TOEFL Integrated Writing

📖 Reading Passage

The extinction of the woolly mammoth has long been attributed to overhunting by early humans. However, recent research suggests that climate change was the primary driver. First, the warming period at the end of the Pleistocene reduced the mammoth’s preferred habitat—cold, dry steppe—by replacing it with forests and wetlands. As these grasslands shrank, mammoth populations fragmented and declined. Second, isotopic analysis of mammoth bones reveals that, in the millennia before extinction, their diets shifted to less nutritious plants, indicating habitat stress rather than sustained hunting pressure. Third, the timing of extinction correlates more closely with rapid climate fluctuations, such as the Younger Dryas, than with the arrival of human hunters. For example, mammoths survived on Wrangel Island until 4,000 years ago, long after humans arrived, but their final demise coincided with a period of extreme climatic instability. Thus, while hunting may have contributed locally, climate-driven habitat loss was the decisive factor.

🎧 Listening Lecture

The reading’s claim that climate change drove mammoth extinction is unconvincing. First, the habitat-shrinkage argument ignores that mammoths were adaptable. Fossil pollen records show that some mammoth populations thrived in boreal forests and even tundra-forest ecotones, not solely on steppe. Second, the isotopic data cited actually reflect a change in food availability, but this could be due to competition from other herbivores or even human-induced landscape burning, not purely climate. More importantly, archaeological sites reveal clear evidence of mammoth butchery, with spear points embedded in bones and kill sites dating to exactly the period of final extinction on the mainland. If climate were the main cause, we would expect a gradual decline across all regions. Instead, extinction was rapid and coincided with human expansion into Siberia and North America. Third, the Wrangel Island example actually undermines the climate argument: mammoths survived there through severe climatic changes, and their extinction at 4,000 years ago matches the arrival of humans on the island, not a major climate event. Thus, human hunting—not climate—was the primary cause.