The extinction of the woolly mammoth has long been attributed to human overhunting, but recent evidence suggests that climate change was the primary driver. First, the timing of mammoth decline correlates closely with the end of the last Ice Age, when global temperatures rose rapidly. As the ice retreated, the steppe-tundra habitat that mammoths depended on shrank dramatically, replaced by forests and wetlands. This loss of grazing land would have reduced food availability, leading to malnutrition and population crashes. Second, genetic studies of ancient mammoth remains show a significant loss of genetic diversity just before extinction, indicating small, isolated populations that were vulnerable to inbreeding and disease. This pattern is more consistent with habitat fragmentation than with sudden human hunting pressure. Third, human populations at the time were small and widely scattered, with limited hunting technology. Even if they occasionally killed mammoths, their numbers were insufficient to drive a species to extinction across three continents. In contrast, climate-driven environmental change was a global phenomenon that could affect all mammoth populations simultaneously. Therefore, while humans may have delivered the final blow to already weakened populations, the ultimate cause was climate-induced habitat loss.
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The reading's claim that climate change alone drove mammoth extinction is not supported by the evidence. First, while it is true that the last Ice Age ended around 10,000 years ago, mammoths survived for thousands of years after the warming began in some regions, such as Wrangel Island, where they persisted until about 4,000 years ago. This shows that climate change did not inevitably kill them—other factors must have been at play. Second, the genetic diversity loss cited in the reading can actually be explained by human hunting. When humans arrived in a region, they often targeted the largest individuals, which were also the most genetically diverse. This selective hunting would have reduced genetic variation over time, not habitat fragmentation. Moreover, isolated populations on islands like Wrangel still had enough genetic diversity to survive for 6,000 years, so low diversity alone was not fatal. Third, the reading underestimates human impact. Archaeological sites show that mammoth bones were used to build shelters and tools, indicating that humans hunted them intensively. Also, human populations were growing and spreading rapidly during the late Pleistocene, and their hunting efficiency improved with new weapons like the atlatl. In fact, the timing of mammoth extinction on different continents matches the arrival of modern humans, not just temperature changes. Thus, the lecture argues that human hunting, not climate, was the decisive factor.
📝 작문 지시 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).
