The extinction of the woolly mammoth has long been attributed to human overhunting. However, a closer examination of the evidence suggests that climate change was the primary driver. First, the timing of mammoth extinctions correlates more strongly with periods of rapid warming than with human arrival. In North America, mammoths disappeared around 10,000 years ago, during a period of significant temperature rise, whereas humans had been present for at least 2,000 years before that. Second, the habitat of mammoths—cold, dry grasslands known as the mammoth steppe—shrank dramatically as warming led to the expansion of forests and wetlands. This habitat loss would have reduced the available food and shelter, making mammoth populations vulnerable. Third, genetic studies of mammoth remains show a decline in genetic diversity well before human populations became large, indicating that populations were already struggling due to environmental stress, not hunting pressure. Therefore, climate change, not humans, was the main cause of their demise.
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The reading's argument that climate change alone drove mammoth extinction is flawed. While warming did alter habitats, humans played a critical, synergistic role. First, the correlation between warming and extinction is not as clear as claimed. In some regions, such as Wrangel Island, mammoths survived for thousands of years after the warming period, until humans arrived around 4,000 years ago. This suggests that human presence was the final trigger. Second, habitat changes alone cannot explain why other large herbivores, like bison and horses, survived the same warming period by adapting to new vegetation. Mammoths, with their specialized diet, were more vulnerable, but they still could have persisted if not for hunting. Third, the genetic decline cited in the reading may reflect natural population fluctuations, not impending extinction. Indeed, similar declines are seen in species that later recovered. Moreover, archaeological sites show clear evidence of mammoth hunting, including spear points embedded in bones and butchery marks. Thus, human hunting, combined with climate stress, was decisive, but the reading wrongly dismisses the human role.
📝 写作提示 Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
