TPO 34 Integrated Writing: A huge marine mammal known as Steller’s sea cow once lived in the waters around Bering Island off the coast of Siberia. It was described in 1741 by Georg W. Steller, a naturalist who was among the first Europeans to see one.
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October 14, 2020 at 2:36 am
TPO 34 Integrated Writing: A huge marine mammal known as Steller’s sea cow once lived in the waters around Bering Island off the coast of Siberia. It was described in 1741 by Georg W. Steller, a naturalist who was among the first Europeans to see one.
The passage and the lecture focus on the explanations for Steller’s sea cow’s extinctions. The author states three possible theories, while the professor retorts them one by one.
First, according to the writer, the elimination of sea cows is likely caused by overhunting of native people, since Siberian did eat sea cows. However, the speaker points out that sea cows were large in size and heavy in weight, so a couple of sea cows took people months to consume. At the same time, the population of Siberian people was relatively small, so there was not much need for them to overhunt sea cows. Thus, overhunting is unlikely a reasonable explanation.
Second, the author purposes that the decline in kelp population due to ecological changes may lead to the diminishment of sea cows, since sea cows fed on kelp. Nevertheless, the lecturer doubts the possibility that such huge change in ecosystems even existed, because there was no other significant alternations happened to other species in the same period based on current report. Therefore, it is rigid to assume that food shortages result from the decrease in kelp population caused the death of sea cows. So, the second viewport is overturned.
Third, the reading passage suggests that fur traders from European could contribute to the extinction, because they possessed weapons that can kill sea cows in a large scale and in quick speed. But the speaker argues that the massive drop of the number of sea cows occurred way before the fur traders came to the island, approximately hundreds of years earlier . So this made fur traders impossible to be the major reason why sea cows died out. The plausible theory should match the time when sea cows’ population began to shrink. Therefore, the professor rebutted the last point made by the writer.
In summary, all three explanations mentioned by the passage are not logical enough to be a valid theory. According to the lecture, the real cause to sea cow’s death remains unknown.
October 14, 2020 at 2:39 am阅读材料
A huge marine mammal known as Steller’s sea cow once lived in the waters around Bering Island off the coast of Siberia. It was described in 1741 by Georg W. Steller, a naturalist who was among the first Europeans to see one. In 1768 the animal became extinct. The reasons for the extinction are not clear. Here are three theories about the main cause of the extinction.
First, the sea cows may have been overhunted by groups of native Siberian people. If this theory is correct, then the sea cow population would have originally been quite large, but hundreds of years off too much hunting by the native people diminished the number of sea cows. Sea cows were a good source of food in a harsh environment, so overhunting by native people could have been the main cause of extinction.
Second, the sea cow population may have become extinct because of ecosystems disturbances that caused a decline in their main source of food, kelp (a type of sea plant). Kelp populations respond negatively to a number of ecological changes. It is possible that ecological changes near Bering Island some time before 1768 caused a decrease of the kelp that the sea cows depend on.
Third, the main cause of extinction of the sea cows could have been European fur traders who came to the island after 1741. It is recorded that the fur traders caught the last sea cow in 1768. It thus seems reasonable to believe that hunting by European fur traders, who possessed weapons that allowed them to quickly kill a large number of the animals, was the main cause of the sea cow’s extinction.
听力材料
The truth is we don’t know what the main cause of extinction of Steller’s sea cow was. There are problems with each of the theories that you read about.First, the sea cows were massive creatures. They were up to nine meters long and could weigh over ten tons, just enormous. A couple of sea cows could feed a small Siberian village for months. And the population of the native Siberian people wasn’t very large. So while the Siberians certainly did hunt the sea cows, they didn’t need to hunt a lot of them. So it’s unlikely they were the ones who brought the sea cows to the point of extinction.Second, about a hypothetical decrease in kelp caused by ecological disturbances, well, if something severe really happened in the ecosystem near Bering Island sometime before 1768, it would have affected not just the kelp but also other parts of the ecosystem. For example, it would have caused the decline in other marine animals like whales. But fishing ships in the area did not report a whale decline. Since there is no indication of broader ecosystem problems, the kelp was probably growing just fine and the sea cows did not experience food shortage.Third, it might seem like the European traders were responsible because the sea cows became extinct soon after the Europeans arrived. But, actually, by the time that the Europeans arrived, the sea cow population was already quite small. We have evidence that the sea cow population was at its largest hundreds of years before the 1700s. So something was causing a serious and on-going decrease in the sea cow population long before the Europeans arrived in the Bering Island area. Whatever this something was, it should be considered the main cause of the extinction, not the European traders who were just the last to arrive.
October 15, 2020 at 9:16 pmScore: ungraded
Issues:
- About 50% of the sentences exceed 20 words. Shorten/split them.
- About 25% of the sentences are passive. Convert some of them into their active counterparts.
I will send you screenshots to illustrate specific problems/errors.
