The extinction of the woolly mammoth, a species that roamed the Earth during the last Ice Age, has long been attributed to human hunting. However, a closer examination of the evidence suggests that climate change was the primary driver of their demise. First, the timing of the extinction coincides with a period of rapid warming at the end of the Pleistocene, roughly 10,000 to 12,000 years ago. As temperatures rose, the mammoth's preferred habitat—cold, dry grasslands—shrank dramatically, replaced by forests and wetlands that offered unsuitable forage. Second, genetic studies of mammoth remains show a significant decline in population size well before the arrival of large-scale human hunters in many regions, indicating that environmental stress, not hunting pressure, initiated the decline. Third, on isolated islands such as Wrangel Island, where mammoths survived until around 4,000 years ago, human presence was minimal or absent, yet the final extinction still occurred, likely due to inbreeding and reduced genetic diversity caused by shrinking island populations. Thus, while humans may have delivered a final blow in some areas, the overarching cause of the mammoth's extinction was climate-induced habitat loss and its cascading effects.
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The reading presents a compelling case for climate change as the main cause of the woolly mammoth's extinction, but this view is seriously flawed. First, the timing argument is misleading. While warming did occur, mammoths had survived previous interglacial warm periods, so temperature alone cannot explain their disappearance. Instead, the key factor was the arrival of highly skilled human hunters, whose populations expanded dramatically around 12,000 years ago—exactly when the final extinction occurred on the mainland. Second, the genetic evidence cited in the reading is misinterpreted. Population declines before human arrival were likely due to natural fluctuations, but these declines did not lead to extinction until humans appeared. In fact, mammoth populations rebounded during cooler periods, only to crash again when hunting intensified. Third, the case of Wrangel Island actually undermines the climate hypothesis. Mammoths there survived for thousands of years after the mainland extinction, thriving despite a small population. Their eventual extinction around 4,000 years ago coincides with the arrival of seafaring humans, who likely hunted them and introduced diseases. Thus, the evidence strongly supports human hunting as the primary cause, with climate playing only a secondary 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.
