The extinction of the woolly mammoth has long been attributed to human overhunting, but a closer examination of the fossil record and environmental data suggests that climate change was the primary driver. First, the timing of mammoth extinction correlates more strongly with the end of the last Ice Age (around 10,000 years ago) than with the arrival of human hunters. In North America, humans arrived at least 15,000 years ago, yet mammoths persisted for another 5,000 years, indicating that hunting pressure alone was insufficient to cause extinction. Second, the warming climate transformed the mammoth's preferred habitat—the dry, grassy steppe—into wetter, forested landscapes. Fossil pollen records show a rapid expansion of trees and shrubs exactly when mammoth populations declined, suggesting that mammoths lost their primary food source and open grazing grounds. Third, the extinction of other megafauna, such as the woolly rhinoceros and the giant beaver, also coincides with the same climatic shift, even though these species were not heavily hunted by humans. This pattern implies a common environmental cause rather than a human-specific impact. Therefore, while humans may have contributed locally, the overwhelming evidence points to climate-driven habitat loss as the decisive factor in the woolly mammoth's demise.
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The reading presents a tidy climate-change story, but it overlooks several critical pieces of evidence. First, the timing argument is flawed. While humans arrived in North America 15,000 years ago, they did not reach all mammoth habitats simultaneously. In the Arctic islands, where mammoths survived until 4,000 years ago, humans arrived only 500 years before their disappearance—a very tight correlation. This suggests that when humans finally reached these refuges, they delivered the final blow. Second, the habitat loss claim ignores the fact that mammoths were adaptable. Fossilized dung and tooth wear show that mammoths could browse on shrubs and trees when grasses were scarce. Indeed, populations in the Great Lakes region persisted for millennia in forested environments, indicating they were not solely dependent on steppe vegetation. Third, the reading's 'common extinction' argument fails to note differences in timing. Woolly rhinos vanished at the start of the warming, but giant beavers disappeared much later, during a period of cooling. This staggered extinction pattern is inconsistent with a single climatic event. In contrast, human hunting pressure, which varied by region and species, better explains these differential extinction dates. Thus, while climate change might have weakened mammoth populations, it was likely human hunting that delivered the final extinction blow.
📝 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.
