The extinction of the woolly mammoth has long been attributed to human overhunting. However, recent evidence suggests that climate change was the primary driver. First, the warming period at the end of the Pleistocene drastically reduced the mammoth’s habitat. As glaciers retreated, the vast steppe-tundra grasslands—the mammoth’s main food source—were replaced by forests and wetlands, shrinking their range and fragmenting populations. Second, climate change caused increased precipitation and snowfall, creating ice layers that made it difficult for mammoths to access vegetation during winter. This reduced their nutritional intake and reproductive success. Third, the timing of extinction aligns more closely with rapid climate shifts than with human arrival. For example, mammoths survived on isolated islands like Wrangel Island until around 2000 BCE, long after humans had arrived, but only after the climate had already changed. Thus, while humans may have contributed locally, climate change was the decisive factor in the mammoth’s global extinction.
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The lecture challenges the reading’s claim that climate change alone drove the woolly mammoth to extinction. While it is true that habitat changed, the reading overlooks the role of human hunting. First, the reduction in steppe-tundra was not uniform; large patches remained in northern refugia, such as parts of Siberia and Alaska, where mammoths could have survived. Yet these areas saw the most intense human hunting pressure, as evidenced by massive kill sites and mammoth bone remains with cut marks. Second, the claim about ice layers preventing access to food is speculative. Modern elephants, close relatives, can break through thin ice with their tusks, and mammoths likely could too. Moreover, mammoth remains from the late Pleistocene show no signs of malnutrition, contradicting the idea of food scarcity. Third, the timing argument is misleading. Human arrival in many regions coincided closely with mammoth decline, and the Wrangel Island population survived only because it was small and isolated, not because climate was benign. When humans finally reached Wrangel Island, the mammoths disappeared within a few centuries. Therefore, hunting, not climate, was the primary cause 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.
