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 correlates with the end of the last Ice Age, when global temperatures rose rapidly and caused dramatic shifts in vegetation. As grasslands gave way to forests and tundra, the mammoth’s primary food source—nutrient-rich grasses—became scarce, leading to population decline. Second, genetic studies of ancient mammoth remains reveal a severe loss of genetic diversity just before extinction, indicating that populations were already fragmented and vulnerable due to habitat loss, not sudden human predation. Third, archaeological records show that human hunting of mammoths was relatively rare compared to other megafauna, and human populations in the Arctic regions where mammoths thrived were sparse, making overhunting an unlikely cause. Thus, while humans may have delivered a final blow, climate-induced habitat change was the fundamental cause of the mammoth’s demise.

🎧 การบรรยาย

The reading’s claim that climate change alone drove woolly mammoth extinction is flawed. First, while climate did alter vegetation, similar warming events had occurred earlier in the Ice Age without causing extinction. What was different this time was the arrival of highly skilled human hunters with advanced tools, such as spears and organized hunting strategies. Second, the genetic bottleneck observed in mammoth populations could equally result from overhunting, which reduces population size and fragments groups, leading to inbreeding—a pattern seen in modern overexploited species. Third, archaeological evidence is incomplete; many early human settlements were likely near coastlines now submerged by rising seas, so we have not uncovered the full extent of hunting. Moreover, cave paintings and butchered mammoth bones at human sites indicate that hunting was more common than the reading suggests. Therefore, the lecture argues that human activity, in combination with climate stress, was the decisive factor, not climate alone.