Cover of first edition
Hugh Bamford Cott|
Introduction by Julian Huxley
|Illustrator||Hugh Bamford Cott|
|Publisher||Methuen, Oxford University Press|
Adaptive Coloration in Animals is a 500-page textbook about camouflage, warning coloration and mimicry by the Cambridge zoologist Hugh Cott, first published during the Second World War in 1940; the book sold widely and made him famous.
The book's general method is to present a wide range of examples from across the animal kingdom of each type of coloration, including marine invertebrates and fishes as well as terrestrial insects, amphibians, reptiles, birds and mammals. The examples are supported by a large number of Cott's own drawings, diagrams, and photographs. This essentially descriptive natural history treatment is supplemented with accounts of experiments by Cott and others. The book had few precedents, but to some extent follows (and criticises) Abbott Handerson Thayer's 1909 Concealing-Coloration in the Animal Kingdom.
The book is divided into three parts: concealment, advertisement, and disguise. Part 1, concealment, covers the methods of camouflage, which are colour resemblance, countershading, disruptive coloration, and shadow elimination. The effectiveness of these, arguments for and against them, and experimental evidence, are described. Part 2, advertisement, covers the methods of becoming conspicuous, especially for warning displays in aposematic animals. Examples are chosen from mammals, insects, reptiles and marine animals, and empirical evidence from feeding experiments with toads is presented. Part 3, disguise, covers methods of mimicry that provide camouflage, as when animals resemble leaves or twigs, and markings and displays that help to deflect attack or to deceive predators with deimatic displays. Both Batesian mimicry and Müllerian mimicry are treated as adaptive resemblance, much like camouflage, while a chapter is devoted to the mimicry and behaviour of the cuckoo. The concluding chapter admits that the book's force is cumulative, consisting of many small steps of reasoning, and being a wartime book, compares animal to military camouflage.
Cott's textbook was at once well received, being admired both by zoologists and naturalists and among allied soldiers. Many officers carried a copy of the book with them in the field. Since the war it has formed the basis for experimental investigation of camouflage, while its breadth of coverage and accuracy have ensured that it remains frequently cited in scientific papers.
Adaptive Coloration in Animals is a 500-page book, 10 by 7 inches (250 by 180 mm) in its first edition. It was published by Methuen (in London) and Oxford University Press (in New York) in 1940. It is full of detailed observations of types of camouflage and other uses of colour in animals, and illustrated by the author with clear drawings and photographs. There is a coloured frontispiece showing eight of Cott's paintings of tropical amphibians. The book has 48 monotone plates and several illustrations.[P 1]
Cott's method is to provide a large number of examples, illustrated with his own drawings or photographs, showing animals from different groups including fish, reptiles, birds and insects, especially butterflies. The examples are chosen to illustrate specific adaptations. For example, the fish Chaetodon capistratus is described as follows:[P 2]
this species had the habit of swimming very slowly tail first: but when disturbed it darts rapidly off to safety in the opposite direction... C. capistratus adopts the same tactics... [This fish] is of particular interest in that the real eye is obliterated and a false eye substituted in one and the same animal.-- Hugh Cott[P 2]
Cott was well aware that he was publishing in wartime. There are, as Julian Huxley remarks in his 'Introduction', references throughout the book to the human analogues of animal camouflage and concealment. For example, in the section on 'Adaptive Silence', the kestrel is said to "practise dive-bombing attacks", or "after the fashion of a fighter 'plane" to fly down other birds, while "Owls have solved the problem of the silent air-raid"; Cott spends the rest of that paragraph on the "method which has recently been rediscovered and put into practice" of shutting off a bomber's engines and "gliding noiselessly down towards their victims" at Barcelona in the Spanish Civil War.[P 3] In the concluding chapter, Cott explicitly states "The innumerable visible devices used .. in peace-time and in war-time .. are merely rediscovered .. applications of colour that have already reached a high .. degree of specialization and perfection .. in the animal world", mentioning predator-prey relationships, sexual selection and signalling to rivals. He then compares the "hunting disguises put on .. as a means of approaching, ambushing or alluring game, and the sniping suits, concealed machine-gun posts, and booby traps" with the camouflage of animal predators; and similarly he compares "protective disguises" with the "photographer's hide and the gunner's observation post." In the same section, Cott compares intentionally visible signs with animal warning colours: "The policeman's white gloves have their parallel in the white stripes or spots of nocturnal skunks and carabids. The Automobile Association has adopted a system of coloration [black and yellow] whose copyright belongs by priority to wasps and salamanders."[P 4]
The book addresses its subject under three main headings: concealment, advertisement, and disguise.
