การเขียนเชิงบูรณาการ TOEFL

📖 เนื้อเรื่อง

The extinction of the woolly mammoth has long been attributed to overhunting by early humans, but recent evidence suggests that climate change was the primary driver. First, the timing of mammoth decline correlates with the warming period at the end of the last Ice Age, around 10,000 years ago, when vast grasslands shrank and were replaced by forests and tundra. This habitat loss would have drastically reduced the mammoth's food supply and living space. Second, genetic studies of ancient mammoth remains show a significant loss of genetic diversity before their final extinction, indicating that populations were already stressed by environmental pressures, not sudden human hunting pressure. Finally, human populations in Siberia and North America during that period were sparse and relied primarily on smaller game, as evidenced by archaeological sites that contain few mammoth bones; thus, human hunting was unlikely to be intense enough to cause extinction.

🎧 การบรรยาย

The lecture challenges the idea that climate change alone drove woolly mammoths to extinction. While the warming trend did shrink grasslands, similar climatic shifts had occurred earlier in the mammoth's history, and the species survived those changes. For instance, during previous interglacial warm periods, mammoths adapted by migrating northward or altering their diets, so habitat change alone was not fatal. Furthermore, the loss of genetic diversity cited in the reading can be explained by human hunting: as humans selectively targeted the largest individuals for their tusks and meat, they reduced the breeding population and disrupted social structures, leading to inbreeding and genetic decline—not as a pre-existing condition but as a direct consequence of human activity. Finally, the archaeological evidence is misleading because early human sites near mammoth remains often show butchery marks, and many kill sites have been submerged or destroyed by rising sea levels after the Ice Age. Thus, the scarcity of mammoth bones at some sites does not rule out significant hunting pressure, especially in coastal regions where humans likely concentrated.