The Sixth Extinction

The Sixth Extinction Chapter 12 Summary & Analysis

Summary
Analysis
In Germany, there is a small valley know as Das Neandertal. Here, in the mid-19th century, workers stumbled upon the first Neanderthal remains. Since then, scientists have found Neanderthal remains in other parts of Europe and the Middle East. Neanderthals had sophisticated tools, wore animal skins to keep themselves warm, and hunted for food. Then, about 30,000 years ago, they vanished. Some researchers argue that environmental changes wiped out the Neanderthals, while others claim that Homo sapiens killed them. It’s likely, however, that Homo sapiens interbred with the Neanderthals.
So far, Kolbert has written about the role humans have played in annihilating wild animals and plants. In this chapter, however, she’ll address the role that humans may have played in wiping out their close cousins, Neanderthals—creatures who, it would seem, had big brains and complex societies. In this way, Chapter 12 paints an even bleaker portrait of human nature, suggesting that humans might have a propensity to destroy even beings that resemble themselves closely enough to interbreed.
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Kolbert visits the Max Planck Institute for Evolutionary Anthropology in Leipzig. There, she meets Svante Pääbo, the director of the department of evolutionary genetics. Pääbo pioneered “paleogenetics,” the study of ancient genetics. He hopes that, in the near future, humans will succeed in mapping the Neanderthal genome so that they can compare Homo sapiens and Neanderthal genetics side-by-side.
Kolbert introduces a new, cutting-edge field of science: paleogenetics. Under the right circumstances, it’s possible to examine prehistoric remains and find fragments of DNA. Using DNA samples, scientists like Pääbo can reconstruct what long-extinct creatures looked like, a boon to the study of mass extinction.
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At first, scientists thought that the remains of Neanderthals belonged to regular human beings. However, some specialists pointed out that the bones were bowed in unusual areas. In the coming decades, more Neanderthal bones surfaced, and researchers (or sometimes amateurs) noticed that the skeletons had unusually large skulls and unusually bowed femur bones. Early 20th century scientists portrayed Neanderthals as hairy, brutish creatures who could barely stand up straight, and this was taken as evidence of their uncivilized nature. However, after World War II, anatomists re-examined Neanderthal remains and made some striking conclusions. They decided that Neanderthals didn’t walk with a slouch, weren’t hairy, and, in fact, looked striking like modern humans. There is even some evidence that Neanderthals buried their dead and planted flowers on the graves.
This passage highlights the eagerness of scientists to distance humans from Neanderthals, an extinct species that humans may have wiped out. While science is shown throughout the book to be innovative and promising for the planet, the instances in which science falters and confirms some of humanity’s worst impulses are equally important. The dehumanization of the Neanderthal by 20th century science shows that science is only as rigorous as the humans who carry it out—when misapplied, it can simply confirm prejudices.
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DNA is often considered to be a “blueprint” for the structure of a human being. A human genome consists of billions of “lines” of four chemicals (adenine, thymine, guanine, and cytosine) housed in the nucleus of a cell. After human beings die, their genomic code deteriorates quickly, which means that it’s very difficult to find any genetic information about humans (or Neanderthals) who lived in the distant past. However, scientists have succeeded in finding genetic code in Neanderthal bones. Analysis reveals that Neanderthal DNA is very similar to human DNA, with Europeans and Asians bearing more of a resemblance to Neanderthals than Africans do.
It is extremely difficult to reconstruct an entire genome from a few strands of ancient DNA. Therefore, paleogenetics is a slow, painstaking science, and a lot of work remains to be done before scientists reassemble the Neanderthal genome. However, the close similarities between Neanderthal and human DNA suggest that the two species cannot be considered distinct, at least not simplistically—Neanderthals shape the genetics of many modern humans.
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Get the entire Sixth Extinction LitChart as a printable PDF.
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The most popular theory for how humans evolved is the “Out of Africa” hypothesis, which states that modern humans are descendants of a small population of humans who were living in African about 200,000 years ago. Most of those humans’ descendants migrated to the Middle East, followed by Europe, Asia, Australia, and the Americas. This suggests that Neanderthals were already living in Eurasia when the ancestors of modern humans traveled “Out of Africa.”
The history of the human race begins with a story of migration, “out of Africa.” This might suggest that, in some ways, humans are genetically predisposed to travel, explore, and wander, even when their current environments provide for all of their material needs.
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One problem with the “Out of Africa” account of Neanderthals is that, were it true, one might think that all living humans have the same genetic overlap with Neanderthals—but in fact, some people’s DNA has much more in common with Neanderthal DNA than other people’s DNA does. Scientists have proposed a slight modification to the Out of Africa theory—the “leaky-replacement hypothesis,” which states that early human beings interbred with Neanderthals when they first encountered Neanderthals in Eurasia. Furthermore, the fact that some Neanderthal DNA seems to have survived in human beings suggests that half-human, half-Neanderthal children were cared for, rather than being scorned or hated.
There is a lot of conflicting evidence concerning Neanderthals, but that Neanderthals and homo sapiens interbred and cared for one another’s children certainly adds complexity to the hypothesis that homo sapiens led to the extinction of Neanderthals. This would suggest that malice, or even indifference, is not necessarily the driving force of human-fuelled mass extinction—perhaps it’s a much more complicated combination of factors than we tend to intuitively assume.
