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TOEFL reading: megafauna extinction


Hi, let's tackle a set of TOEFL reading questions together.

I'll guide you through applying the problem-solving strategies I teach in my TOEFL reading course or TOEFL reading book. Please review the online course or ebook to gain the necessary foundation to answer these questions quickly and accurately.

Today's passage: "Overkill of the North American Megafauna." This passage is significant as it resembles the structure of many TOEFL passages that  focus on evaluating a scientific hypothesis.


Let’s skim the passage. 

Para 1

TOEFL reading

OK, the rest looks like minor details: as soon as you see numbers or examples (e.g., sentences beginning with “for example,”) you can skip them as they are minor details.  So what we learned are these:

  • large mammals disappeared in North America thousands years ago  

  • Why or how did that happen?

  • one explanation =  the Pleistocene overkill" hypothesis (they were killed by Clovis people during the Pleistocene era)

  • the hypothesis = controversial 

Moving on paragraph 2, it presents an interesting point. The climate changed during the Pleistocene period, but this climate change happened before too. The only difference between this Pleistocene period and previous times is  the presence of human hunters of these large mammals. So is it an accident or a causation?

Para 3

Of course we don’t know. That's why we need evidence! Martin defends the pleistocene hypothesis with a model that connects the mammal extinction with the human killing. made a computer model that supports the hypothesis. 

Para 4

is a more  minor detail as you can see there are a lot of numbers. So skip it.

Para 5

“Many scholars continue to support this scenario. For example,...” so we know that the rest is going to be a minor detail. This paragraph introduces another person who supports the pleistocene overkill  hypothesis.

Para 6

Now it gets interesting since it talks about problems with the model. so we know that this para is going to be an argument against the Plscieton overkill hypothesis. So what's the problem?  

  • problem = very little archaeological evidence to support it. 

  • Martin admits this problem. But what is his response to the problem? 

  • Martin’s reaction to the problem = the lack of  archaeological evidence actually supports his model. HOW?

  • There is no evidence because it happened so quickly.


The author’s reaction to Martin’s reaction = weak, not convincing.

Grayson = if humans killed the mammals, there has to be strong evidence, 

  • example = extinction of moa of New Zealand (humans killed moas and there is strong archeological evidence)

  • Many megafauna disappeared even before the Clovis people showed up.


  • The passage presents the Pleistocene overkill hypothesis as an explanation for the extinction of North American megafauna.

  • The hypothesis is supported by Martin's computer model but faces challenges from Grayson due to the lack of strong archaeological evidence.


Q1 vocab strategy: inferring from known words

The word "distinctive" in the passage is closest in meaning to

  • A.hidden

  • B.characteristic

  • C.scattered

  • D.rare

“distinctive.” Think of a word that you know, “distinguish.” It means you can recognize the difference among things. How is it possible? Because a thing has its own characteristics. So we can infer this:


distinctive = distinguishing, characteristic, typical, unique

Q2. Inference question strategy: disjunctive syllogism

Although the climate changed at the end of the Pleistocene, warming trends had happened before. A period of massive extinction of large mammals like that seen about 11,000 years ago had not occurred during the previous 400,000 years, despite these changes. The only apparently significant difference in the Americas 11,000 years ago was the presence of human hunters of these large mammals. Was this coincidence or cause-and-effect?

According to paragraph 2, what suggests that human activity played a role in the extinction of mammals about 11,000 years ago?

  1. Climate changes that would have favored human population expansion occurred at the time of the extinctions.

  2. The presence of human hunters had caused animal extinctions in other time periods.

  3. There was a pattern of climate change earlier than 11,000 years ago that had not caused animal extinctions.

  4. Harmful climate changes 11,000 years ago would have required humans to hunt larger numbers of animals for food.

This type of question has been asked several times in the TOEFL. I explained how to solve this type in my book and course. Basically, you need to know disjunctive syllogism, also called disjunction elimination, which looks like this: 

  1. X or Y. 

  2. Not Y. 

  3. Therefore X. 

Now substitute X and Y as follows: 

  1. Climate change was the reason for the megafauna extinction OR human overkill was the reason for the megafauna extinction.

  2. Climate changes had happened before but megafauna did not become extinct.

  3. Therefore, human overkill must have been the reason for the megafauna extinction

To conclude 3, we need to show that 2 is the case. Which one describes 2? C does.


Q3. Paraphrase question strategy: essential info

With researcher J. E. Mosimann, he has co-authored a work in which a computer model showed that in around 300 years, given the right conditions, a small influx of hunters into eastern Beringia 12,000 years ago could have spread across North America in a wave and wiped out game animals to feed their burgeoning population.

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information

  1. A computer model was designed to determine how long it would have taken for a small group of hunters to spread across North America.

  2. A computer model showed that it was possible for a small group of hunters to spread across North America and kill off game animals in just 300 years.

  3. According to a computer model, people coming into North America 12,000 years ago had to kill game animals in order to feed their population.

