The extinction of the woolly mammoth, which occurred approximately 4,000 years ago, has long been attributed primarily to human hunting. However, recent evidence suggests that climate change was the dominant factor. First, the warming climate at the end of the last Ice Age drastically reduced the mammoth’s habitat. As temperatures rose, vast grasslands known as the mammoth steppe were replaced by forests and wetlands, which were unsuitable for these large herbivores. Fossil pollen records show that this vegetation shift coincided with the mammoth’s decline. Second, climate change likely caused increased winter snowfall, which made it harder for mammoths to access vegetation beneath the ice. Isotopic analyses of mammoth bones reveal periods of nutritional stress during the warming phases. Third, the timing of extinction supports the climate hypothesis: mammoths survived on isolated Arctic islands, such as Wrangel Island, until much later than mainland populations, despite evidence of human presence there. This suggests that human hunting was not the primary driver, but rather the loss of suitable habitats due to climate change.
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The reading’s claim that climate change alone drove the mammoth’s extinction is not convincing. First, while climate change reduced grassland habitats, it did not eliminate them entirely. Large areas of suitable steppe remained in refugia, as shown by plant macrofossils in Siberia. Yet mammoths vanished from these very areas, which points to human overhunting rather than habitat loss. Second, the idea that snow cover prevented feeding is speculative. Modern elephants, close relatives of mammoths, can dig through snow and ice with their trunks and tusks. Moreover, isotopic stress in bones could result from other factors, such as competition with other herbivores or disease, not necessarily starvation due to snow. Third, the survival of mammoths on Wrangel Island actually undermines the climate argument. If climate were the main cause, why did a small island population persist for thousands of years longer than the mainland? The most plausible explanation is that humans did not arrive on Wrangel until much later, whereas they had already colonized the mainland. When humans finally reached the island, the mammoths quickly went extinct. Thus, human hunting, not climate, explains the pattern of extinction.
📝 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.
