The extinction of the woolly mammoth has long been attributed to human hunting, but recent evidence suggests that climate change was the primary driver. First, the timing of mammoth decline correlates closely with the warming period at the end of the last Ice Age, around 10,000 years ago. As temperatures rose, their grassland habitats shrank, replaced by forests and tundra, reducing their food supply. Second, genetic studies show that mammoth populations experienced severe bottlenecks long before humans reached their main habitats in Siberia and North America, indicating that climate-induced habitat fragmentation was already stressing populations. Third, human hunting pressure was likely too low to cause extinction, as estimates of human population density in these regions were sparse, and archaeological evidence of mammoth kills is rare compared to other megafauna. Thus, while humans may have delivered a final blow, climate-driven environmental change was the fundamental cause of their demise.
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The reading's claim that climate change alone drove mammoth extinction is unconvincing. First, the correlation with warming is misleading; similar warming periods occurred earlier in the Pleistocene without causing extinction, so climate alone cannot explain why mammoths vanished only when humans were present. Second, the genetic bottlenecks cited actually reflect population declines that coincide with human expansion, not just habitat change. In fact, recent DNA analysis reveals that the final survivors on Wrangel Island persisted for thousands of years after the climate stabilized, implying that climate was not the limiting factor—rather, human arrival on the island likely triggered their collapse. Third, the argument about low hunting pressure ignores that humans did not need to kill many mammoths to cause extinction; even moderate hunting of a slow-reproducing species, combined with human-caused habitat modification through fire, could have tipped populations over the edge. Moreover, the rare kill sites may simply reflect poor preservation, as many carcasses were scavenged or lost. Therefore, human activities, not climate, were 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.
