The Origin of Species · Chapter
Acclimatisation explained
Darwin explores the capacity of species to adapt to different climates, arguing that acclimatisation is a product of both habit and natural selection.
What happens
Darwin explores the capacity of species to adapt to different climates, arguing that acclimatisation is a product of both habit and natural selection. He presents evidence from plants and animals, including observations by Hooker, Thwaites, and Watson, and discusses the flexibility of constitution common to many organisms, concluding that natural selection of innate variations often overrides the effects of habit.
Themes in this chapter
Adaptation and the Utilitarian Doctrine
Discusses how species are adapted to their climates and the role of natural selection in preserving individuals with constitutions best suited to their environment.
Natural Selection and the Struggle for Existence
Explores natural selection's role in acclimatisation, preserving innate variations that confer hardiness.
Variation and Inheritance
Highlights hereditary variation in plants (e.g., flowering period, seed germination) and the appearance of hardier seedlings in kidney-beans.
Characters to notice
- Dr. Hooker
Provided evidence of pines and rhododendrons from different Himalayan altitudes showing varying cold resistance.
- Mr. H. C. Watson
Observed acclimatisation in European plants brought from the Azores to England.
- Charles Darwin
Author of the chapter, presenting arguments and observations on acclimatisation.
Key passages
“Habit is hereditary with plants, as in the period of flowering, in the time of sleep, in the amount of rain requisite for seeds to germinate, etc.”
Plants inherit habits such as when they flower, when they rest, and how much rain they need to sprout.
Introduces the concept of hereditary habits in plants.
“We have reason to believe that species in a state of nature are closely limited in their ranges by the competition of other organic beings quite as much as, or more than, by adaptation to particular climates.”
The ranges of wild species are often restricted more by competition with other organisms than by climate alone.
Highlights the role of biotic interactions in limiting species distribution.
“On the whole, we may conclude that habit, or use and disuse, have, in some cases, played a considerable part in the modification of the constitution and structure; but that the effects have often been largely combined with, and sometimes overmastered by, the natural selection of innate variations.”
Overall, habit and use/disuse sometimes modify an organism's constitution, but natural selection of inborn variations usually plays a larger role.
Summarises Darwin's conclusion on the relative importance of habit versus natural selection in acclimatisation.