Escritura integrada TOEFL

📖 Texto de lectura

The extinction of the woolly mammoth at the end of the Pleistocene epoch has long been attributed to human overhunting. However, a more plausible explanation is climate change, which drastically altered the mammoth’s habitat. First, the warming climate caused the replacement of open steppe-tundra with dense forests and wetlands, reducing the grazing areas that mammoths depended on. This habitat loss would have led to population fragmentation and decline, independent of human activity. Second, climate change disrupted the mammoth’s reproductive cycle. Studies of ancient mammoth remains show that periods of rapid warming coincided with lower calf survival rates, likely due to nutritional stress on pregnant females. This demographic effect would have been severe even without hunting pressure. Third, the timing of mammoth extinction does not align with human arrival in many regions. For example, on Wrangel Island, mammoths survived until about 4,000 years ago, long after humans arrived, but they disappeared shortly after a period of dramatic climate fluctuation. Thus, the evidence strongly suggests that climate change, not hunting, was the primary driver of mammoth extinction.

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The reading's argument that climate change alone drove mammoth extinction is unconvincing. While it is true that warming altered habitats, mammoths were highly adaptable and had survived previous interglacial periods with similar conditions. Their extinction only occurred when humans were present, which suggests a synergistic effect. For instance, on Wrangel Island, mammoths did survive until 4,000 years ago, but that was a dwarf population isolated on a small island. When humans arrived there, the population was already vulnerable due to limited genetic diversity, and hunting likely delivered the final blow. Regarding reproductive issues, the reading cites calf survival declines, but these correlates do not prove causation. In fact, during the same warm periods, other large herbivores like bison and horses thrived, indicating that climate was not universally detrimental. Moreover, archaeological sites show clear evidence of mammoth butchery, with spear points embedded in bones and kill sites dating to the exact period of extinction. The most parsimonious explanation is that human hunting, perhaps combined with climate stress, pushed mammoths over the edge. Therefore, the reading's attempt to dismiss human impact overlooks the direct evidence of hunting and the unique vulnerability of mammoths to human predation.