The Origin of Species · Chapter
Circumstances Favourable to Man’s Power of Selection explained
Darwin discusses the factors that enhance or hinder artificial selection by humans, emphasizing the importance of variability, large population numbers, careful attention to desirable traits, and the ability to control breeding.
What happens
Darwin discusses the factors that enhance or hinder artificial selection by humans, emphasizing the importance of variability, large population numbers, careful attention to desirable traits, and the ability to control breeding. He notes that domesticated varieties often differ more among themselves than natural species do, and concludes that selection—whether methodical or unconscious—is the predominant force in the origin of domestic races.
Themes in this chapter
Domestication and Artificial Selection
The chapter focuses on how human selection, aided by factors like variability and population size, drives the formation of domestic breeds.
Variation and Inheritance
Darwin discusses variability as the raw material for selection, and the role of inheritance and reversion in determining which variations persist.
Characters to notice
- Charles Darwin
Author and narrator, presenting observations on artificial selection.
- Mr. Wallace
Referenced for his remark that a limit to variation will eventually be reached.
- Geoffroy Saint-Hilaire
Cited for proving that domestic varieties differ more in size than distinct species of the same genus.
Key passages
“A high degree of variability is obviously favourable, as freely giving the materials for selection to work on; not that mere individual differences are not amply sufficient, with extreme care, to allow of the accumulation of a large amount of modification in almost any desired direction.”
A lot of variation is helpful because it provides raw material for selection, but even small individual differences can, with careful attention, lead to significant changes over time.
Darwin emphasizes that variability aids selection, but is not strictly necessary for gradual modification.
“But probably the most important element is that the animal or plant should be so highly valued by man, that the closest attention is paid to even the slightest deviations in its qualities or structure.”
The key factor is that humans must value the organism enough to notice and act on even tiny differences.
Attention to detail is crucial for effective artificial selection.
“Over all these causes of change, the accumulative action of selection, whether applied methodically and quickly, or unconsciously and slowly, but more efficiently, seems to have been the predominant power.”
Selection—whether done deliberately and rapidly, or unintentionally and gradually—is the most important force driving change in domestic species.
Darwin concludes that selection is the dominant mechanism in domestication.