Cott sets out his view that we have to be re-taught how to see, mentioning Ruskin's "innocence of the eye". He argues that camouflage should, and in animals actually does, use four mechanisms: colour resemblance, obliterative shading (i.e. countershading, the graded shading which conceals self-shadowing of the lower body), disruptive coloration, and shadow elimination.
Chapter 1. General colour resemblance.
Chapter 2. Variable colour resemblance. Caterpillars and pupae (as in Poulton's famous experiment) are coloured to match their environment. Mountain hares change colour in winter; many fish, cephalopods, frogs, and crustacea can change colour rapidly.
Chapter 3. Obliterative shading.
Chapter 4. Disruptive coloration.
The simplified diagrams in Fig. 7 illustrate the value and effectiveness of maximum disruptive contrasts better than any verbal description... On looking at these drawings from a little distance, it will be seen that the conspicuous patches operate most efficiently in distracting attention from the form of the animals wearing them. By sheer force of their brightness, or blackness, or contrasts, they dominate the picture presented to the eye, apparently destroying their form...[P 5]
Cott goes on to explain that the right-hand drawing shows the effect "of broken surroundings in further blending and confusing the picture",[P 5] observing that this is the closest to what is seen in nature. His readers are invited to look first at the right-hand images to gain an idea of the power of "these optical devices" as camouflage, putting off the moment when the animal is actually recognised.[P 6]
Chapter 5. Coincident disruptive coloration.
Chapter 6. Concealment Of the shadow.
Chapter 7. Concealment in defence, mainly as illustrated by birds.
Chapter 8. Concealment In offence.
Chapter 9. Objections and evidence bearing on the theory of concealing coloration.
Chapter 10. The effectiveness of concealing coloration.
Chapter 1. The appearance and behaviour of aposematic animals.
Chapter 2. Warning displays.
Chapter 3. Adventitious warning coloration.
Chapter 4. The nature and function of warning coloration, as illustrated by the mammalia.
Chapter 5. The Protective Attributes Of Aposematic Animals In General.
Chapter 6. The relation between warning colours and distasteful attributes.
Chapter 7. The effectiveness of protective attributes associated with warning colours.
Chapter 8. Experimental evidence that vertebrate enemies learn by experience.
Chapter 9. Evidence of selective feeding by vertebrate enemies in a state of nature.
Chapter 1. Special resemblance to particular objects.
Chapter 2. Adaptive behaviour in relation to special cryptic resemblance.
This wonderful bird...habitually selects the top of an upright stump as a receptacle for its egg, which usually occupies a small hollow just, and only just, large enough to contain it. ... the stump selected had thrown up a new leader just below the point of fracture; ... the bird sat facing this in such a way that when viewed from behind they came into line and blended with the grey stem.[P 8]
Chapter 3. Adventitious Concealing Coloration.
Chapter 4. Deflective marks.
Chapter 5. Directive marks.
Chapter 6. Alluring coloration.
Chapter 7. Mimicry: the attributes of mimics.
Chapter 8. Breeding parasitism and mimicry in cuckoos.
