การเขียนเชิงบูรณาการ TOEFL

📖 เนื้อเรื่อง

The extinction of the woolly mammoth has long been attributed to human overhunting, a theory supported by the timing of their disappearance and the presence of spear points at some sites. However, a more plausible cause is a combination of climate change and disease. First, the warming climate at the end of the Pleistocene reduced the mammoth's preferred habitat—cold, dry grasslands—by replacing them with forests and wetlands. This habitat loss would have fragmented populations and reduced food availability, leading to decline even without human interference. Second, mammoths may have been susceptible to infectious diseases carried by other herbivores that expanded their ranges as the climate warmed. For instance, tuberculosis-like pathogens have been found in ancient mammoth remains, suggesting that epidemics could have swept through already stressed populations. Third, human hunting was likely not intense enough to cause extinction, as evidence indicates that early human populations were small and their hunting tools were relatively crude, which would have made killing a full-grown mammoth difficult and dangerous. Thus, while humans may have contributed locally, the primary drivers of extinction were environmental and biological factors.

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The reading's argument that climate and disease drove mammoth extinction is unconvincing. First, while it is true that grasslands declined, mammoths were not solely dependent on cold grasslands. Fossil evidence shows that they also grazed on sedges and herbs in more varied environments, and they survived in different habitats, such as the Beringian steppe, which persisted longer than the reading claims. Moreover, the timing of their extinction does not align well with climate change; mammoths survived on remote islands like Wrangel Island for thousands of years after the climate warmed, which suggests that climate alone was not sufficient. Second, the disease hypothesis lacks direct evidence. The presence of pathogens in remains does not prove they caused mass mortality—many modern animals carry similar pathogens without epidemics. Additionally, for a disease to cause extinction, it would need a reservoir host and a high transmission rate, but there is no evidence of such a mechanism among mammoth populations. Third, the claim that human hunting was insufficient is flawed. Recent archaeological findings show that humans used sophisticated hunting techniques, including pits and drives, and mammoth bone piles at some sites indicate mass kills. Even low hunting pressure could have been devastating for a species with a slow reproductive rate, like mammoths, which had long gestation periods and single calves. Therefore, human overhunting remains the most parsimonious explanation.