[Smart Economics] Why Did the Dinosaurs Go Extinct?

Is the Extinction of Species Really a Disaster for Earth’s Environment?

Whenever dinosaur fossils that lay buried underground for ages are discovered, humanity is quietly stirred with inspiration. It is because the idea that animals several times larger than humans once lived on this planet feels like a story from a completely different world. Children’s fascination with dinosaur cartoons and movies likely stems from the same sense of mystery dinosaurs evoke. Why the dinosaurs, which dominated Earth during the Mesozoic era, disappeared remains one of humanity’s longstanding mysteries. For a long time, scientists have tried to solve it. That effort may stem from the pure curiosity of a child, or from the desire to learn a cautionary lesson that might help humanity avoid a similar catastrophe.

According to research to date, the dinosaurs are believed to have gone extinct because of abrupt climate change around 65 million years ago, when the Mesozoic gave way to the Cenozoic. Scholars differ on what caused that climate change. At present, the most persuasive theory is that a giant meteorite struck Mexico’s Yucatán Peninsula, and the impact altered Earth’s climate. Some scholars also argue that volcanic activity on India’s Deccan Plateau brought about the climatic shift.

Because the extinction of the dinosaurs happened so long ago, even modern science cannot fully explain it. And since the extinction itself likely did not occur in a single instant but progressed gradually over thousands or tens of thousands of years, more research is needed to determine the exact cause.

It Is Estimated That Five Mass Extinctions Have Occurred on Earth

For the general public, the most famous case of species extinction is the “Cretaceous mass extinction” in which the dinosaurs died out. But the Cretaceous event was not the only extinction event in Earth’s history. Since life first appeared on Earth, there have been five major mass extinctions identified by scientists: three in the Paleozoic and two in the Mesozoic.

First, there were three mass extinctions in the Paleozoic. During the “1st mass extinction (Ordovician),” 50% of all species disappeared, and in the “2nd mass extinction (Devonian),” 70% vanished. For the organisms living at the time, these must have been catastrophes of enormous scale. To make matters worse, the “3rd mass extinction (Permian)” wiped out 96% of marine species and 70% of land species. An extinction rate of 96% meant the oceans were, in effect, almost emptied of life. Because of its severity, scientists have separately dubbed this 3rd mass extinction “the mother of all extinctions.” Yet even under such devastating conditions, life did not disappear from Earth, and ecosystems continued on.

There were two mass extinctions in the Mesozoic. In the “4th mass extinction (Triassic),” most of the giant reptiles that had dominated the land disappeared, with the exception of dinosaurs. The “5th mass extinction (Cretaceous)” was the very “Cretaceous mass extinction” in which the dinosaurs died out. In the Cenozoic, the era in which humanity lives, there has not yet been a mass extinction on the same scale as those of the past.

The reason for discussing past mass extinctions at length is that, while extinction is shocking, it is also part of the order of nature. The emergence and extinction of a species are as natural as the birth and death of an individual organism. Therefore, it is excessive to automatically conclude that the disappearance of any species is necessarily environmental destruction.

Species Extinction Has Always Been a Natural Phenomenon

Scholars differ on whether the currently observed decline in species is significant enough to be called Earth’s sixth mass extinction. Some impatient people flatly assert that a “6th mass extinction” is now underway, but we cannot even confirm whether the number of species is increasing or decreasing. Even today, newly discovered species are still being identified and reported by the scientific community. Biology still estimates that many species on Earth remain unnoticed by human eyes. Given that humans do not yet have a complete grasp of the status of all species across the planet, it is unscientific to insist with certainty that species are declining.

Even if, for the sake of argument, we concede that the overall number of species has somewhat decreased, would that really be something highly unnatural and deeply alarming for humanity? No. Whether extinction is caused by environmental change brought about by humans or by natural forces such as meteorites or volcanic eruptions, nature gives rise to new species adapted to changed conditions.

The 3rd Permian extinction, which marked the end of the Paleozoic, erased the overwhelming majority of Earth’s species, yet in the Mesozoic that followed, ecosystems were once again filled with new species. Because the 4th Triassic extinction eliminated most reptiles, dinosaurs were able to become the dominant species on Earth without much competition. Had the 5th Cretaceous extinction not occurred, the age of dinosaurs might have lasted longer, and humanity might never have come to dominate the Earth.

Sometimes newspapers report that changes in sea temperature around the Korean Peninsula have altered fishery patterns. Some people point to this and fearfully claim it is evidence of environmental destruction. But if fishing grounds that once yielded pollock and sailfin sandfish now yield squid or anchovies, can we really say the marine ecosystem has been destroyed?

The circulation of species is similar to runners passing a baton in a relay race. When the organisms that previously existed disappear, new ones fill the empty space. And when those in turn disappear, still newer organisms inherit that vacant place. Species do not simply go extinct; rather, the distribution of species changes as habitats change. A more neutral expression would be not environmental destruction but environmental change, and not so much species extinction as species change. In the short term, species may appear to be going extinct, but in the long term they are always changing.

△ Please Remember

Since life first appeared on Earth, scientists estimate that there have been five major mass extinctions of species: three in the Paleozoic and two in the Mesozoic. The circulation of species means that when formerly existing organisms disappear, new ones take their place. A more neutral expression would be not environmental destruction but environmental change, and not so much species extinction as species change.

Sung-no Choi, President of the Center for Free Enterprise (CFE)

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Original title: [스마트 경제 읽기] 공룡은 왜 멸종했을까

Author: Sung-no Choi

Date: 2021-02-22

Source: https://www.cfe.org/bbs/bbsDetail.php?cid=column&pn=5&idx=23518