การเขียนเชิงบูรณาการ TOEFL

📖 เนื้อเรื่อง

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 extinction coincides with a period of rapid warming at the end of the last Ice Age, around 10,000 years ago. As temperatures rose, the open grasslands that mammoths depended on were replaced by dense forests and wetlands, reducing their habitat and food supply. Second, genetic studies of mammoth remains show a significant decline in genetic diversity well before human populations expanded in their ranges. This suggests that populations were already shrinking due to environmental stress, not sudden human predation. Third, human hunting tools and kill sites from that era are relatively rare, and many human settlements were concentrated in coastal areas, not in the interior grasslands where mammoths thrived. Therefore, the evidence points to climate-driven habitat loss as the main cause of their extinction.

🎧 การบรรยาย

The lecture challenges the reading's claim that climate change, not humans, caused woolly mammoth extinction. First, while warming did alter habitats, mammoths were adaptable and had survived previous interglacial periods with similar temperature increases. In contrast, the arrival of sophisticated human hunters with projectile weapons and coordinated hunting strategies coincided exactly with their final disappearance on both continents. Second, the genetic diversity decline cited in the reading may reflect natural population fluctuations, not long-term stress. More importantly, the most severe genetic bottlenecks occurred after humans arrived, and rapid population crashes—typical of overhunting—are visible in the DNA record. Third, the scarcity of kill sites is misleading: mammoth bones with embedded spear points have been found, and many kill sites may be underwater or destroyed by glacial activity. Additionally, human settlements were not limited to coasts; inland sites with mammoth remains and butchering tools have been discovered. Thus, the evidence strongly supports human overhunting as the decisive factor.