Themes
Key
LitCharts assigns a color and icon to each theme in The Beak of the Finch, which you can use to track the themes throughout the work.
Natural Selection and Evolution as Ongoing Processes
Nature and Humanity
Evolution, the Modern Era, and Nature’s “Resistance Movement”
The Interconnectedness of Species and Ecosystems
Hybridization and Specialization
Summary
Analysis
Martin Taylor, a researcher in the Grants’ subterranean lab at Princeton, receives huge shipments of moth specimens every day from all across the U.S.’s Cotton Belt. He grinds the moths up in a mortar and pestle to extract their DNA. Taylor is studying the moths because they have, over the years, developed a peculiar and stunning resistance to pesticides. The moths that were able to tolerate initial sprayings of DDT in the 1940s passed on their genes to their offspring—and now, no matter how big the dose of DDT, the moths are able to survive it. The moths have developed resistances to other pesticides, as well. The pesticides’ inability to kill the moths, which feed on cotton, is panicking farmers across the region. It’s also an example of “visible evolution.”
Evolution isn’t just happening in the Galápagos—it’s taking place around the world, especially in spots where humanity is putting intense selective pressures on the species around them. In the case of the Cotton Belt’s moths, humanity’s attempt to stop the creatures from being able to evolve is actually the very fuel the species needs to carve out new niches for itself and find new ways to survive. By ignoring the effects we have on the species around us, humanity is only frustrating itself.
Themes
Other insects, too, are rapidly developing complete immunity to commercially available pesticides. Some insects have evolved chemical antidotes to pesticides, or ways of dodging the poison such as by letting a poison-afflicted appendage fall from their body. These evolutionary mechanisms can develop over the course of a single growing season, which also spans multiple generations of the insects.
This passage depicts the process of evolution in action. By presenting a threat to a species’ survival, humanity unwittingly ensures that the threat pressurizes the species in question to develop ways to survive. In other words, the more humanity does to control a species, the more adaptable and thus uncontrollable the species will become.
Themes
By studying the moths’ DNA, Taylor is working to determine how, biologically, the insects are resisting—and what this might mean for other species with which they share DNA. The moth’s gene that allows it to resist the pesticide is the same gene that many pesticide-resistant flies have—which shows that these “fixed categories” of different species are not as fixed as certain people (cotton farmers, especially) would like to think.
The physical and behavioral effects of evolution can be seen with the naked eye—but there are still stories to be told in an organism’s DNA that reveal even more about the minutiae of the evolutionary process. By looking at animals like these moths on a molecular level, scientists can develop a greater understanding of how these extraordinary specializations are taking place.
Themes
“Resistance movements” like this one are happening throughout the natural world. After the arrival of antibiotics in western hospitals in the 1950s, antibiotic-resistant bacteria appeared within just a year. Now, antibiotic resistance is being termed a “global epidemic.” Bacteria like E. coli grow so rapidly that when dosed with an antibiotic, the few surviving cells in the colony are able to replace their lost numbers within a day or two. The insides of a human body, then, becomes a site of natural selection and evolution in progress.
This passage shows that the forces of natural selection and evolution are strong enough to create a “global epidemic” that could one day change the course of the wider evolutionary process forever. Bacteria are simpler life forms that crop up in extraordinary numbers, so scientists can watch their evolutionary behaviors unfold even more quickly than naturalists can observe them happening in finches or guppies. Natural selection and evolution aren’t just taking place in the wild—because of bacteria, they’re processes that are even taking place within us. Again, this passage suggests that humanity must recognize the role we play in the evolutionary processes of the species around (and indeed within) us.
Themes
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Investigators have fully mapped the genetic sequences of many kinds of viruses—but the sequences of viruses are always changing. Viruses evolve at a mutation rate of about a million times the rate of the human body—the weapon of the virus, Weiner writes, “is variation itself.” And viruses are constantly evolving—they are “our only real competition for domination of the planet,” says one microbiologist. The harder we attack bacteria through antibiotics, viruses through therapeutics, or cancers through chemotherapy, the more ably these rapidly growing resistance cells evolve. In other words, “whenever we aim at a species point-blank […] we drive its evolution.”
The quotation that appears at the end of this passage is significant, because it illustrates that the natural world is evolving directly in response to humanity’s attempts to control it. By “aim[ing]” at a species directly, humanity influences how that species evolves. The species will almost always try to get out of the way of humanity’s range and thus ensure its survival—so anything we do to attack nature will, ironically, often result in nature growing stronger and finding new ways to evolve out of our metaphorical sights.
Themes
Elephants in regions of Africa where poaching is common have begun to evolve to be tusk-less. In order to protect the resource that humanity is “point-blank” trying to take from them, they are evolving in a way that’s detrimental to their short-term well-being but essential to their long-term survival. The same kind of things are taking place in fisheries. Fish are becoming smaller, since bigger fish are the ones prized by fishermen and the consumers they sell to.
This passage confirms that animals are adapting and evolving in order to survive humanity’s attempts to cull their numbers. Animals with traits that are less desirable are becoming more common, because being insufficient prey for humanity is now an advantageous trait.
Themes
The moths are evolving at a rate faster than what Taylor can keep up with. But farmers are still trying to shoot at them “point-blank.” Ironically, the more preventative spraying these farmers do, the more capably they arm the evolving moths against their attacks. The more pressure humanity places on bacteria or moths or fish, the more we force them to evolve around that pressure. What humans call “control” is merely, to these organisms, a change that must be met, and a challenge to which they must rise.
The book underscores that evolution is real, and it will, given the chance, undermine any attempt to control it. Humanity must recognize that evolution is happening in order to work with and understand it. Only by realizing how our actions impact the species around us will we be able to work with rather than against the evolutionary processes happening all around us.
Themes
