Animal Coloration - History

History

Animal coloration has been a topic of interest and research in biology for centuries.

In his 1665 book Micrographia, Robert Hooke describes the "fantastical" (structural, not pigment) colours of the Peacock's feathers:

The parts of the Feathers of this glorious Bird appear, through the Microscope, no less gaudy then do the whole Feathers; for, as to the naked eye 'tis evident that the stem or quill of each Feather in the tail sends out multitudes of Lateral branches, ... so each of those threads in the Microscope appears a large long body, consisting of a multitude of bright reflecting parts.
... their upper sides seem to me to consist of a multitude of thin plated bodies, which are exceeding thin, and lie very close together, and thereby, like mother of Pearl shells, do not onely reflect a very brisk light, but tinge that light in a most curious manner; and by means of various positions, in respect of the light, they reflect back now one colour, and then another, and those most vividly. Now, that these colours are onely fantastical ones, that is, such as arise immediately from the refractions of the light, I found by this, that water wetting these colour'd parts, destroy'd their colours, which seem'd to proceed from the alteration of the reflection and refraction. —Robert Hooke

According to Charles Darwin's 1859 theory of natural selection, features such as coloration evolved by providing individual animals with a reproductive advantage. For example, individuals with slightly better camouflage than others of the same species would, on average, leave more offspring. In his Origin of Species, Darwin wrote:

When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather, and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey; and hawks are guided by eyesight to their prey, so much so, that on parts of the Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence I can see no reason to doubt that natural selection might be most effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant. —Charles Darwin

Henry Walter Bates's 1863 book The Naturalist on the River Amazons describes his extensive studies of the insects in the Amazon basin, and especially the butterflies. He discovered that apparently similar butterflies often belonged to different families, with a harmless species mimicking a poisonous or bitter-tasting species to reduce its chance of being attacked by a predator, in the process now called after him, Batesian mimicry.

Edward Bagnall Poulton's 1890 book The Colours of Animals, their meaning and use, especially considered in the case of insects argued the case for three aspects of animal coloration that are broadly accepted today but were controversial or wholly new at the time. It strongly supported Darwin's theory of sexual selection, arguing that the obvious differences between male and female birds such as the Argus pheasant were selected by the females, pointing out that bright male plumage was found only in species "which court by day". The book introduced the concept of frequency-dependent selection, as when edible mimics are less frequent than the distasteful models whose colours and patterns they copy. In the book, Poulton also coined the term aposematism for warning coloration, which he identified in widely differing animal groups including mammals (such as the skunk), bees and wasps, beetles, and butterflies.

Abbott Handerson Thayer's 1909 book Concealing-Coloration in the Animal Kingdom, completed by his son Gerald H. Thayer, argued correctly for the widespread use of crypsis among animals, and in particular described and explained countershading for the first time. However, the Thayers spoilt their case by arguing that camouflage was the sole purpose of animal coloration, which led them to claim that even the brilliant pink plumage of the flamingo or the roseate spoonbill was cryptic — against the momentarily pink sky at dawn or dusk. As a result, the book was mocked by critics including Theodore Roosevelt as having "pushed to such a fantastic extreme and to include such wild absurdities as to call for the application of common sense thereto."

Hugh Bamford Cott's 500-page book Adaptive Coloration in Animals, published in wartime 1940, systematically described the principles of camouflage and mimicry with hundreds of examples, over a hundred illustrations — both photographs and his own accurate and artistic drawings, and 27 pages of references. Cott focussed especially on "maximum disruptive contrast", the kind of patterning used in military camouflage such as disruptive pattern material. Indeed Cott describes such applications:

the effect of a disruptive pattern is to break up what is really a continuous surface into what appears to be a number of discontinuous surfaces... which contradict the shape of the body on which they are superimposed. —Hugh Cott