托福综合写作

📖 阅读文章

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 extinctions on different continents correlates more closely with major climatic shifts than with human arrival. For instance, on Wrangel Island, mammoths survived until 2000 BCE, long after humans arrived, but disappeared shortly after a dramatic cooling event. Second, genetic studies of late-surviving mammoth populations reveal low genetic diversity and signs of inbreeding, indicating that populations were already stressed before human contact became significant. This fragility would have made them vulnerable to environmental changes, not to hunting pressure from sparse human populations. Third, archaeological sites show that humans primarily hunted smaller game and used mammoth bones and tusks mainly from already dead animals, suggesting that mammoths were not a primary food source. Therefore, while humans may have delivered a final blow, the extinction was fundamentally caused by climate-induced habitat loss and population fragmentation.

🎧 听力讲座

The reading's claims about climate change are misleading. First, the correlation between climate shifts and mammoth extinction is weak; on Wrangel Island, the supposed cooling event occurred after mammoth remains cease, and other islands with similar climates retained mammoths longer. In fact, human arrival on Wrangel Island around 2000 BCE coincides exactly with the last mammoth, and no other major climate anomaly is recorded. Second, low genetic diversity is common in many species that survived to modern times, such as the cheetah, and does not imply imminent extinction. Moreover, mammoth populations had been fluctuating for thousands of years, and the final crash occurred only when humans with advanced hunting tools arrived. Third, the archaeological record is biased: humans likely consumed mammoth meat on site, leaving few bones, whereas bones used for tools were transported away. Recent kill sites with spear points embedded in mammoth skeletons prove active hunting. Thus, the evidence points to human overhunting as the decisive factor, not climate change.