49 pages • 1 hour read
Elizabeth KolbertThe Sixth Extinction: An Unnatural History (2014)
Nonfiction | Book | Adult | Published in 2014A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Chapters 12-13 Chapter Summaries & Analyses
Chapter 12 Summary: “The Madness Gene: Homo neanderthalensis”
Kolbert begins the chapter with a brief history of the Neanderthal, starting with the first discovery of Neanderthal bones in the Neander Valley of Germany in 1856. Many more Neanderthal bones have been found over time, from as far away as Wales to Israel to eastern Europe. Numerous tools have been unearthed, and evidence has been found that Neanderthals, due to the colder temperatures of Europe, wore some kind of clothing and built shelters.
The Neanderthals, however, fell prey to a new species, one that has had a role in the extinction of many others: modern humans. With every place that modern humans moved to, the Neanderthals in those areas disappeared. Humans had sex with Neanderthals, and as Kolbert notes, “up to four percent” of people alive today have some Neanderthal ancestry (237). But ultimately, Neanderthals lost out to the homo sapiens who moved into their territories.
At the Max Planck Institute for Evolutionary Anthropology in Leipzig, Kolbert meets Svante Paabo, the Swedish head of the department of evolutionary genetics. Paabo is considered the “father of paleogenetics,” as he is responsible for developing the study of ancient DNA. His past work involved obtaining genetic information from Tasmanian tigers, giant ground sloths, and Egyptian mummies. More recently, he has been working on sequencing the Neanderthal genome.
Kolbert notes that it is much easier to sequence the genomes of species that are alive, and more difficult to sequence the dead. When an organism dies, “its genetic material begins to break down, so that instead of long strands of DNA, what’s left, under the best of circumstances, are fragments” (239). Paabo’s project, when finished, will allow human and Neanderthal genomes to be examined together, to determine exactly when and where they overlapped. Paabo believes that this study will enable him to discover a genetic basis for why humanity has been able to develop and spread around the world as it has, and to create technologies with which to dominate the globe.
The original bones found in a quarry in the Neanderthal Valley were nearly mistaken for the bones of a bear and thrown out in the garbage. The quarry owner took the bones and gave them to a schoolteacher who was a part-time fossilist. The teacher, Johann Carl Fuhlrott, realized that the bones resembled those of a human, probably a “primitive member of our race” (241). Darwin’s On the Origin of the Species was published at this time, and many scientists dismissed Fuhlrott’s hypothesis, believing the bones had belonged to a human person.
But as more bones and skulls continued to be found in the valley, more scientists had to take into consideration that Fuhlrott’s theory may have had merit. Some scientists and artists imagined the Neanderthal to be a stooped, bow-legged creature with an ape-like skull and a hairy body. With further studies in the 1950s, scientists determined that the Neanderthal posture was probably due to arthritis, but that otherwise, in appearance, this species was similar to humans. A discovery of more Neanderthal bones in an Iraqi cave in the 1960s proved that Neanderthals cared for injured members of their societies, and buried those members that they lost, including interring them with flowers.
Paabo’s genome project did indeed show that Neanderthals and humans were similar in their genetic sequences, but it also uncovered some new information. The Neanderthal DNA was more related to humans from Europe and Asia than to those from Africa. This proof forced scientists to rethink the theory of a single origin of humanity in Africa two hundred thousand years ago. Modern humans expanded around the world, driving Neanderthals and other archaic humans to extinction. But, as Paabo notes, Neanderthals aren’t entirely gone: “they live on a little bit in us” (246).
Kolbert poses the questions of what makes us human, and asks how we are different from apes. She believes that understanding social cues, collaborative teamwork, and group projects separate us from nonhuman apes like chimpanzees. What Paabo is amazed by is the daring that early humans exhibited in traveling beyond the oceans. As he explains, “We are crazy in some way. What drives it? That I would really like to understand” (251).
Kolbert then turns to the great mountain and lowland apes that face extinction today. The major causes of their impending disappearance are “poaching, disease, and habitat loss” (253), all caused by humans. At the rate humans are destroying their sister species, Kolbert theorizes that at some point soon, humans will be the only representatives left of the great apes.
In La Ferrassie, France, Kolbert visits the spot where one of the largest caches of Neanderthal bones has even been found. With a team of archaeologists, Kolbert examines bones that remain in what is left of the La Ferrassie limestone cave. She asks the students at the site what life must have been like for Neanderthals, and they respond that life would have been full of hunger, cold, and pungent smells. It is incredible to Kolbert, then, that a small genetic variation separated Neanderthals from humans, making the former extinct and the latter powerful enough to create as well as to destroy.
Chapter 13 Summary: "The Thing With Feathers: Homo sapiens”
In San Diego, Kolbert goes to the Institute for Conservation Research, a part of the city’s zoo. There she sees two vials that contain all that is left of the black-faced honeycreeper, or po’ouli, a bird that went extinct in 2004 despite the zoo’s best efforts to save it. When the last bird was captured and died shortly after that, the corpse was rushed to the zoo so that cells from the bird’s eye could be cultured for future attempts to bring the species back.
Kolbert cites examples of humanity’s attempts to preserve species that it has, in various ways, driven to the brink of nonexistence. The Act for the Preservation of Sea Birds, the creation of Yosemite National Park, and the passage of the Endangered Species Act in 1974, are all instances that Kolbert references, as well as the comeback of bald eagles and condors. She argues that it is better to think of what humans can do “better, practically and ethically to focus on what can be done and is being done to save species” than to bemoan species that are already gone or on the verge of disappearing (262).
At the conservation center, Kolbert sees a Hawaiian crow, an alala, named Kinohi. He is one of only one hundred of these crows alive, all of which are kept in captivity. The alala have suffered from population loss because of invasive species, habitat loss, and disease. Kinohi is an example of an alala raised in isolation, and as such, he doesn’t recognize any other alala. He ended up at the San Diego Zoo because he wouldn’t mate with any captive crows. Now humans are desperately trying to use Kinohi’s sperm to inseminate a female crow artificially.
Kolbert argues that, as destructive as humans can be, we can also go to extreme lengths to undo the damage we’ve caused: “Such is the pain the loss of a single species causes that we’re willing to perform ultrasounds on rhinos and handjobs on crows” (263).
At the American Museum of Natural History’s Hall of Biodiversity, Kolbert mentions an exhibit on the floor that displays the five major extinction events followed by an observation: “Right now we are in the midst of the Sixth Extinction, this time caused solely by humanity’s transformation of the ecological landscape” (266). This display suggests that humanity itself may be undone by “our transformation of the ecological landscape” (266). Humanity, the probably cause of the Sixth Extinction, may well be the victim of it, too. It is humanity’s destiny to determine what species will live and which ones will die, a responsibility that Kolbert calls “our most enduring legacy” (267).
Chapters 12-13 Analysis
In the final two chapters of the book, Kolbert focuses on the development of human beings, our ancient ancestors, and the role humans have played in the species extinctions that may happen shortly.
Kolbert traces the history of the Neanderthal, from the discovery of the first bones to the newest scientific projects mapping out the genome structure and comparing it to that of Homo sapiens. At some point, scientists believe that the two species intermingled and that eventually, in some genetic fashion, humans caused the Neanderthal and other sister species to go extinct.
Kolbert ends her book with some hope that even though human beings may be mostly—if not entirely—responsible for a sixth extinction event, we are also working hard to reverse what damage we can and to save or recover species that are endangered or near total extinction.
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