The final chapter confirms that "The force of the facts and arguments used in this work is cumulative in effect." Many small steps of reasoning combine to show that "adaptive coloration ... has been ... one of the main achievements of organic evolution." The book ends by comparing human artefacts and "natural adaptations", both of which can have goals (recall the publication date of 1940, early in the Second World War) including "the frustration of a predatory animal or of an aggressive Power".
Julian S. Huxley wrote a foreword (labelled 'Introduction') which defends the Darwinian concept of adaptation, especially of colour (in animals) and within that frame of mimicry. He makes it clear that "in these last thirty years" (that is, from about 1910 to 1940) he believed that "experimental biologists" professed, even if they did not actually hold, "a radical scepticism on the subject of adaptations", in other words about whether natural selection really could have created the enormous diversity of pattern and colour seen in nature.[P 12] Huxley quoted the now long-forgotten Aaron Franklin Shull's 1936 Evolution which stated "These special forms [sexual selection, warning colours, mimicry and signalling] of the selection idea ... seem destined to be dropped, or at least relegated to very minor places in the Evolution discussion.", and more sharply that "aggressive and alluring resemblance" (Huxley's words) "must probably be set down as products of fancy belonging to uncritical times." Huxley's reply is simply[P 12]
Dr. Cott, in this important book, has turned the tables with a vengeance on objectors of this type... Had they taken the trouble to acquaint themselves with even a fraction of the relevant facts to be found in nature, they could never have ventured to enunciate such sweeping criticisms: their objections are a measure of their ignorance.-- Julian Huxley[P 12]
With objections dismissed, Huxley remarks that "Dr. Cott is a true follower of Darwin in driving his conclusions home by sheer weight of example," observing that "Faced with his long lists of demonstrative cases, the reader is tempted to wonder why adaptive theories of coloration have been singled out for attack by anti-selectionists." Huxley also noted Cott's "constant cross-reference to human affairs", and that it was good to know that Cott was applying his principles "to the practice of camouflage in war".[P 12]
Huxley concluded his introduction by describing Adaptive Coloration as "in many respects the last word on the subject", upholding the great tradition of "scientific natural history".[P 12]
Reviewers had little to compare Adaptive Coloration with. The English zoologist Edward Bagnall Poulton, a Darwinian, had written a 360-page book, The Colours of Animals, fifty years earlier in 1890, and he was able, at age 84, to review Cott's work in Nature on its appearance in 1940, beginning with the words
This excellent work, eagerly awaited for many years, will be most welcome to naturalists, even, we may hope, to the few who have hitherto rejected the Darwinian interpretation which the author has here supported by a mass of additional evidence based on his own observations and those of very many others.-- E.B. Poulton
In this Neodarwinian epic Dr. Cott stamps himself as a true disciple of the master evolutionist. Indeed, he rivals Darwin in the thorough, objective and penetrating analysis of a major biological problem. An immense body of facts and interpretation, much of it original, has been judiciously considered and brought to bear on the question of the biological significance of coloration.-- Carl L. Hubbs
Hubbs notes that Cott is seeming concerned about the scarcity of experimental data for the survival value of camouflage, and accordingly relies on Sumner and Isely's "clear-cut results", but at once continues that Cott relies on "the general lore of natural history". Hubbs also remarks on the "resurgence to Darwinian views", referring to the scepticism about the power of natural selection among both geneticists of the time and to the Lamarckist views of Trofim Lysenko.
Hubbs observes that Cott is both an artist and a naturalist as well as a scientist: "In section after section, rivaling one another in fascination, this master of art and of natural history unfolds the biological significance of adaptive coloration in animals." And Cott's emphasis on disruptive patterning and (following Thayer) countershading clearly affected the reviewer: "Particularly impressive is the author's treatment of "coincident disruptive coloration", in which a ruptive mark crosses structural boundaries, so as to obliterate visually such ordinarily conspicuous parts as the eye and the limbs. Concealment of an animal's ordinarily telltale shadow is also stressed". Hubbs's review ends "This book is the work of an artist, and it is a work of art. Every biologist with an interest in any phase of natural history or evolution should keep it at hand."
