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 period at the end of the Pleistocene reduced the mammoth’s preferred habitat—cold, dry steppe—by replacing it with dense forests and wetlands. As a result, mammoth populations became fragmented and isolated, leading to reduced genetic diversity and lower reproductive success. Second, climate change altered the availability of food. The shift to warmer, wetter conditions favored plants that were less nutritious or digestible for mammoths, such as conifers and mosses, causing malnutrition and population decline. Finally, the timing of human arrival in North America does not align with mammoth extinction. In many regions, humans coexisted with mammoths for thousands of years before their disappearance, and archaeological evidence of mammoth hunting is scarce, suggesting that hunting pressure was insufficient to cause extinction. Thus, climate change, not human predation, was the decisive factor.
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The reading argues that climate change caused woolly mammoth extinction, but this view is flawed. First, while warming did alter habitats, it did not uniformly eliminate steppe. Large areas of northern Siberia and Alaska remained as open grassland during the early Holocene, and mammoth populations thrived there long after the climate warmed. Moreover, the fragmentation idea is contradicted by genetic studies showing that late mammoth populations had high genetic diversity, not the low diversity expected from isolation. Second, the claim about food quality is unsubstantiated. Fossilized mammoth dung and stomach contents reveal that they consumed a variety of plants, including grasses and sedges that remained abundant even as climate changed. There is no evidence that they starved due to lack of nutritious forage. Third, the timing argument is misleading. When humans arrived in North America, they did not have advanced weapons, but they hunted mammoths opportunistically, and even low-level hunting could have driven a slow-breeding species to extinction. In addition, on isolated islands like Wrangel Island, where humans arrived later, mammoths survived until about 4,000 years ago, but once humans settled there, they disappeared within a few centuries. This pattern strongly implicates human hunting as the final cause.
📝 Инструкция по письму Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
📊 TOEFL Integrated Writing Rubric
Content Accuracy: Accurately capture the relationship between lecture and reading
Information Completeness: Cover all key counter-arguments from the lecture
Structure & Coherence: Logical organization and progression
Language Use: Grammar, vocabulary, expression accuracy
Scored 0-30 based on holistic scoring (original 0-5, scaled to 30).
