A fascination with domestication
Throughout his working life, Darwin retained an interest in the history, techniques, practices, and processes of domestication. Artificial selection, as practiced by plant and animal breeders in the mid-nineteenth century, offered a ready and obvious model of how speciation under natural selection may have taken place. Therefore, Darwin studied the work of cattle, sheep, and dog breeders. Additionally, Darwin corresponded with humble pigeon fanciers and famous botanists alike, including W. B. Tegetmeier, the poultry editor for the Livestock Journal and Fancier’s Gazette, and his close friend Asa Gray, head of the botany program at Harvard University.
Pigeons as a window into variation
Darwin homed in on pigeons as a prime example of the processes of speciation and of the extent of variation among domestic species. He included a chapter on pigeons in On the Origin of Species, and two chapters on pigeons in The Variation of Plants and Animals Under Domestication. From his correspondence on the subject, we learn that Darwin himself bred pigeons in an effort to understand the process and the extent of variation under domestication. Nonetheless, Darwin relied on the advice of experts like Tegetmeier, as well as the assistance of naturalists in other countries—many of whom shared their observations and even their specimens with Darwin—in order to collect all the facts he wanted on pigeons for On the Origin of Species.
You can download the entire packet of reading materials here: Variation under domestication source pack
Darwin, Charles. On the Origin of Species. 1859. London: John Murray. (Chapter I "Variation under domestication")
Letter 1651—Darwin to Fox, W.D., 19 March 
Darwin writes to his second cousin, William Darwin Fox, to ask him to observe at what age pigeons' tail-feathers are sufficiently developed to be counted. Darwin believes this information will add to the notes he his collecting for a book with all the facts “for & versus” the immutability of species.
Letter 1686—Darwin to Fox, W.D., 23 May 
In this letter, Darwin writes to his second cousin Fox to tell him about his own efforts to breed pigeons. Darwin is particularly interested to know whether the offspring of domestic pigeons show as much variation as their parents do.
Letter 1788—Darwin to Tegetmeier, W.B., [2 Dec 1855]
In this letter Darwin writes to Tegetmeier, a pigeon fancier. He tells Tegetmeier that he is collecting examples of pigeons and poultry and would be be particularly grateful for any rare breeds that Tegetmeier could send him.
Letter 1794—Darwin to Layard, E.L., 9 Dec 1855
Darwin writes to Edgard Layard, a civil servant working in South Africa, about his work to collect all facts regarding the variation and origin of species. Darwin asks if Layard would send skins of local Good Hope poultry so that Darwin might add to his store of information on the variation present in domestic species.
Letter 1837—Darwin to Thwaites, G.H.K. 8 Mar 1856
Darwin writes to George Thwaites, a botanist and superintendent of the botanic gardens in Ceylon. He asks if Thwaites will send him skins of Indian or Ceylon breeds of pigeons, in order that Darwin might add them to his study of the variation of domestic breeds.
1. How does Darwin address Tegetmeier in his letters? How do you think he perceives Tegetmeier's expertise?
2. Does Darwin incorporate the work of other pigeon fanciers into his discussion on pigeons in the first chapter of the Origin? How can you tell?
3. What is Darwin's primary theory on how variation works under domestication? Why does the context of domestication matter to him?
In order to further explore Darwin's work with pigeons, we suggest investigating this web resource dedicated to Darwin's experiments with pigeons:
If possible we also suggest contacting a pigeon fancier in your area. You may be able to arrange a visit to their pigeon farm. If you are able to visit a pigeon fancier, have your students observe differences in morphology and behavior and discuss breeding decisions with the fancier!
Links to pigeon fancier organizations:
Here's an example of a Harvard class outing at a pigeon fancier's farm:
While studying the importance of variation under domestication to Darwin’s On the Origin of Species (1859), the class went on a field trip to a pigeon fancier. Pigeon fanciers typically breed pigeons for competition. Among other things, pigeons compete on their appearance, speed, and ability to tumble through the air rapidly. The pigeon fancier the class visited breeds Birmingham roller pigeons. These pigeons compete on the basis of their ability to tumble through the air in a group. During this field trip the students learned about and observed the vast array of phenotypic expressions that can be achieved within a single pigeon breed through artificial selection; the pigeons varied in their plumage, coloring, and size.
If you don’t have access to a pigeon fancier, there are many other ways to gain an appreciation for the importance of variation under domestication to Darwin’s theory of natural selection. For example, you could visit a dog, cat, or horse breeder. Before visiting the breeder, have your students read Darwin’s work on pigeons and the first chapter of On the Origin of Species. At the breeder, your students will have the opportunity to make their own observations of the power of artificial selection.