"W.L.S.", reviewing Cott in The Geographical Journal in 1940, begins with "In this large and well-illustrated volume the author discusses at length reason or reasons for the various colour patterns found in the animal kingdom." The reviewer goes on "He has presented us with a vast number of facts and observations which are somewhat difficult to analyse." However "W.L.S." admits that disruptive coloration "is discussed at considerable length by Mr. Cott and many remarkable instances of it are considered in detail". The review ends by mentioning that while biologists (of the 1930s) usually "reject the influence of Natural Selection in evolution, the facts of adaptive coloration as given in Mr. Cott's work are a strong argument in its favour, and must be given due weight. This is what Mr. Cott claims to have accomplished in a volume which will certainly take its place as a most valuable contribution to zoological literature."
Peter Forbes, in his book Dazzled and Deceived, wrote that
Cott's Adaptive Coloration in Animals must be the only compendious zoology tract ever to be packed in a soldier's kitbag. The book also marks the apotheosis of the descriptive natural history phase of mimicry studies. Although Cott does report experiments on predation to test the efficacy of mimicry and camouflage, the book is essentially a narrative of examples plus theory.
Over 60 years after its publication, Adaptive Coloration in Animals remains a core reference on the subject. Sören Nylin and colleagues observe in a 2001 paper that
Adaptive coloration in animals has been a very active research field in evolutionary biology over the years (e.g. Poulton 1890, Cott 1940, Kettlewell 1973, Sillen-Tullberg 1988, Malcolm 1990), and one in which the Lepidoptera have always featured prominently as model species.-- Sören Nylin
As a natural history narrative on what has become an intensely researched experimental subject,Adaptive Coloration could be thought obsolete, but instead, Peter Forbes observes "But Cott's book is still valuable today for its enormous range, for its passionate exposition of the theories of mimicry and camouflage". This width of coverage and continuing relevance can be seen in the introduction to Sami Merilaita and Johan Lind's 2005 paper on camouflage, Background-Matching and Disruptive Coloration, and the Evolution of Cryptic Coloration, which cites Adaptive Coloration no fewer than eight times, quoting his terms "cryptic coloration or camouflage", "concealing coloration", "background matching (also called cryptic resemblance)", "disruptive coloration", resemblance to visual background, and the difficulty a predator has to detect a prey visually.
The zoologist Hugh Cott had the final word in Adaptive Coloration in Animals (1940), a definitive synthesis of everything known about camouflage and mimicry in nature. Cott ruffled fewer feathers [than Trofim Lysenko or Vladimir Nabokov], and his well-organized and unfanatic ideas proved militarily effective, even under the scrutiny of improved techniques for target detection. Thayer's principles reemerged in more temperate and rational terms, and camouflage schemes based on them survived both photometric analyses and enemy encounters. Biomimetic camouflage took its place as yet another technique in a sophisticated armamentarium of visual deceptions.
Camouflage researcher Roy Behrens cites and discusses Adaptive Coloration frequently in his writings. For example, in his Camoupedia blog, related to the book of the same name, he writes of Cott's drawings of the hind limbs of the Common frog: "Reproduced above is one of my favorite drawings from what is one of my favorite books." He continues "What makes these drawings (and the book itself) even more interesting is that Cott (1900-1987) was not just a zoologist--he was a highly skilled scientific illustrator (these are his own pen-and-ink drawings), a wildlife photographer, and a prominent British camoufleur in World War II." Still in 2011, Behrens can write of Cott's way of thinking, citing his words as models of clear and accurate explanation of the mechanisms of camouflage: "As he so aptly explained it, disruptive patterns work 'by the optical destruction of what is present', while continuous patterns work 'by the optical construction of what is not present.'"
Adaptive Coloration in Animals has been published as follows: