TOEFL Integrated Writing

📖 Reading Passage

The extinction of the woolly mammoth has long been attributed to overhunting by early humans. However, recent evidence suggests that climate change played a more decisive role. First, the warming climate at the end of the Pleistocene reduced the mammoth’s preferred habitat—cold, dry steppe—by allowing forests and wetlands to expand. Fossil pollen records from Siberia and Alaska show a dramatic shift from grasses to shrubs and trees, which would have reduced the mammoth’s food supply. Second, the mammoth’s thick coat and small ears were adaptations to extreme cold, making them poorly suited to warmer, wetter conditions. As temperatures rose, mammoths likely suffered from heat stress and increased susceptibility to disease. Third, human population densities were too low at the time to have caused extinction, as archaeological sites with mammoth remains are rare and widely scattered, suggesting that hunting was sporadic rather than systematic. Therefore, climate-driven habitat loss and physiological stress, not human hunting, were the primary causes of the mammoth’s demise.

🎧 Listening Lecture

The reading’s claim that climate change alone drove the woolly mammoth to extinction is not convincing. First, while it is true that vegetation changed, mammoths were not strictly dependent on steppe grasses. Isotopic analysis of mammoth bones from the late Pleistocene shows that they consumed a varied diet, including shrubs and sedges, which remained available even as forests expanded. Thus, food scarcity was not a fatal issue. Second, the idea that mammoths were too specialized for warm climates is contradicted by evidence from Wrangel Island, where a dwarf mammoth population survived for thousands of years after the main extinction event, despite a warmer and wetter climate. These animals thrived in conditions similar to those that supposedly killed their mainland relatives. Third, the archaeological record is biased: many coastal sites where humans lived are now submerged due to sea-level rise, so we have likely underestimated human presence. In fact, recent finds in Siberia show mammoth bones with clear cut marks and spear points, indicating active hunting. When humans first arrived in Siberia around 30,000 years ago, mammoth populations began to decline sharply, a pattern that matches overhunting. Thus, the evidence points to human hunting as the primary driver, not climate.