Themes
Key
LitCharts assigns a color and icon to each theme in The Origin of Species, which you can use to track the themes throughout the work.
Natural Selection and the Power of Nature
Reason, Argument, and the Scientific Method
Time and Progress
Collaboration and Science
Summary
Analysis
Darwin wrote about the structure of his book, and how before continuing the ideas of the first chapter, the second chapter would look at whether organic beings out in nature (as opposed to in domestication) were subject to a similar variation. Darwin acknowledged that there were reasons to doubt that variations would survive in wild populations, and promised to explore the issue in more detail in a later chapter.
Darwin structures his arguments methodically, both giving previews of topics he’ll cover as well as summarizing them afterwards. He now begins the transition from talking about domestic animals to talking about wild populations of animals, which are really the main focus of his theories.
Themes
Individual Differences. Darwin described how offspring from the same parents showed slight differences. Many naturalists considered these details as only affecting unimportant parts of organisms, and while Darwin acknowledged that this was often the case, he believed that his own experience and the work of other naturalists suggested that in fact, variations often affected important parts of animals, like interior organs and nerves. Even skeptics acknowledged that there was often wide variation between male and female offspring, with the different sexes having different forms.
Again, Darwin’s observations were held back by a general lack of knowledge about genetics during the time period when he was writing. Nevertheless, in spite of this limitation, Darwin analyzed the reproductive process in a methodical way and was able to draw important insights about how variations among offspring were affected by seemingly random chance and by sex.
Themes
Doubtful Species. Darwin wrote about the criteria for determining whether different forms of a particular animal or plant were a new species or just variation within a species. In many cases, this distinction was simply decided by a majority of naturalists, although many accepted classifications had dissenters, and some classification cases presented complicated difficulties. Botanists in Britain, France, and the U.S., for example, often disagreed on how many types of flora their countries contained, with counts differing by the dozens.
Though Darwin does not believe that the boundary between species and variation is totally arbitrary, he nevertheless questions current methods of classification at times. Ultimately, he argues that natural selection does not necessarily follow the orderly classification systems imposed by humans, and that is why classification systems sometimes contain flaws.
Themes
When Darwin compared his experience with American birds versus the birds on the Galapagos Islands (which he saw during his time traveling with the Beagle), he found that the distinction between varieties and species often seemed arbitrary. Darwin gave an overview of many other organisms where the boundary between species and variety was contested by naturalists.
Visiting the Galapagos Islands was a formative experience for Darwin. As he describes, he was able to see the diversity of life firsthand. Because of their isolated geography, islands often contain unusual species that would not be found on mainlands, and which helped Darwin develop his theories.
Themes
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Darwin explained how young naturalists tended to prefer categorizing things as new species in order to emphasize and account for the differing traits. He believed, however, that naturalists with a wider range of experience, particularly with global specimens, seemed to be more inclined to recommend fewer species (which have several varieties within them).
Darwin believes that people with more experience are more likely to see similarities between different organisms and, as a result, to recognize broad patterns and categorize them more accurately.
Themes
While some naturalists might not see minor differences within a species as especially significant, Darwin argued that these little differences were extremely important to his theories, since he believed in adaptations that came from an accumulation of little changes over time. Not all little variations eventually lead to a new species: some become extinct or remain as simply varieties for a long time. Ultimately, Darwin found that terms like “species” and “variety” are somewhat arbitrary, and while they can be useful in indicating the degree of difference (with “species” signifying bigger differences), in essence the terms mean the same thing.
Darwin emphasizes that for his theories, even seemingly small details are nevertheless extremely important. He acknowledges that many small differences don’t matter, and that some of them lead to negative changes that cause extinction. Still, natural selection is based on the idea that small variations can add up over time to create major adaptations, and so even minor variations are important to notice and classify correctly.
Themes
Literary Devices
Wide-ranging, much-diffused, and common Species vary most. Darwin began this new section by writing that, although the topics deserve greater detail, he would attempt to briefly explore issues related to the “struggle for existence” and “divergence of character.” He found that with plants in a given country, the species that flourish the most are often also the ones that are the most widely distributed. This widely spread species often yields offspring that have slight modifications that help them survive in specific environments. This is why wide-ranging species have the most variety.
Darwin makes the relatively common-sense argument that a species that ranges widely must be able to survive in a wide variety of environments. He goes on to suggest that over this wide range, there might be varieties of the species with adaptions that help specimens survive in their more specific local environments.
Themes
Species of the Larger Genera in each Country vary more Frequently than the Species of the Smaller Genera. Similar to the last section, genera with many species in them have more variety in them. Darwin admitted that this wasn’t the most surprising finding, but argued that it wasn’t a given and that it required a close look at the data to see this fact. Darwin found this out by comparing plants and tables of genera and species from his own collections.
It makes sense that genera with more species in them would have more variety in them, but Darwin sometimes takes time to establish the obvious point, because sometimes what seems obvious or intuitive is not actually accurate and the reality is more complicated (even though that isn’t the case here).
Themes
Many of the Species included within the Larger Genera resemble Varieties in being very closely, but unequally, related to each other, and in having restricted ranges. Darwin noted that, as any naturalist would admit, the different species within a genus are not equally distinct. Amid all the variety, there are clusters and sub-groups of species that are actually quite similar to each other. One of the key points of difference between these similar species is that they often have limited geographic ranges.
Most of what Darwin says here was common knowledge among naturalists, but Darwin explains it under the presumption that many in his audience are not trained naturalists. He emphasizes the idea that classification is not a one-size-fits-all system and that even the most organized system can struggle to account for the full variety of nature.
Themes
Summary. Darwin concluded that it wasn’t possible to distinguish varieties from species, at least not without going through a complicated classification system.
Darwin reiterates that, while human classification systems are helpful for the study of nature, these classification systems don’t necessarily reflect what actually happens in nature.
Themes
