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作者:寄托家园作文版普通用户 共用时间:30分1秒 331 words
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Humans arrived in the Kaliko Islands about 7,000 years ago, and within 3,000 years most of the large mammal species that had lived in the forests of the Kaliko Islands had become extinct. Yet humans cannot have been a factor in the species' extinctions, because there is no evidence that the humans had any significant contact with the mammals. Further, archaeologists have discovered numerous sites where the bones of fish had been discarded, but they found no such areas containing the bones of large mammals, so the humans cannot have hunted the mammals. Therefore, some climate change or other environmental factor must have caused the species' extinctions.
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In the argument, the author asserts that the extinctions of the large mammal species result from climate change or other environmental factors. To support his assertion, the author cites some archaeological discoveries. At the first glance, the argument seems persuasive; however, careful scrutiny will reveal several flaws in the analysis.
In the first place, lack of evidence should not be considered as evidence to illustrate that humans have no significant contact with the mammals. Further research on archaeology and history might provide more information suggesting significant contact did exist. Even if there are not direct contact between humans and mammals, human activities can also have great influence on their extinction indirectly. For example, human activities might disturb the food chain of the mammals. Perhaps those mammals live solely on fish, whose population decreased significantly due to humans' hunting.
In the second place, the archaeologists’ discovery cited in the essay cannot sustain the author’s conclusion either. Although there are no bones of large mammals found at the sites, it does not follow that humans had not hunted the mammals. As is known to all, the bones of large animals are usually cherished by ancient people, who used them as knives, needles as well as decorations. That might be the true reason why none bones of large mammals was found.
Last but not the least; the author ignores many other factors contributing to the extinctions of the mammals except climate change or environmental factor. Maybe it was some kinds of contagions that killed all the animals in a short time. Moreover, the fire, produced by humans might be another important reason for the extinction in that nearly all the animals are afraid of fire.
To sum up, the argument relies on insufficient evidences and groundless assumptions. To make it more convincing, the author should provide more information to support that humans had not hunted mammals.Furthermore, the author has to rule out other possibilities which might also result in the extinction of the mammals.
para 2中写道:“human activities can also have great influence on their extinction indirectly”, 和para 4中的“Moreover, the fire, produced by humans might be another important reason for theextinction in that nearly all the animals are afraid of fire. ” 有重复论证之嫌