Both the passage and lecture discusses about Steller's sea cows, a huge marine mammal, which became extinct in 1768. In the reading passage, several theories are presented about reason of extinction of sea cows. However, the professor in the lecture finds those theories unconvincing and explains the flows of those ideas.
To start with, the passage states that, as a great source of food, sea cows might be over hunted by native people, which causes extinction of that species. But professor opposes this point mentioning that, as sea cows were massive creatures and hunting of one sea cow can provide foods for many people, it is not needed to hunt lots of sea cows. Therefore, it is unlikely to happen to be diminished due to over hunting.
Another theory about extinction, is disturbance of ecosystem that reduced kelp, which is main source of food for sea cows. However, the professor refutes this idea arguing that, if some kind of ecological event occurred, other marine speices should also be effected. But no such effect was reported and therefore it is reasonable to cast doubt on this hypotheses.
Lastly, according to the article, sea cows might be extinct due to hunting of large number of the animals by European fur traders. This theory is also challenged by the professor, who points out that though European traders were the last seen during the extinction of sea cows, it does not make any sense to believe that they are the main cause behind this process. Extinction is a long term process and it started long before arrival of far traders. So, there should be some other reasons of extinction which yet to be found.
Grammar and spelling errors:
Line 5, column 348, Rule ID: THIS_NNS[1]
Message: Did you mean 'these'?
Suggestion: these
...efore it is reasonable to cast doubt on this hypotheses. Lastly, according to the...
^^^^
Transition Words or Phrases used:
also, but, however, if, lastly, so, therefore, kind of, to start with
Attributes: Values AverageValues Percentages(Values/AverageValues)% => Comments
Performance on Part of Speech:
To be verbs : 18.0 10.4613686534 172% => OK
Auxiliary verbs: 5.0 5.04856512141 99% => OK
Conjunction : 8.0 7.30242825607 110% => OK
Relative clauses : 12.0 12.0772626932 99% => OK
Pronoun: 20.0 22.412803532 89% => OK
Preposition: 42.0 30.3222958057 139% => OK
Nominalization: 7.0 5.01324503311 140% => OK
Performance on vocabulary words:
No of characters: 1365.0 1373.03311258 99% => OK
No of words: 280.0 270.72406181 103% => OK
Chars per words: 4.875 5.08290768461 96% => OK
Fourth root words length: 4.09062348924 4.04702891845 101% => OK
Word Length SD: 2.45321269991 2.5805825403 95% => OK
Unique words: 159.0 145.348785872 109% => OK
Unique words percentage: 0.567857142857 0.540411800872 105% => OK
syllable_count: 418.5 419.366225166 100% => OK
avg_syllables_per_word: 1.5 1.55342163355 97% => OK
A sentence (or a clause, phrase) starts by:
Pronoun: 4.0 3.25607064018 123% => OK
Article: 4.0 8.23620309051 49% => OK
Subordination: 3.0 1.25165562914 240% => Less adverbial clause wanted.
Conjunction: 2.0 1.51434878587 132% => OK
Preposition: 3.0 2.5761589404 116% => OK
Performance on sentences:
How many sentences: 13.0 13.0662251656 99% => OK
Sentence length: 21.0 21.2450331126 99% => OK
Sentence length SD: 44.9316377512 49.2860985944 91% => OK
Chars per sentence: 105.0 110.228320801 95% => OK
Words per sentence: 21.5384615385 21.698381199 99% => OK
Discourse Markers: 5.30769230769 7.06452816374 75% => OK
Paragraphs: 4.0 4.09492273731 98% => OK
Language errors: 1.0 4.19205298013 24% => OK
Sentences with positive sentiment : 3.0 4.33554083885 69% => OK
Sentences with negative sentiment : 4.0 4.45695364238 90% => OK
Sentences with neutral sentiment: 6.0 4.27373068433 140% => OK
What are sentences with positive/Negative/neutral sentiment?
Coherence and Cohesion:
Essay topic to essay body coherence: 0.123446493899 0.272083759551 45% => OK
Sentence topic coherence: 0.0457528220619 0.0996497079465 46% => OK
Sentence topic coherence SD: 0.0557657818973 0.0662205650399 84% => OK
Paragraph topic coherence: 0.0771291363244 0.162205337803 48% => OK
Paragraph topic coherence SD: 0.0254303114437 0.0443174109184 57% => OK
Essay readability:
automated_readability_index: 12.3 13.3589403974 92% => Automated_readability_index is low.
flesch_reading_ease: 58.62 53.8541721854 109% => OK
smog_index: 3.1 5.55761589404 56% => Smog_index is low.
flesch_kincaid_grade: 10.3 11.0289183223 93% => OK
coleman_liau_index: 11.02 12.2367328918 90% => OK
dale_chall_readability_score: 8.4 8.42419426049 100% => OK
difficult_words: 66.0 63.6247240618 104% => OK
linsear_write_formula: 9.0 10.7273730684 84% => OK
gunning_fog: 10.4 10.498013245 99% => OK
text_standard: 11.0 11.2008830022 98% => OK
What are above readability scores?
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Rates: 76.6666666667 out of 100
Scores by essay e-grader: 23.0 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.