Escritura integrada TOEFL

📖 Texto de lectura

The extinction of the woolly mammoth has long been attributed to human hunting, but recent evidence suggests that climate change was the primary driver. First, the timing of mammoth extinction coincides with the end of the last Ice Age, when global temperatures rose rapidly. Paleoclimatic data show that as temperatures increased, the steppe-tundra habitat that mammoths depended on shrank dramatically, being replaced by forests and wetlands. Second, genetic studies of mammoth remains reveal a severe population bottleneck around 20,000 years ago, well before humans arrived in large numbers in Siberia and North America. This decline aligns with a period of climatic instability, not with human hunting pressure. Third, archaeological evidence indicates that early human hunters primarily targeted smaller, easier prey, such as reindeer and bison. Mammoth bones found at human sites are often scarce and appear to be scavenged from natural deaths rather than from active hunts. Therefore, while humans may have delivered the final blow to isolated populations, the overarching cause was climate-induced habitat loss.

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The reading's argument that climate change caused mammoth extinction is flawed. First, although temperatures rose at the end of the Ice Age, similar warming events had occurred before, yet mammoths survived. For example, during the Eemian interglacial, temperatures were even warmer, and mammoths thrived. Thus, habitat change alone cannot explain their extinction. Second, the genetic bottleneck cited in the reading actually occurred around 20,000 years ago, but this was a period of intense cold, not warming. During this time, humans had already been present in Siberia for thousands of years, and their hunting pressure, combined with cold stress, could have reduced mammoth populations. The reading ignores this human presence. Third, the claim that humans avoided mammoth hunting is contradicted by recent findings from sites like Clovis, where spear points have been found embedded in mammoth ribs. Additionally, stable isotope analysis of human remains from the period shows a diet rich in mammoth meat. These direct indicators of hunting undermine the reading's assumption that humans only scavenged. Therefore, human predation, not climate, was the decisive factor in the mammoth's demise.