  4. According to a computer model, about 12,000 years ago conditions enabled a small group of hunters to enter and cross North America in about 300 years.

To paraphrase, first, find the main clause, which is ”he has co-authored a work.” This doesn’t have that much info. So we should see what that work was. The work is a computer model that shows that a small group of arriving hunters to the land could have spread and killed all the game animals to feed their growing society

A omits essential info, killing

B has all the things essential

C “had to kill” is not right. The highlighted sentence doesn’t say it was necessary.

D is way off.

Q4. Information question strategy: qualifying words

The researchers ran the model several ways, always beginning with a population of 100 humans in Edmonton, in Alberta, Canada, at 11,500 years ago.Assuming different initial North American big-game-animal populations (75-150 million animals) and different population growth rates for the human settlers (0.65%-3.5%), and varying kill rates, Mosimann and Martin derived figures of between 279 and 1,157 years from initial contact to big-game extinction.

Which of the following best describes the results of the research discussed in paragraph 4?

  1. A.Scientists used mathematical models to show that most of the extinctions occurred in areas where humans had recently arrived.

  2. Scientists established that the main population of North Americans who hunted lived in Canada during the time of the megafauna extinctions.

  3. Scientists used numerical models to confirm that a small population of humans could have caused big-game extinctions in a relatively short period of time.

  4. Scientists used statistics to prove beyond doubt the currently accepted view that human hunters were the main cause of the megafauna extinctions.

Martin ran the model several ways, meaning that he changed the parameters, yet the result was basically the same. It takes between 300 to 1000 years to kill all the megafaunas. 

A not mentioned

B The location in Canada is used as an assumption. they did not establish it.

C. Confirm, could have,  relatively short. These are all qualifying words, it’s a form of careful writing, the hallmark of academic writing. I emphasize this aspect in my book and course. Please study them from them. 

D. “Prove” is not an appropriate word to talk about empirical science. again study my book or course. So D is false.

Because of the way the options are worded, C has to be the answer.

Q5 Information question strategy: qualifying words

Many scholars continue to support this scenario.For example, geologist Larry Agenbroad has mapped the locations of dated Clovis sites alongside the distribution of dated sites where the remains of wooly mammoths have been found in both archaeological and purely paleontological contexts.These distributions show remarkable synchronicity (occurrence at the same time).

Which of the following statements about Larry Agenbroad's work is implied in the discussion in paragraph 5?

  1. Agenbroad showed that Mosimann and Martin's estimates of the amount of time needed to drive big-game to extinction were correct.

  2. Agenbroad's maps were the first to indicate the ages of the Clovis sites.

  3. Agenbroad reinforced the idea that humans could have caused the extinctions.

  4. Agenbroad's studies of wooly mammoths led to his discovery of Clovis sites.

The para begins with “Many scholars continue to support this scenario” and Agenbroad is an example of the supporters. What did Agenbroad do? He mapped the Clovis sites and the mammoth sites and found that the two occurred at the same time. This fact confirms the overkill hypothesis.   

  1. no

  2. no. also, “the first” is a suspicious word as it is too strong. 

  3. reinforce = support or confirm; “could have” is carefully written, so well qualifed. So. C is a good choice.

  4. no

TOEFL reading: understand the question 

Q6. Information question strategy: hidden information

There are, however, many problems with this model.Significantly, though a few sites are quite impressive, there really is very little archaeological evidence to support it.Writing in 1982, Martin himself admitted the paucity of evidence;for example, at that point, the remains of only 38 individual mammoths had been found at Clovis sites. In the years since, few additional mammoths have been added to the list;there are still fewer than 20 Clovis sites where the remains of one or more mammoths have been recovered, a minuscule proportion of the millions that necessarily would have had to have been slaughtered within the overkill scenario.

According to paragraph 6, which of the following statements challenges the view that hunting by humans caused the extinctions of North American megafauna?

  1. The Clovis sites that contain the remains of mammoths were settled by humans long after the extinctions occurred.

  2. Only a few of the Clovis sites are located near known mammoth habitats.

  3. No archaeological evidence of extinctions has been found at Clovis sites since 1982.

  4. The number of mammoth remains found at Clovis sites is smaller than would be expected if hunting by humans had caused the extinctions.

challenge = oppose, doubt, discredit, distrust, misbelieve

champion = endorse, support, embrace, advance, espouse

Paragraph 6 talks about a problem with the overkill hypothesis: lack of evidence. Grayson argues that if humans are the cause of the extinction, there has to be sufficient evidence.

A is incorrect. Agenbroad confirmed synchronicity.

B: almost! The problem with B is “known mammoth habitats.”  We don’t know their habitats. We only know the sites of their remains (graveyards). B is a trap.

C: “In the years since, few additional mammoths have been added to the list” So C is false.

D is what we are looking for, that is, not enough archaeological evidence. Correct answer.  

