The extinction of the woolly mammoth has long been attributed to overhunting by early humans. However, a closer examination of the evidence suggests that climate change was the primary driver. First, the timing of mammoth extinction aligns closely with the end of the last Ice Age, when global temperatures rose rapidly. This warming period, known as the Bølling-Allerød interstadial, caused dramatic shifts in vegetation, reducing the open grasslands that mammoths depended on. Second, genetic studies of ancient mammoth populations show a significant decline in genetic diversity long before human populations in the Arctic became substantial. This bottleneck suggests that environmental stress, not hunting pressure, was already taking a toll. Third, archaeological evidence for human hunting of mammoths is surprisingly sparse. Only a few sites contain clear kill sites or butchery marks, and these are often from periods when mammoths were already rare. In contrast, there is abundant evidence of humans hunting smaller, more accessible prey. Therefore, while humans may have delivered the final blow, the primary cause of mammoth extinction was climate-driven habitat loss.
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The reading's argument that climate change caused mammoth extinction is flawed. First, the timing argument is misleading. While temperatures did rise at the end of the Ice Age, mammoths had survived previous interstadial warming periods, such as the Eemian, which were even warmer. They only went extinct when humans with advanced hunting tools, like the Clovis points, arrived. Second, the genetic diversity decline cited in the reading actually supports human hunting. A decline in diversity can result from a population being fragmented and reduced by hunting pressure, not just environmental change. In fact, mammoth populations in isolated refugia, like Wrangel Island, persisted for thousands of years after the climate warmed, which contradicts the idea that habitat loss was fatal. Third, the claim that archaeological evidence for hunting is sparse is outdated. Recent excavations in Siberia and Alaska have uncovered mammoth bones with embedded projectile points and kill sites with mass accumulations of carcasses, indicating organized hunting. Moreover, the absence of extensive evidence may simply reflect the fact that many hunting sites are now submerged under the Bering Sea. Thus, the lecture argues that human predation, not climate, was the decisive factor.
📝 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.