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What makes humans human? One might suppose that the deciding factor is intelligence—but, of course, apes and primates show many signs of intelligence. Scientists have shown that primates can make inferences, solve puzzles, etc.—in some ways, apes are better than human children at solving complex puzzles. However, human children always outscore apes in tests designed to measure their ability to read social cues. Perhaps one part of what makes humans human, then, is the ability to engage in “collective problem-solving” — solving a problem by communicating with other people.
Human history suggests that human nature is, in part, the ability to cooperate with other people and communicate and work together as a group. It’s interesting, though, in light of Kolbert’s previous observations about 20th century scientists’ obsession with differentiating human from Neanderthal, that she focuses here on ways in which apes are lesser than humans. She has an important point, but it raises questions that Kolbert herself has asked about the eagerness of humans to differentiate themselves from the natural world.
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What were Neanderthals like? To begin with, it’s pretty clear that they made stone tools. It’s also likely that they buried their dead. Neanderthal remains betray signs of serious injuries, suggesting, perhaps, the “rigors of hunting” in Neanderthal society. Interestingly, there is evidence that Neanderthals were seriously injured, but then survived their injuries, implying that they took care of each other. Neanderthals spread across Europe, but it seems probable that they never built boats to cross bodies of water.
There is limited evidence to suggest that Neanderthals were milder and gentler than human beings. They took care of their wounded instead of leaving them to die (as in many human societies, for instance, the Greek city of Sparta). And perhaps the fact that Neanderthals built some simple tools, but never boats, suggests that they lacked the same “spark” of creativity that defines the human race.
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Pääbo has pioneered an intriguing theory about Neanderthals. It seems that restlessness, curiosity, and “mad ambition” are quintessential human qualities—and perhaps they’re genetic. Perhaps Neanderthals lacked these genetic qualities—they never developed the ambition to cross bodies of water, conquer territory, wipe out other species, etc.
Kolbert has offered many competing definitions of human nature throughout her book. Here, she suggests, once again, that ambition and drive are vital components of human nature: unlike all other living creatures, humans feel a complex, irrational desire to discover the new. Perhaps it is this irrational desire that drives humans to hunt other species into extinction, permanently alter the environment, etc.
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Pääbo has found plentiful evidence of species interbreeding in human fossils. For example, in analyzing a fossilized fragment of tooth that belonged to an early, humanoid species called the Denisovans, he concluded that it is likely that humans interbred with the Denisovans. It’s possible that the Denisovans went extinct because of their low reproductive rates, and the same is true of humans’ “next-closest kin,” apes. In the 21st century, apes are going extinct because they’re not reproducing quickly enough. In a few centuries, it’s possible that humans’ “sister species”—not just Neanderthals and Denisovans, but chimpanzees, apes, etc.—will be wiped out.
Another major reason that human beings have survived over the centuries is that they have a relatively fast reproduction rate (at least when compared with other similar species). The combination of rapid reproduction and “mad ambition” has led human beings to rule the planet, wiping out many other species, including their closest cousins, Neanderthals and Denisovans, in the process. When considering apes to be human cousins instead of simply animals, their mass extinction begins to seem more sinister.
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Kolbert drives to La Ferrassie, a French site where the largest recorded assemblages of Neanderthal remains were discovered 100 years ago. As she watches a team of paleontologists at work, she imagines what life had been like for Neanderthals. She finds a beautiful hand-ax, almost perfectly symmetrical. When she tells a paleontologist that the ax is beautiful, he points out that Kolbert is “projecting the present” onto the past; in other words, there’s no evidence that Neanderthals designed their tools to be beautiful. Indeed, no remains of Neanderthal art or adornment have yet been discovered.
So far, one could argue that Kolbert has taken “the Neanderthals’ side”—she has characterized Neanderthals as peaceful, compassionate beings, as compared to human beings, their more brutal, ambitious relatives. But in this passage, Kolbert emphasizes some of the limitations of Neanderthal society. Neanderthals may not have been brutal, aggressive animals, but they also made no art. By the same token, humans may be brutal, greedy creatures, but they’re also capable of producing cave paintings, and other things of great beauty. This passage also illustrates the interpretive dangers of viewing the whole world through a human-centric lens.
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On her last day in France, Kolbert visits another archeological site, Grotte des Combarelles. There, she enters a cave where human beings once lived—on the walls, there are sketches and paintings. It occurs to Kolbert that prehistoric human beings must have been “a little bit mad” to go exploring the caves armed only with fire and axes. Perhaps if humans, with their madness, their ambition, and their “signs and symbols,” had never existed, Neanderthals would still be around.
Ultimately, Chapter 12 portrays human nature as a set of contradictions. Humans are “madly ambitious,” but also heroic and artistic in their curiosity. In a Greek tragedy, the hero’s greatest strength—his or her intelligence, ambition, or wisdom—is usually also his or her fatal flaw, and one could say exactly the same about the human race as Kolbert portrays it in this book. Our incessant desire to explore the world and create civilization will also be our undoing.
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