The extinction of the woolly mammoth at the end of the Pleistocene has long been attributed to human overhunting. However, a more comprehensive explanation involves climate change and habitat loss. Three key points support this view. First, climate warming after the last ice age drastically reduced the open grassland steppe that mammoths depended on, replacing it with forest and tundra. Pollen records from Siberia and Alaska show a rapid shift to birch and spruce forests around 10,000 years ago, coinciding with mammoth decline. Second, mammoth populations were already in decline before humans arrived in many regions. For example, on Wrangel Island, dwarf mammoths survived until 4,000 years ago, long after human presence, suggesting that isolation and small population size, not hunting, were the final causes. Third, the timing of extinction varies widely across regions, from 10,000 years ago in mainland Eurasia to 4,000 years ago on islands, which does not match a uniform human hunting pressure. Instead, it parallels local vegetation changes. Thus, climate-driven habitat loss is the primary driver.
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The reading claims that climate change, not human hunting, drove mammoths to extinction, but this argument has serious flaws. First, while it is true that grasslands shrank, mammoths were not strictly grassland specialists. Fossil evidence indicates they also consumed leaves and twigs from shrubs and trees, so the spread of forests does not necessarily mean starvation. In fact, mammoth remains are found in areas with mixed vegetation. Second, the Wrangel Island example is misleading. Those mammoths were a relict population that survived because the island was isolated, but they ultimately vanished around 4,000 years ago. Archaeological evidence shows that humans arrived on the island shortly before their extinction, and the mammoths show signs of overhunting, such as butchering marks. Third, the varied extinction dates actually support human hunting: humans migrated to different regions at different times, and in each case, mammoth extinction followed within a few centuries. For example, in North America, mammoths disappeared about 1,000 years after Clovis hunters appeared. The correlation is too strong to ignore. Therefore, human activity, not climate, is the more plausible cause.
📝 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.
