for tools and shelter, indicating sustained hunting pressure. Moreover, mammoth populations survived earlier warm periods, such as the Eemian interglacial, without going extinct, so warmth alone cannot explain their demise. Second, the habitat change argument ignores evidence that mammoths were adaptable. Pollen and plant fossil records from some regions show that mammoths thrived in mixed woodland and grassland edges, not just open steppe. In addition, human-set fires may have accelerated habitat fragmentation, making the landscape less suitable for mammoths—a human-induced factor. Third, the physiological argument is overstated. Modern elephants, which are close relatives, live in warm climates without overheating, and mammoth fossils show they had sweat glands and behavioral adaptations, such as migrating to cooler highlands or rivers. In fact, the last known mammoth populations survived on Wrangel Island, where the climate was cold, until about 4,000 years ago—long after humans arrived elsewhere—suggesting that human hunting, not warming, was the critical factor in their final extinction.