Human Responsibility for Megafaunal Extinctions
Paleontologists are intrigued by the question of what caused a diverse group of large animals (megafauna) to become extinct during the Pleistocene(2.5 million to 11,700 years ago). The discovery of evidence like that found mainly in the American West, where bones of mammoths and other large herbivores have been excavated in undeniable association with the weapons used to kill them, leads some researchers to blame Paleo-Indian hunters for the extinction of North American Pleistocene megafauna. Archaeologist Paul S. Martin, who viewed Clovis sites in modern- day New Mexico as evidence of the first people in North America, argued for decades that overhunting by the newly arrived and rapidly expanding human population caused the swift extermination, around 13,000 years ago, of these animals throughout the New World. He pointed out that over half of the large mammal species found in the Americas when humans first arrived were gone within just a few centuries, especially those whose habits and habitats would have made them most vulnerable to hunters. Martin recognized a comparable extinction event with the peopling of Australia tens of thousands of years earlier, when most of that continent’s native fauna died off. African and Eurasian species were less affected, he argued, due to the long coexistence of humans and their prey and the prey’s conditioning to human hunting behaviors.
Paleo-Indian hunter-gatherers certainly hunted Pleistocene megafauna. As noted earlier, archaeologists have excavated several sites where such game was killed and butchered. But evidence that these animals were human prey doesn’t also prove that humans hunted them to extinction. The problem is complex for reasons that are still hotly contested. First, it has yet to be convincingly demonstrated that Paleo-Indian hunter-gatherers anywhere focused most of their food-getting effort on Pleistocene megafauna. What we’re finding instead is that Paleo-Indian groups hunted and collected a range of animals and plants, the mix of which varied regionally.
Second, species extinction is a natural process, and it’s no less common than the emergence of new species. It happens for various reasons, and at least until modern times, these reasons seldom had anything to do with human agency. Yes, many North American megafaunal species went extinct toward the end of the Pleistocene. But if you look at the North American geological record, you’ll find that many species also became extinct in the Pliocene, Miocene, and so on (many millions of years before humans settled North America). Our point is that the geological record provides abundant evidence that natural processes are sufficient to account for species extinctions in the absence of humans. The presence of Paleo-Indian hunters may also be sufficient, but it hasn’t yet been convincingly demonstrated that these hunters are necessary to explain Pleistocene extinctions.
One possible exception appears to be the extinction of proboscideans-mammoths, mastodons, elephants, and their relatives. Surovell and colleagues took a long-term view of the problem and examined the global archaeological record of human exploitation of proboscideans in 41 sites that span roughly the past 1.8 million years. They conclude that local extinctions of proboscideans on five continents correlate well with the global colonization patterns of humans, not climatic changes or other natural factors. This finding suggests that we can’t entirely dismiss the possibility that humans played an important role in the late Pleistocene extinctions of some species.
The end of the Pleistocene marked an interval of profound climatic and geographical changes (for example, the creation of the Great Lakes)in North America and elsewhere. Geoarchaeologists also recognize that late Pleistocene extinctions and the expansion of Paleo-Indian hunters coincided with a time of widespread drought that was immediately followed by rapidly plunging temperatures. The latter climatic event, called the Younger Dryas, marked a return to near-glacial conditions and persisted for 1,500 years, from roughly 13,000 to 11,500 years ago. And in an extraordinary twist to the story, Firestone and colleagues recently argued that the explosion of a meteor or other large extraterrestrial object over North America about 12,900 years ago contributed directly to the Pleistocene megafaunal extinctions and the onset of the Younger Dryas and, ultimately, to the end of the Paleo-Indian period! While their hypothesis has attracted considerable attention, especially by the educational television networks, the scientific community has expressed considerable skepticism. The degree of human involvement in these New World extinctions will continue to be a controversial issue in American archaeology.
