The Sixth Extinction

The Sixth Extinction Chapter 3 Summary & Analysis

Summary
Analysis
In 1832, William Whewell, president of the Geological Society of London, coined an important word: “catastrophist.” While this word has taken on some new meanings since 1832, Whewell didn’t mean it as an insult: a catastrophist, as he understood it, was a scientist who believed that the history of the planet was characterized by sudden, global catastrophes that caused large numbers of species to go extinct. The opposite of catastrophism is uniformitarianism, which is closer to Darwin’s idea of species and landscape gradually changing in tandem.
As scientists became aware of extinction, they developed many theories about what caused extinction. These theories can be divided into two main camps: uniformitarianism and catastrophism. Contemporary scientists argue for a mixture of the two theories—in essence, that extinction is generally a uniform process until an era of mass-extinction, when it becomes catastrophist.
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One early “uniformitarian,” an associate of Whewell’s, was the geologist Charles Lyell. Lyell was an Oxford-educated scientist who’d been friendly with Cuvier. Lyell studied the rocks of Paris, Italy, and England, and found no evidence that there had been a global catastrophe that caused species to go extinct—all the evidence pointed to a slow, gradual process of erosion in the planet’s geological structure. Lyell proposed that, while some species certainly went extinct, extinction was a slow, gradual process, not a sudden, catastrophic mass-death. Lyell was a popular lecturer and author who toured the U.S. popularizing his ideas about geology.
Like Cuvier, Lyell was a great scientist. He was also a talented publicist who took pains to popularize his theories with the general public in the United States. Lyell’s ideas about the slow, gradual nature of geological and biological change proved to be very influential—indeed, scientists have only begun to take a more catastrophist view of planetary history in the last few decades.
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One of Lyell’s most important readers was Charles Darwin, who was in his early twenties at the same time that Lyell was a major figure in the scientific community. Darwin sailed onboard the HMS Beagle, where he worked as a scientific researcher in the Galápagos Islands, among other places. After returning from his long voyage, Darwin began to develop his famous theory of evolution to explain the existence of some of the strange animals he’d encountered. Throughout this influential and historic voyage, Darwin was a prodigious reader of Charles Lyell’s writings.
Lyell’s notion that the history of the Earth is a history of slow, steady, and gradual change proved very influential for a young Charles Darwin. This adds complexity to Kuhn’s theory of paradigm shifts. The relationship between Lyell and Darwin was one of direct influence more than it was a dramatic rupture in worldview. Indeed, scientific progress often happens at a more incremental level than the paradigm shift—it’s often the accumulation of minor discrepancies, rather than a watershed discovery, that fractures a paradigm.
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Although Lyell was an important advocate for the principle of gradualism in geology—he believed that the geological world was changing in small, almost immeasurable ways—he didn’t believe in any theory of evolution. Darwin disagreed with Lyell, and proceeded to apply Lyell’s principles of gradual change to life, not just geology. Darwin argued that there could be no extinction without the origin of new species. Life forms on Earth, he argued, were constantly in competition for the limited resources of food, water, and shelter. Species went extinct because other species had qualities that made them superior at finding food and shelter and, ultimately, reproducing. By the same logic, new species must appear over time, either surviving because of their superior qualities or dying out. Darwin argued that the origin of species was an incredibly drawn-out process, lasting many thousands of years. No human being had ever witnessed the origin of a new species, because it took so long—thus explaining why Cuvier’s examination of fossilized cats didn’t necessarily disprove evolution.
Darwin completed Cuvier’s theory of extinction by arguing that, if some animals went extinct over time, then other animals must appear over time. Darwin’s theory of natural selection was revolutionary because it was based on the premise that there are too many species competing for too few resources. Where many of Darwin’s contemporaries conceived of the natural world as a peaceful, tranquil place, Darwin saw nature as a battleground—different species were racing against the clock to reproduce and avoid extinction. Darwin’s gradual model of natural selection explains why Cuvier’s objections to the theory of evolution were invalid—natural selection takes many tens of thousands of years, which explains why modern cats and ancient cats look the same.
