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 with the end of the last Ice Age, when global temperatures rose rapidly. As the planet warmed, the steppe-tundra habitat that mammoths relied on shrank dramatically, replaced by forests and wetlands that offered poor forage. Second, genetic studies of fossil remains show that mammoth populations experienced severe bottlenecks before significant human expansion into their ranges. In Arctic regions like Wrangel Island, isolated mammoths survived for thousands of years after humans arrived, but they eventually died out during a period of climatic instability. Third, archaeological evidence indicates that human hunting was not intensive enough to cause extinction. Sparse kill sites and low human population densities in Siberia and North America suggest that hunting pressure was minimal, whereas climate-driven habitat loss would have reduced food availability and reproductive success simultaneously. Therefore, while humans may have delivered the final blow to some populations, the overarching cause of mammoth extinction was environmental change.
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The reading's argument is flawed. While climate change did alter mammoth habitats, it was not the primary cause of extinction. First, the correlation between warming and habitat shrinkage is misleading. During earlier interglacial periods, mammoths also experienced warm climates and habitat shifts, yet they survived for hundreds of thousands of years. The key difference in the late Pleistocene was the arrival of highly skilled human hunters who used advanced weapons and coordinated drives. Second, the genetic bottlenecks cited in the reading actually support the overhunting hypothesis. Small, isolated populations on islands like Wrangel were highly vulnerable to any hunting pressure, and even minimal human predation could have tipped them into extinction. Moreover, the timing of these bottlenecks coincides with human colonization of those islands, not just climatic events. Third, the claim that hunting was sparse is based on incomplete evidence. Many kill sites are now submerged due to sea-level rise, and early human populations may have been larger than previously thought, as recent finds in Arctic regions suggest. In fact, human-driven extinction is consistent with the pattern seen in other megafauna, such as the giant ground sloth, which disappeared shortly after humans arrived. Thus, the reading overlooks the decisive role of human activity.
📝 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.
