The Origin of Species · Chapter
Circumstances Favourable for the Production of New Forms Through Natural Selection explained
Darwin examines the conditions that promote the formation of new species via natural selection, emphasizing the roles of variability, population size, inheritance, isolation, and intercrossing.
What happens
Darwin examines the conditions that promote the formation of new species via natural selection, emphasizing the roles of variability, population size, inheritance, isolation, and intercrossing. He argues that natural selection acts slowly and intermittently, that isolation can aid divergence but is not strictly necessary, and that large, open areas may be more conducive to producing enduring, widely distributed species than small isolated ones.
Themes in this chapter
Natural Selection and the Struggle for Existence
Central theme: Darwin details how variability, inheritance, isolation, and intercrossing influence the rate and success of natural selection in producing new forms.
Characters to notice
- Charles Darwin
Author and narrator; presents his reasoning on the factors favoring natural selection.
- Moritz Wagner
Cited for his essay on isolation; Darwin disagrees with Wagner's claim that migration and isolation are necessary for speciation.
Key passages
“Though nature grants long periods of time for the work of natural selection, she does not grant an indefinite period; for as all organic beings are striving to seize on each place in the economy of nature, if any one species does not become modified and improved in a corresponding degree with its competitors it will be exterminated.”
Natural selection operates over long but finite timescales; a species that fails to adapt as well as its rivals will be driven to extinction.
Highlights the competitive pressure driving natural selection and extinction.
“Slow though the process of selection may be, if feeble man can do much by artificial selection, I can see no limit to the amount of change, to the beauty and complexity of the coadaptations between all organic beings, one with another and with their physical conditions of life, which may have been effected in the long course of time through nature's power of selection, that is by the survival of the fittest.”
Even though natural selection is slow, the cumulative changes over vast periods can produce extraordinary complexity and adaptation, far exceeding what humans achieve through artificial selection.
Darwin's concluding reflection on the boundless potential of natural selection over deep time.