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.
According to the reading passage, a huge marine mammal as steller' sea cow which lived in the water around Bering Island off the coast of Siberia, have been become extinct in 1768. There have been some theories about their extinction. However, the speaker finds all the ideas dubious and brings up some evidence to refute them all.
First, some naturalists suggest that the overhunting of sea cow, as a source of food, by groups of native Siberian people could be assumed as main reason of their extinction. In contrast, the professor argues that the sea cows were enormous marine animals with 9 meters long and 10 tons weight. While the native Siberian lived in small groups and their population was not large and a couple of sea cow could feed a village for months and they did not need to hunt a lot of them.
Second, the ecological disturbances might cause a negative declination in sea cow's main source of food, kelp; a type of sea plant. Conversely, the speaker asserts that a severe ecological have not been occurred before 1768 and if it happened, other marine animal like whales must have been affected or become extinct. Also, fishing ships have not reported any declination in whale populations.
Finally, some suggested that the sea cows have been become extinct by European fur traders and have been killed by their weapons quickly. On the contrary, the professor dismisses this issue due to the fact that when European traders arrived at the coast of Siberia, the population of sea cows was already quite small and the European traders who were the last to arrive could not be the main reason for their extinction.
| Post date | Users | Rates | Link to Content |
|---|---|---|---|
| 2020-10-30 | yasy.j728@gmail.com | 80 | view |
| 2020-10-21 | serena_wus | 90 | view |
- Now listen to part of a lecture on the topic you just read about Each of the arguments about the benefits of cigarette and other such taxes can be challenged First these taxes don t necessarily lead to healthier behavior For instance high cigarette taxes 80
- Do you agree or disagree with the following statement the opinions of celebrities such as famous celebrities or athletes are more important to young people than they are to older people 78
- Do you agree with the following statement In the past the young people depended too much on their parents to make decisions for them today young people are better able to make decisions about their own lives 73
- Do you agree or disagree with the following sentences movie and television have more negative effects on young people 76
- Professor There should definitely be stricter rules adopted for handling and disposing of coal ash First the regulations we have now for example those that require companies to use liner are not really sufficient Under the current regulations liner has to 85
Transition Words or Phrases used:
also, conversely, finally, first, however, if, second, so, while, in contrast, on the contrary
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 12.0 10.4613686534 115% => OK
Auxiliary verbs: 6.0 5.04856512141 119% => OK
Conjunction : 9.0 7.30242825607 123% => OK
Relative clauses : 8.0 12.0772626932 66% => More relative clauses wanted.
Pronoun: 15.0 22.412803532 67% => OK
Preposition: 34.0 30.3222958057 112% => OK
Nominalization: 8.0 5.01324503311 160% => OK
Performance on vocabulary words:
No of characters: 1358.0 1373.03311258 99% => OK
No of words: 281.0 270.72406181 104% => OK
Chars per words: 4.83274021352 5.08290768461 95% => OK
Fourth root words length: 4.09427095027 4.04702891845 101% => OK
Word Length SD: 2.41271690679 2.5805825403 93% => OK
Unique words: 154.0 145.348785872 106% => OK
Unique words percentage: 0.548042704626 0.540411800872 101% => OK
syllable_count: 419.4 419.366225166 100% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 0.0 3.25607064018 0% => OK
Article: 8.0 8.23620309051 97% => OK
Subordination: 2.0 1.25165562914 160% => OK
Conjunction: 0.0 1.51434878587 0% => OK
Preposition: 4.0 2.5761589404 155% => OK
Performance on sentences:
How many sentences: 11.0 13.0662251656 84% => Need more sentences. Double check the format of sentences, make sure there is a space between two sentences, or have enough periods. And also check the lengths of sentences, maybe they are too long.
Sentence length: 25.0 21.2450331126 118% => OK
Sentence length SD: 60.7440096696 49.2860985944 123% => OK
Chars per sentence: 123.454545455 110.228320801 112% => OK
Words per sentence: 25.5454545455 21.698381199 118% => OK
Discourse Markers: 8.54545454545 7.06452816374 121% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 0.0 4.19205298013 0% => OK
Sentences with positive sentiment : 1.0 4.33554083885 23% => More positive sentences wanted.
Sentences with negative sentiment : 5.0 4.45695364238 112% => OK
Sentences with neutral sentiment: 5.0 4.27373068433 117% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.264010757811 0.272083759551 97% => OK
Sentence topic coherence: 0.104028391925 0.0996497079465 104% => OK
Sentence topic coherence SD: 0.0726754256973 0.0662205650399 110% => OK
Paragraph topic coherence: 0.158669660267 0.162205337803 98% => OK
Paragraph topic coherence SD: 0.0645060391043 0.0443174109184 146% => OK
Essay readability:
automated_readability_index: 14.1 13.3589403974 106% => OK
flesch_reading_ease: 54.56 53.8541721854 101% => OK
smog_index: 8.8 5.55761589404 158% => OK
flesch_kincaid_grade: 11.9 11.0289183223 108% => OK
coleman_liau_index: 11.03 12.2367328918 90% => OK
dale_chall_readability_score: 8.08 8.42419426049 96% => OK
difficult_words: 57.0 63.6247240618 90% => OK
linsear_write_formula: 10.5 10.7273730684 98% => OK
gunning_fog: 12.0 10.498013245 114% => OK
text_standard: 12.0 11.2008830022 107% => OK
What are above readability scores?
---------------------
Rates: 80.0 out of 100
Scores by essay e-grader: 24.0 Out of 30
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Note: the e-grader does NOT examine the meaning of words and ideas. VIP users will receive further evaluations by advanced module of e-grader and human graders.