Escritura integrada TOEFL

📖 Texto de lectura

The extinction of the woolly mammoth, a species that roamed the Earth during the Pleistocene epoch, has long been attributed to human overhunting. However, a more recent and compelling theory suggests that climate change was the primary driver. This argument is supported by three main lines of evidence. First, the timing of mammoth extinctions across different regions correlates more strongly with major climatic shifts, such as the warming at the end of the last Ice Age, rather than with the arrival of human hunters. For instance, in Siberia, mammoth populations declined sharply during a period of rapid warming, while human presence was still sparse. Second, changes in vegetation due to climate warming would have drastically reduced the mammoth's primary food source. As grasslands gave way to forests and tundra, the open-steppe habitat that mammoths depended on disappeared, leading to nutritional stress and population decline. Third, genetic studies of fossil remains reveal a significant loss of genetic diversity in the last millennia before extinction, a sign of small, isolated populations struggling to survive, which is more consistent with a gradual environmental pressure than with sudden, localized human hunting. These points collectively argue that climate change, not human activity, was the decisive factor in the woolly mammoth's demise.

🎧 Conferencia de audio

The lecture challenges the idea that climate change alone caused the woolly mammoth's extinction, arguing that human hunting played a far more critical role. First, while climate shifts did occur, they were not unprecedented in the mammoth's long history. Mammoths had survived previous warming periods, which suggests that climate alone was not sufficient to drive them extinct. In contrast, the arrival of highly skilled human hunters on continents like North America coincided with rapid extinction events, a pattern seen in other megafauna as well. Second, the claim about vegetation change overlooks the fact that mammoths were adaptable feeders. Fossilized dung and stomach contents show that they consumed a variety of plants, including shrubs and herbs, not just grasses. This dietary flexibility would have allowed them to cope with some habitat changes. Third, the genetic diversity loss mentioned in the reading can be explained by human hunting. Selective hunting of large, healthy individuals would have reduced the breeding population, causing a genetic bottleneck. Also, human-driven habitat fragmentation, such as through fire, could have isolated populations, leading to inbreeding and eventual extinction. Thus, the lecture concludes that human activity, not climate, was the primary cause of the woolly mammoth's disappearance.