The extinction of the woolly mammoth has long been attributed to human overhunting, but recent evidence suggests that climate change was the primary driver. First, the timing of mammoth decline coincides with the rapid warming at the end of the last Ice Age (approximately 10,000 years ago), not with the arrival of human hunters, who had already coexisted with mammoths for thousands of years without causing significant population drops. Second, warming led to the replacement of dry, grassy steppes with wet, forested landscapes, which reduced the open grazing habitat that mammoths required. Fossil pollen and plant remains from this period show a dramatic shift to shrubs and trees, indicating a loss of their primary food source. Third, rising sea levels and increased precipitation created boggy terrain, which posed a fatal hazard for heavy animals like mammoths, as many fossilized remains have been found in waterlogged sediments, suggesting they drowned or became mired. Therefore, while humans may have delivered a final blow, climate-induced habitat loss and environmental stress were the decisive factors in their extinction.
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The reading's claim that climate change alone drove the woolly mammoth to extinction is unconvincing. First, human hunting pressure was not constant; rather, it intensified precisely as the climate warmed. Archaeological evidence shows that human populations expanded dramatically and developed more sophisticated weapons, including spears and traps, around 12,000 years ago. This increased hunting efficiency, combined with the fact that mammoth populations were already stressed by habitat changes, likely pushed them over the edge. Second, while vegetation did shift, mammoths were not strictly grazers. Isotopic analyses of mammoth bones and teeth reveal that they consumed a variety of plants, including woody browse, and could adapt to changing food sources. Modern elephants, their relatives, thrive in forested environments, so the habitat shift alone would not have caused extinction. Third, the boggy terrain argument is flawed because many large mammals, such as bison and horses, also lived in these environments and survived. In fact, mammoths had thick, padded feet and were capable of traversing wetlands. The presence of remains in sediments may simply reflect better preservation, not a cause of death. Thus, the most parsimonious explanation is that human hunting, in combination with environmental stress, was the critical factor, and the reading overstates the role of climate.
📝 写作提示 Summarize the points made in the lecture, being sure to explain how they cast doubt on the specific points made in the reading passage.