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Kolbert visits the Icelandic Museum of Natural History to learn about the great auk, an extinct bird that probably died out in the mid-19th century. At the Museum, she sees fossils belonging to the great auk, or Pinginius impennis. The great auk was a large bird, almost three feet tall, that resembled a penguin—it had tiny wings, and couldn’t fly. It once lived in places as different as Norway, Italy, and Florida (the region now known as Newfoundland was once full of great auks, too). Great auks were excellent swimmers, and spent most of their life in the water. However, human beings hunted great auks into extinction. In America, for example, Native American tribesmen and, later, European fisherman, used auks for food and fuel.
Charles Darwin believed that no human being had ever witnessed the emergence of a new species, but this chapter demonstrates that humans have, at the very least, witnessed the extinction of an old species without even realizing it. The story of the auk, in a sense, supports Darwin’s notion of nature as a battlefield for resources, though Darwin did not devote much time to the idea that one species might exploit another species out of existence.
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The final home of great auks was probably the Icelandic island of Eldey. Kolbert traveled there, where she saw huge numbers of gannets—long-necked, cream-colored birds. 150 years ago, fishermen regularly rowed out to the island, where they would encounter great auks. Rumor has it that in 1844, three fishermen rowed to Eldey, where they found the last two great auks on the planet. The fishermen chased the birds around the island, and eventually captured them. In the chase, they broke an auk egg that the two birds had been guarding. Instead of eating the two dead auks, the fishermen sold their catch to an Icelandic dealer, who in turn sold the birds’ remains to a naturalist. Fifteen years later, two naturalists named John Wooley and Alfred Newton went to Iceland to track down the great auk, only to realize that it had gone extinct. Newton spent the rest of his life campaigning for the preservation of sea birds, and eventually succeeded in lobbying for a bill to protect these creatures—one of the first wildlife protection laws in world history.
Alfred Newton is an important figure in the history of science, because he was one of the first scientists to recognize that humans could play an important role in preserving endangered species, such as sea birds. However, Newton probably didn’t understand the extent to which human beings were responsible for mass-extinction—he wanted humans to help preserve endangered wildlife, but didn’t realize that human beings caused wildlife to become endangered in the first place.
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Around the same time that Newton and Wooley were returning from their journey to Iceland, Charles Darwin was publishing a revolutionary paper on the process of natural selection. Darwin’s ideas immediately impressed Newton, and later in life they became friends. Personally, Darwin had encountered the phenomenon of human-caused extinction during his time in the Galápagos Islands. In 1835, Darwin first encountered the Galápagos tortoises, and learned that their population was shrinking at an alarming rate, due to the whalers and fishermen who ate the tortoises. Less than ten years later—by which time Darwin was back in England, Galápagos tortoises had gone extinct. In his most famous book, The Origin of Species, Darwin notes that species become rare before they go extinct, and briefly alludes to human-caused extinction.
Charles Darwin seems to have understood that humans could play a role in the extinction of a species—for instance, he noticed that human beings in the Galápagos Islands were overhunting the native tortoises, causing them to die out quickly. However, Darwin, for all his brilliance, didn’t see the “big picture”—he didn’t realize that human beings were responsible for the extinction of hundreds of different animals.
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Although Darwin was clearly aware of human-caused extinction, he seems not to have found it a serious or troubling phenomenon. Darwin conceived of human beings as, fundamentally, subject to the same laws of natural selection as all other animals. He even recognized that human intelligence was just an evolutionary adaptation, similar to a lion’s claws or a finch’s beak. And yet, Darwin seemed not to understand that humans were unique among animals in one way: they were the only animals who caused other animals to go extinct. Furthermore, the fact that humans could cause other animals to suddenly go extinct suggested that Cuvier was right—cataclysmic events played a major role in extinction.
Darwin conceived of natural selection as a gradual, steady process, rather than a sudden, catastrophic, manmade mass-extinction. Perceptive as he was, he did not anticipate the paradigm shift towards catastrophism. This passage is also important because it introduces the theme of human nature. Implicitly, Darwin took a conservative view of human nature, arguing that humans were, for practical purposes, no different than any other kind of animal. Kolbert, however, argues that humans are fundamentally different from other species—they alter their environments and cause other species to die out.
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