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Paleontologists are intrigued by the question of what caused a diverse group of large animals (megafauna) to become extinct during the Pleistocene(2.5 million to 11,700 years ago). The discovery of evidence like that found mainly in the American West, where bones of mammoths and other large herbivores have been excavated in undeniable association with the weapons used to kill them, leads some researchers to blame Paleo-Indian hunters for the extinction of North American Pleistocene megafauna. Archaeologist Paul S. Martin, who viewed Clovis sites in modern- day New Mexico as evidence of the first people in North America, argued for decades that overhunting by the newly arrived and rapidly expanding human population caused the swift extermination, around 13,000 years ago, of these animals throughout the New World. He pointed out that over half of the large mammal species found in the Americas when humans first arrived were gone within just a few centuries, especially those whose habits and habitats would have made them most vulnerable to hunters. Martin recognized a comparable extinction event with the peopling of Australia tens of thousands of years earlier, when most of that continent’s native fauna died off. African and Eurasian species were less affected, he argued, due to the long coexistence of humans and their prey and the prey’s conditioning to human hunting behaviors.
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.
Sentence Simplification Questions句子简化题
ABones of mammoths and other large herbivores have been excavated alongside human weapons in the American West, where Paleo-Indian peoples hunted these animals to extinction.
BEvidence that Paleo-Indians were highly skilled as hunters comes primarily from the American West, where weapons have been found along with the bones of mammoths.
CThe discovery of weapons together with the remains of animals at sites in the American West has convinced some researchers that the hunting of animals led to their extinction.
DSome researchers believe that the bones of mammoths and other large herbivores excavated in the American West provide evidence that Paleo-Indian hunters had weapons and used them to kill animals.
2
Paleontologists are intrigued by the question of what caused a diverse group of large animals (megafauna) to become extinct during the Pleistocene(2.5 million to 11,700 years ago). The discovery of evidence like that found mainly in the American West, where bones of mammoths and other large herbivores have been excavated in undeniable association with the weapons used to kill them, leads some researchers to blame Paleo-Indian hunters for the extinction of North American Pleistocene megafauna. Archaeologist Paul S. Martin, who viewed Clovis sites in modern- day New Mexico as evidence of the first people in North America, argued for decades that overhunting by the newly arrived and rapidly expanding human population caused the swift extermination, around 13,000 years ago, of these animals throughout the New World. He pointed out that over half of the large mammal species found in the Americas when humans first arrived were gone within just a few centuries, especially those whose habits and habitats would have made them most vulnerable to hunters. Martin recognized a comparable extinction event with the peopling of Australia tens of thousands of years earlier, when most of that continent’s native fauna died off. African and Eurasian species were less affected, he argued, due to the long coexistence of humans and their prey and the prey’s conditioning to human hunting behaviors.
The word “comparable” in the passage is closest in meaning to
Vocabulary Questions词汇题
Arapid
Bprevious
Csimilar
Dsevere
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Paleo-Indian hunter-gatherers certainly hunted Pleistocene megafauna. As noted earlier, archaeologists have excavated several sites where such game was killed and butchered. But evidence that these animals were human prey doesn’t also prove that humans hunted them to extinction. The problem is complex for reasons that are still hotly contested. First, it has yet to be convincingly demonstrated that Paleo-Indian hunter-gatherers anywhere focused most of their food-getting effort on Pleistocene megafauna. What we’re finding instead is that Paleo-Indian groups hunted and collected a range of animals and plants, the mix of which varied regionally.
According to paragraph 2, what is one problem with the argument that humans caused the megafaunal extinctions?
Factual Information Questions事实信息题
APaleo-Indians may have eaten animals that died by natural means, rather than as prey hunted by humans.
BMegafauna may have made up only a portion of the diverse diet of Paleo-Indians.
CIt is unclear whether Paleo-Indians deliberately hunted megafauna, or only killed them occasionally in self-defense.
DHumans were not even present in many of the regions where megafauna went extinct.
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Second, species extinction is a natural process, and it’s no less common than the emergence of new species. It happens for various reasons, and at least until modern times, these reasons seldom had anything to do with human agency. Yes, many North American megafaunal species went extinct toward the end of the Pleistocene. But if you look at the North American geological record, you’ll find that many species also became extinct in the Pliocene, Miocene, and so on (many millions of years before humans settled North America). Our point is that the geological record provides abundant evidence that natural processes are sufficient to account for species extinctions in the absence of humans. The presence of Paleo-Indian hunters may also be sufficient, but it hasn’t yet been convincingly demonstrated that these hunters are necessary to explain Pleistocene extinctions.
