The Origin of Species · Chapter
Single Centres of Supposed Creation explained
Darwin argues that each species likely originated in a single region and then migrated, rather than being created at multiple points.
What happens
Darwin argues that each species likely originated in a single region and then migrated, rather than being created at multiple points. He addresses difficulties in explaining the distribution of species across distant and isolated areas, emphasizing the role of barriers, migration, and geological changes. He previews three classes of facts that challenge this view: species on mountain summits, freshwater productions, and terrestrial species on islands.
Themes in this chapter
Geographical Distribution and Barriers
Darwin discusses how barriers like oceans limit migration, explaining why mammals are not shared between distant continents, while plants with better dispersal mechanisms are.
Common Descent and the Tree of Life
The chapter emphasizes that species of a genus are descended from a common progenitor and have migrated with modification, supporting the principle of descent with modification.
Characters to notice
- Mr. Wallace
Darwin references Wallace's conclusion that every species has come into existence coincident with a preexisting closely allied species, attributing this to descent with modification.
Key passages
“If the existence of the same species at distant and isolated points of the earth’s surface can in many instances be explained on the view of each species having migrated from a single birthplace; then, considering our ignorance with respect to former climatical and geographical changes, and to the various occasional means of transport, the belief that a single birthplace is the law seems to me incomparably the safest.”
If we can explain how the same species appears in distant places by migration from one origin, then given our limited knowledge of past climate and geography, the idea of a single birthplace is the most reliable.
Darwin defends the single-center hypothesis as the most parsimonious explanation for species distribution.
“The great and striking influence of barriers of all kinds, is intelligible only on the view that the great majority of species have been produced on one side, and have not been able to migrate to the opposite side.”
The clear effect of barriers makes sense only if most species originated on one side and couldn't cross to the other.
Darwin uses barriers to argue against multiple centers of creation.