The Origin of Species · Chapter
Inherited Changes of Habit or Instinct in Domesticated Animals explained
Darwin examines how instincts and habits in domesticated animals are inherited and modified through habit, selection, and crossbreeding.
What happens
Darwin examines how instincts and habits in domesticated animals are inherited and modified through habit, selection, and crossbreeding. He argues that both natural instincts can be lost and new ones acquired under domestication, often through a combination of compulsory habit and unconscious or methodical selection. Examples include pointing in dogs, tameness in rabbits, and the loss of broodiness in fowls.
Themes in this chapter
Domestication and Artificial Selection
Central theme: how human selection and habit modify instincts in domestic animals.
Variation and Inheritance
Inherited variations in mental qualities and instincts are key to the chapter's argument.
Adaptation and the Utilitarian Doctrine
Instincts are shaped by utility, as seen in pointing and retrieving behaviors.
Characters to notice
- Charles Darwin
Author and observer, presents personal observations of pointing dogs and tumbler pigeons.
- Mr. Hudson
Cited for observations on cat instincts and inherited tendencies.
- Mr. Brent
Provides information on house-tumblers near Glasgow.
- Captain Hutton
Reports on the wildness of young Gallus bankiva chicks in India.
- Le Roy
Describes a dog with wolf ancestry showing a trace of wild instinct.
Key passages
“When the first tendency to point was once displayed, methodical selection and the inherited effects of compulsory training in each successive generation would soon complete the work; and unconscious selection is still in progress, as each man tries to procure, without intending to improve the breed, dogs which stand and hunt best.”
Once a dog first showed a tendency to point, deliberate breeding and the inherited results of forced training across generations quickly perfected the behavior, and unconscious selection continues as owners seek dogs that point and hunt well without aiming to improve the breed.
Darwin illustrates how artificial selection and habit combine to refine instinctive behaviors.
“On the other hand, habit alone in some cases has sufficed; hardly any animal is more difficult to tame than the young of the wild rabbit; scarcely any animal is tamer than the young of the tame rabbit; but I can hardly suppose that domestic rabbits have often been selected for tameness alone; so that we must attribute at least the greater part of the inherited change from extreme wildness to extreme tameness, to habit and long-continued close confinement.”
In contrast, sometimes just habit is enough; wild rabbit kits are extremely hard to tame, while tame rabbit kits are extremely tame, yet I doubt that tameness alone was selected for, so the inherited shift from wild to tame must be largely due to habit and prolonged confinement.
Darwin argues that habit, not just selection, can produce inherited behavioral changes.
“Hence, we may conclude that under domestication instincts have been acquired and natural instincts have been lost, partly by habit and partly by man selecting and accumulating, during successive generations, peculiar mental habits and actions, which at first appeared from what we must in our ignorance call an accident.”
Thus, in domestic animals, new instincts are gained and old ones lost through a mix of habit and human selection over generations, starting from accidental variations.
Summary of Darwin's conclusion on the dual role of habit and selection in instinct modification.