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 climate at the end of the Pleistocene reduced the mammoth's grassland habitat. As temperatures rose, forests and tundra expanded, shrinking the open steppe where mammoths thrived. Second, genetic studies show that mammoth populations experienced a severe decline before the arrival of large-scale human hunting. DNA analysis indicates a bottleneck around 20,000 years ago, likely due to rapid climate fluctuations. Third, the timing of final extinctions on isolated islands, such as Wrangel Island, correlates with dramatic sea-level rise, not human colonization. These islands maintained dwarf mammoths until about 4,000 years ago, when post-glacial environmental changes became too extreme.
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The lecture challenges the idea that climate change alone caused woolly mammoth extinction. First, while grasslands did shrink, mammoths were adaptable. Fossil evidence shows they could survive on a variety of vegetation, including shrubs and herbs, and their range shifted rather than disappeared. Second, the genetic bottleneck cited actually coincides with an increase in human population and hunting pressure, not just climate. Moreover, mammoths had survived many previous climate changes, including warmer interglacials, without going extinct. Third, the Wrangel Island case is misleading: those mammoths persisted for thousands of years after sea-level rise, and their extinction around 4,000 years ago matches the arrival of humans on the island. Archaeological sites show human presence and butchered mammoth bones. Thus, while climate stress may have weakened populations, human hunting was the decisive factor in their final demise.
📝 Instrucciones de escritura 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).
