托福综合写作

📖 阅读文章

The extinction of the woolly mammoth has long been attributed to human overhunting, but recent evidence suggests that climate change played a more decisive role. Proponents of the climate hypothesis point to three main arguments. First, the rapid warming at the end of the last Ice Age altered mammoth habitats, shrinking the open grasslands they depended on. Fossil pollen records show that these grasslands were replaced by forests and tundra, which offered less nutritious forage. Second, mammoth populations began to decline well before humans arrived in certain regions, such as Wrangel Island, where remains date to after human settlement but show signs of inbreeding and low genetic diversity. Third, extreme weather events, such as sudden thaws and heavy snowfall, could have created ice crusts that prevented mammoths from accessing vegetation, leading to starvation. These climatic pressures, rather than hunting, likely drove the species to extinction.

🎧 听力讲座

The lecture challenges the reading's claim that climate change was the primary cause of woolly mammoth extinction. While climate shifts did occur, the professor argues that human hunting was the decisive factor. First, the grassland-to-forest transition was not abrupt but gradual, occurring over millennia. During this time, mammoths could have adapted by shifting their diets, as evidenced by isotopic analyses of mammoth bones showing they consumed a wider range of plants in later periods. Second, the Wrangel Island example is misleading: although mammoths survived there until 4,000 years ago, their genetic decline was due to a small founder population, not climate. In fact, they coexisted with humans for over 700 years, and their extinction coincided with the arrival of new human groups with advanced hunting tools. Third, the alleged ice crusts are speculative; no direct evidence exists for such events causing mass starvation. In contrast, archaeological sites in North America and Eurasia show clear cut marks on mammoth bones, clustered at kill sites, indicating that humans actively hunted them. Thus, the reading's climate-only explanation overlooks the direct evidence of human impact.