Why does the author provide the information that in North America “many species also became extinct in the Pliocene, Miocene, and so on (many millions of years before humans settled North America)”?
Rhetorical Purpose Questions修辞目的题
ATo emphasize that species extinctions do not always have a human cause
BTo provide evidence that Paleo-Indian hunters were present in North America earlier than previously thought
CTo argue that the megafauna may have become extinct because of the loss of other species that they depended on for food
DTo support the claim that the largest megafauna extinctions did not actually take place during the Pleistocene
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Second, species extinction is a natural process, and it’s no less common than the emergence of new species. It happens for various reasons, and at least until modern times, these reasons seldom had anything to do with human agency. Yes, many North American megafaunal species went extinct toward the end of the Pleistocene. But if you look at the North American geological record, you’ll find that many species also became extinct in the Pliocene, Miocene, and so on (many millions of years before humans settled North America). Our point is that the geological record provides abundant evidence that natural processes are sufficient to account for species extinctions in the absence of humans. The presence of Paleo-Indian hunters may also be sufficient, but it hasn’t yet been convincingly demonstrated that these hunters are necessary to explain Pleistocene extinctions.
One possible exception appears to be the extinction of proboscideans-mammoths, mastodons, elephants, and their relatives. Surovell and colleagues took a long-term view of the problem and examined the global archaeological record of human exploitation of proboscideans in 41 sites that span roughly the past 1.8 million years. They conclude that local extinctions of proboscideans on five continents correlate well with the global colonization patterns of humans, not climatic changes or other natural factors. This finding suggests that we can’t entirely dismiss the possibility that humans played an important role in the late Pleistocene extinctions of some species.
Which of the following statements about the extinction of proboscideans is supported by the discussion in paragraphs 3 and 4?
Factual Information Questions事实信息题
AThe global archaeological record provides no evidence of proboscidean extinction during the Pleistocene, but it does provide evidence from other periods.
BThe most likely explanation for the extinction of proboscideans is that it resulted from changes in climate and other natural events.
CCorrelating proboscidean extinctions with patterns of human colonization is almost impossible.
DThe cause of proboscidean extinction may be different from that of other megafaunal extinctions.
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One possible exception appears to be the extinction of proboscideans-mammoths, mastodons, elephants, and their relatives. Surovell and colleagues took a long-term view of the problem and examined the global archaeological record of human exploitation of proboscideans in 41 sites that span roughly the past 1.8 million years. They conclude that local extinctions of proboscideans on five continents correlate well with the global colonization patterns of humans, not climatic changes or other natural factors. This finding suggests that we can’t entirely dismiss the possibility that humans played an important role in the late Pleistocene extinctions of some species.
According to paragraph 4, what did Surovell and colleagues conclude about humans and proboscideans?
Factual Information Questions事实信息题
AHumans certainly hunted proboscideans, but were probably not responsible for their extinction.
BHumans may have been responsible for some localized extinctions but not global ones.
CHumans could only have had a small role in proboscidean extinctions because humans had not yet colonized all five continents at the time of the extinctions.
DHuman hunting is a more likely explanation for the extinction of proboscideans than climate change or other natural causes.
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The end of the Pleistocene marked an interval of profound climatic and geographical changes (for example, the creation of the Great Lakes)in North America and elsewhere. Geoarchaeologists also recognize that late Pleistocene extinctions and the expansion of Paleo-Indian hunters coincided with a time of widespread drought that was immediately followed by rapidly plunging temperatures. The latter climatic event, called the Younger Dryas, marked a return to near-glacial conditions and persisted for 1,500 years, from roughly 13,000 to 11,500 years ago. And in an extraordinary twist to the story, Firestone and colleagues recently argued that the explosion of a meteor or other large extraterrestrial object over North America about 12,900 years ago contributed directly to the Pleistocene megafaunal extinctions and the onset of the Younger Dryas and, ultimately, to the end of the Paleo-Indian period! While their hypothesis has attracted considerable attention, especially by the educational television networks, the scientific community has expressed considerable skepticism. The degree of human involvement in these New World extinctions will continue to be a controversial issue in American archaeology.