Q7. Rhetorical purpose question strategy: counterexample

Though Martin claims the lack of evidence actually supports his model—the evidence is sparse because the spread of humans and the extinction of animals occurred so quickly—this argument seems weak. And how could we ever disprove it?As archaeologist Donald Grayson points out, in other cases where extinction resulted from the quick spread of human hunters—for example, the extinction of the moa, the large flightless bird of New Zealand—archaeological evidence in the form of remains is abundant. Grayson has also shown that the evidence is not so clear that all or even most of the large herbivores in late Pleistocene America became extinct after the appearance of Clovis. Of the 35 extinct genera, only 8 can be confidently assigned an extinction date of between 12,000 and 10,000 years ago.Many of the older genera, Grayson argues, may have succumbed before 12,000 B.C., at least half a century before the Clovis showed up in the American West.

In paragraph 7, why does the author mention that there is abundant archaeological evidence for the extinction of the New Zealand moa?

  1. To show that extinctions occurred in areas other than North America.

  2. To challenge Martin's claim that the lack of megafauna remains supports his model of the megafauna extinctions.

  3. To identify a country where humans were highly skilled as hunters.

  4. To help explain why it is unclear whether all large herbivores of late Pleistocene America became extinct after the appearance of Clovis.

The moa case of New Zealand is a counterexample to Martin’s overkill hypothesis. So it is used to challenge Martin’s claim that no evidence is evidence. Learning counterexamples is very important for TOEFL reading, and learning how to  use them to answer questions from my book or course. answer: B

Q8. Inference question  strategy: meaning of subjunctive past perfect

Paragraph 7 suggests that Donald Grayson believes which of the following about the remains at Clovis sites and megafaunal extinctions?

  1. The rapid rate of the spread of humans explains why the extinctions also occurred at a rapid rate.

  2. The lack of evidence of human-caused extinctions is not surprising in view of the speed with which the extinctions occurred.

  3. It is likely that more evidence will be found as dating methods improve.

  4. If humans did contribute to the extinction, much more evidence of that would have been found by now.

Grayson rejects Martin’s overkill hypothesis for the reason that there’s not enough evidence. So you should look for an option that talks about that.

A no

B supports Martin’s view. So no

C supports Martin’s view. 

D is written in the subjunctive past perfect form, which indicates the opposite of past events. So what D really means is that since humans were not the cause of the extinction, there hasn’t been much evidence. So D is correct.

Q9. Sentence insertion question strategy: moving ideas from old to new

Look at the four squares [■] to add the sentence to the passage.

One possible nonhuman cause—weather cycles—is not consistent with what scientists know about the timing of the extinctions..

  1. ■ Although the climate changed at the end of the Pleistocene, warming trends had happened before.

  2. ■ A period of massive extinction of large mammals like that seen about 11,000 years ago had not occurred during the previous 400,000 years, despite these changes. 

  3. ■ The only apparently significant difference in the Americas 11,000 years ago was the presence of human hunters of these large mammals. 

  4. ■ Was this coincidence or cause-and-effect?

The target sentence introduces a non-human cause, weather cycles ( = climate changes). A talks about climate change, and the target sentence introduces climate change, so the target sentence should come before A. This way of moving ideas is called transitioning from new to old. That is, first introduce a topic and then give a detail.

Q10. Summary question strategy: qualifying words as clues

Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it. To review the passage, click VIEW TEXT About 11,000 years ago, all of North America's megafauna became extinct.

  1. That the first humans migrated to North America near the same time as the extinctions of the megafauna has led many to believe that hunting by humans was a significant cause of those extinctions.

  2. Support for the hypothesis that hunting by humans caused the extinctions has been provided by computer models, as well as by the discovery of some mammoths' remains near human settlements.

  3. There is more evidence that human settlers hunted large flightless birds like the moa into extinction than there is that hunters caused the extinction of large mammals like the mammoth.

  4. Early North Americans known as the Clovis society developed spears in order to hunt enough large animals to feed their population as it expanded across vast areas of the continent.

  5. Scientists have proven that the human hunters of large animals who migrated across North America grew in number so quickly that they killed off most of the megafauna within a few hundred years.

  6. Some scholars argue that the evidence linking mammoth remains to human settlements is insufficient to establish that hunting by humans was a significant factor in the megafauna extinctions.

Introductory summary sentence: About 11,000 years ago, all of North America's megafauna became extinct.

So we can expect that the choices will talk about theories relating to this phenomenon.

A is the pleistocene overkill hypothesis. So we keep iit.

B is about Martin’s model and some evidence for the hypothesis, so keep B

C is true, but minor details. to see whether it is an essential detail or minor details, check whether it supports the ISS. C  does not support the ISS. so C is a minor detail.

D: ``hunt enough large animals'' is wrong. if they killed only enough animals to feed their population, the large mammal might not have gone extinct. So D is false.

E is wrong because of “proof.”  Study my book or course. you can immediately get rid of wrong ones by just looking at the words used.

F talks about the problem with the overkill hypothesis, so F should be included in the summary.

Answer: ABF