The extinction of the woolly mammoth, which occurred roughly 4,000 years ago, has long puzzled scientists. While climate change is often cited as a factor, a more compelling explanation is overhunting by early human populations. Three lines of evidence support this view. First, the timing of mammoth extinction coincides with the expansion of human hunters across Eurasia and North America. Radiocarbon dating shows that mammoth populations collapsed shortly after humans arrived in each region, a pattern consistent with a 'blitzkrieg' hunting model. Second, archaeological sites, such as the Clovis culture in North America, contain abundant mammoth bones with cut marks and embedded projectile points, indicating that humans actively hunted and butchered these animals. Third, stable isotope analysis of mammoth tusks from the late Pleistocene reveals a narrowing of their dietary niche, suggesting that populations were stressed and fragmented, which would have made them more vulnerable to hunting pressure. Together, these points argue that human predation, not climate, was the primary driver of the mammoth's demise.
🎧 听力讲座
🎯 模拟考试环境：先点「播放讲座」听完内容，再作答。听力原文默认隐藏。
The reading's claim that humans caused the woolly mammoth's extinction is not convincing. Consider the timing argument: while humans did arrive in some regions before mammoth disappearance, in other areas, such as Wrangel Island, mammoths survived for thousands of years after human contact. This contradicts a simple overhunting model. As for the archaeological evidence, cut marks on bones are rare and often ambiguous; they might result from scavenging carcasses of animals that died naturally, rather than active hunting. Moreover, many Clovis sites show evidence of only juvenile or sickly individuals, which is not typical of a healthy population being systematically wiped out. Finally, the isotopic narrowing cited as evidence of stress can be explained by climate-driven habitat fragmentation, which reduced the variety of forage plants. This same climate change also altered vegetation patterns, reducing the open grasslands mammoths depended on. Therefore, the evidence better supports climate change as the primary cause, with humans playing only a minor role.
📝 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.