The word “onset”in the passage is closest in meaning to
Vocabulary Questions词汇题
Aextent
Bbeginning
Cimpact
Doutcome
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The end of the Pleistocene marked an interval of profound climatic and geographical changes (for example, the creation of the Great Lakes)in North America and elsewhere. Geoarchaeologists also recognize that late Pleistocene extinctions and the expansion of Paleo-Indian hunters coincided with a time of widespread drought that was immediately followed by rapidly plunging temperatures. The latter climatic event, called the Younger Dryas, marked a return to near-glacial conditions and persisted for 1,500 years, from roughly 13,000 to 11,500 years ago. And in an extraordinary twist to the story, Firestone and colleagues recently argued that the explosion of a meteor or other large extraterrestrial object over North America about 12,900 years ago contributed directly to the Pleistocene megafaunal extinctions and the onset of the Younger Dryas and, ultimately, to the end of the Paleo-Indian period! While their hypothesis has attracted considerable attention, especially by the educational television networks, the scientific community has expressed considerable skepticism. The degree of human involvement in these New World extinctions will continue to be a controversial issue in American archaeology.
According to paragraph 5, how was the hypothesis of Firestone and his colleagues received?
Factual Information Questions事实信息题
AIts science was misunderstood because of the way it was described on educational television.
BIt has become the leading hypothesis about the extinctions of megafauna.
CThe scientific community largely ignored it.
DMany scientists doubt that it is true.
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Paleontologists are intrigued by the question of what caused a diverse group of large animals (megafauna) to become extinct during the Pleistocene(2.5 million to 11,700 years ago). The discovery of evidence like that found mainly in the American West, where bones of mammoths and other large herbivores have been excavated in undeniable association with the weapons used to kill them, leads some researchers to blame Paleo-Indian hunters for the extinction of North American Pleistocene megafauna. Archaeologist Paul S. Martin, who viewed Clovis sites in modern- day New Mexico as evidence of the first people in North America, argued for decades that overhunting by the newly arrived and rapidly expanding human population caused the swift extermination, around 13,000 years ago, of these animals throughout the New World. ⬛He pointed out that over half of the large mammal species found in the Americas when humans first arrived were gone within just a few centuries, especially those whose habits and habitats would have made them most vulnerable to hunters. ⬛Martin recognized a comparable extinction event with the peopling of Australia tens of thousands of years earlier, when most of that continent’s native fauna died off. ⬛African and Eurasian species were less affected, he argued, due to the long coexistence of humans and their prey and the prey’s conditioning to human hunting behaviors.⬛
Look at the four squaresthat indicate where the following sentence could be added to the passage
On the other hand, animals in certain parts of the world survived human hunting, yet this fact did not pose a serious challenge to Martin’s theory.Insert Text Questions句子插入题
Where would the sentence best fit？Click on a square sentence to the passage.
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Archaeologists disagree about the role of human hunting in the extinction of North American megafauna at the end of the Pleistocene.
Prose Summary Questions概要小结题
Select 3 answers
APaleo-Indian hunters arrived on the continent shortly before many megafauna went extinct, and there is some evidence to connect human expansion with the extinction of proboscideans.
BPart of the controversy stems from differing interpretations of the archaeological evidence, particularly whether or not certain animal wounds were inflicted by human weapons.
COverall, the scientific community today agrees with Martin’s hypothesis, though television and popular culture have tended to favor the meteor explanation.
DHumans consumed many kinds of plants and animals, so their food gathering may not have been sufficiently directed at megafauna to cause their extinction.
ESome argue that if the extinctions were caused by climate change, they would also have occurred in Africa Eurasia, and Australia, where climate changes were even more extreme.
FMany of the megafuana extinctions could easily have happened for purely natural reasons-a dry, cold period, or perhaps even a meteor.
