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 decline correlates with the end of the last Ice Age, when global temperatures rose rapidly. As the climate warmed, the mammoth's preferred habitat—cold, dry steppe grasslands—shrank dramatically, replaced by forests and wetlands that offered poor forage. Second, genetic studies show that isolated mammoth populations, such as those on Wrangel Island, survived for thousands of years after human arrival, indicating that humans were not the sole cause. Finally, the extinction of other megafauna, like the giant sloth, also coincided with climate shifts, not just human colonization, suggesting a common environmental cause.
🎧 听力讲座
The professor argues that the reading's climate-based explanation is flawed. While temperature rose, the key factor was human hunting pressure on already stressed populations. First, the correlation with climate is misleading: mammoths survived previous interglacial warm periods, so warming alone wasn't fatal. Instead, the combination of habitat loss and new, efficient human hunters—who used spears and drove herds off cliffs—proved overwhelming. Second, the Wrangel Island population actually shows the opposite: those mammoths were genetically weakened by inbreeding, and they died out only when humans arrived on the island, not during a climate shift. Third, the comparison with giant sloths is weak because sloths were hunted in different ways and their extinction timeline does not perfectly match climate events; moreover, many areas where sloths vanished had stable climates but active human hunting. Thus, the lecture concludes that overhunting, not climate, was the decisive factor.
📝 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.