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Dazzled and Deceived

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1 2 3 4 5 DAZZLED AND DECEIVED 6 7 AND 8 9 10 PETER FORBES 1 2 3 4 5 6 7 8 9 20 1 2 3 4 5 6 7 8 9 30 1 2 3 4 YALE UNIVERSITY PRESS 5 NEW HAVEN AND LONDON 36R 2956_Pre.qxp 8/28/09 8:49 PM Page vii

1 2 3 4 5 CONTENTS 6 7 8 9 10 List of Illustrations ix 1 Acknowledgements xii 2 Prologue 1 3 4 5 CHAPTER 1 Darwinians, mockers and mimics 6 6 CHAPTER 2 Swallowtails and Amazon 31 7 CHAPTER 3 Delight in 43 8 CHAPTER 4 Pangenesis 57 9 CHAPTER 5 On the wings of angels 71 20 CHAPTER 6 Dazzle in the dock: The First World War 85 1 CHAPTER 7 Camouflage and cubism in the First World War 101 2 CHAPTER 8 Hopeful monsters? 113 3 CHAPTER 9 The natural history of the visual pun 127 4 CHAPTER 10 Cannibals and Sunshields 138 5 CHAPTER 11 Dazzle (revisited) to D-Day 170 6 CHAPTER 12 From to babies and back 182 7 CHAPTER 13 The aromas of mimicry 197 8 CHAPTER 14 The tinkerer’s palette 207 9 CHAPTER 15 The variations 221 30 CHAPTER 16 A shifting spectrum 235 Epilogue 250 1 2 Notes 256 3 Bibliography 273 4 Index 277 5 36R 2956_Prologue.qxp 8/28/09 8:50 PM Page 1

1 2 3 4 5 6 7 PROLOGUE 8 9 10 1 2 3 As I write, a comma has just flown into the house, intending to 4 hibernate. It sits motionless in the window, with its wings closed. Because 5 it has to survive the winter without moving, it is a brilliant mimic: the 6 wings are scalloped ornately as if the margins had been nibbled, totally 7 disrupting the typical butterfly wing pattern. of mottled grey to 8 brown spread across the wing, just like the patterns on a dead leaf, and 9 there is a tiny crescent shape in white on each wing, like a fleck of bird’s 20 droppings. It is a tattered leaf, which can lie unnoticed throughout the 1 winter. 2 The beauty and purpose of the comma’s leaf mimicry are obvious. 3 Since vision first developed in creatures in the Cambrian era, around 540 4 million years ago, appearances have been hugely significant in shaping the 5 course of . The art historian Sir Ernst Gombrich (1909–2001) 6 was interested in more than paintings: he took the whole field of visual 7 representation as his province and he wrote beautifully on mimicry and 8 what ’s copying and stylised warnings mean for the art of 9 beings: ‘For the evolution of convincing images was indeed anticipated by 30 nature long before human minds could conceive this trick . . . the art 1 historian and the critic could do worse than ponder these miracles. They 2 will make him pause before he pronounces too glibly on the relativity of 3 standards that make for likeness and recognition.’ 4 Gombrich finds various styles of art in nature: a leaf butterfly can fanci- 5 fully be considered to be ‘a naturalistic artist’, having 36R 2956_Prologue.qxp 8/28/09 8:50 PM Page 2

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1 produced a facsimile of the dead-leaf pattern. But the eyespots sported by 2 some butterflies are stylised gestures: ‘They represent, if you like, the 3 Expressionist style of nature.’ Then there are patterns whose meaning is 4 established by association. Creatures which are protected by toxicity or 5 powerful defences such as stings signal their danger with bright warning 6 colours: in temperate regions, and ladybirds are typical examples. 7 The warning colours of toxic – red, yellow, black and white – are 8 also the colours we use for our road signs and for hazardous materials 9 logos. This may be an innate response of living creatures to bright colours, 10 which stand out against the duller greens, browns and greys of vegetation 1 and rock. Perhaps the colours have become associated with danger over 2 long periods of evolutionary time, and so have only a conventional 3 meaning, in the same way in which the names of objects are assigned by 4 convention (a road is not intrinsically a ‘road’, but also a ‘rue’, an ‘ulitsa’ 5 or thousands of other names in different languages). At any rate, the 6 parallels between natural and human warning coloration are too obvious 7 to ignore. 8 Deception has always played a large role in human affairs. Early 9 – hunter gatherers – were as adept in the wiles of camouflage as 20 any : they had to be.* The biblical story of Esau and Jacob has an 1 uncannily biological feel to it. When the ‘smooth man’ Jacob wanted to 2 impersonate the ‘hairy man’, his hunter brother Esau, in front of their 3 blind and aged father Isaac, he covered himself with hairy goatskins. Isaac 4 recognised Jacob’s voice but preferred to trust in the smell and hairy feel 5 of the goat hunter – smell and touch being more primal and elemental 6 than hearing: ‘The voice is the voice of Jacob, but the hands are the 7 hands of Esau.’ 8 Ambiguity and disguise exert a powerful hold on the human imagina- 9 tion. Mistaken identity, whether intentional or accidental, has permeated 30 1

2 * Strictly, the word ‘camouflage’ did not exist before it was coined by the French in 1917, during 3 the First World War. The word derives from the verb camoufler: to dress up, disguise. Before its 4 use in war, it had theatrical connotations and the terms ‘concealing coloration’ or ‘protective coloration’ were used instead. ‘Camouflage’ is so much the better word that I use it throughout, 5 even when it is technically anachronistic. ‘Protective coloration’ can also mean, not concealment, 36R but display. 2956_Prologue.qxp 8/28/09 8:50 PM Page 3

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myths, legends and literature. In particular, in the Oedipus legend or 1 in many of Shakespeare’s plots – As You Like It, The Merchant of Venice, 2 Measure for Measure, A Midsummer Night’s Dream, Twelfth Night, The 3 Winter’s Tale – falsifying a person’s identity is the engine of many human 4 dramas. In human society now, these doubts are put to the court of DNA 5 testing; and in the realm of nature DNA reveals that many species are not 6 what they appear to be on the surface. 7 Most in the human realm have a parallel in nature: when 8 the Trojans led the Horse into their city, unsuspecting that it was packed 9 with Greek soldiers, they were at one with the who, fooled by decep- 10 tive chemical odours, carry of some blue butterflies into their 1 nest and feed them in preference to their own larvae. The passage in 2 Macbeth in which the men of Malcolm’s army disguise themselves as 3 trees in their approach to Dunsinane prefigures the modern sniper, 4 decked out in tattered rags, twigs and . 5 Until the end of the nineteenth century, troops wore intimidatory, 6 bright uniforms, red being a favourite – as it is among the many toxic 7 species which proclaim their dangerousness by conspicuous display. But 8 in the later years of the nineteenth century the increased power of 9 weaponry, especially the machine gun, made concealment a priority. 20 Camouflage in war has been a test case of the ‘two cultures’. In normal 1 times, attempts to find links between art and science are well meaning 2 but mostly of no avail, because the territories and methods of their disci- 3 plines seem so different. But in camouflage in wartime, both biologists 4 and artists felt they had unique expertise to offer. Now the territory was 5 the same, but the mindsets were very different. The story of the attempt 6 to apply lessons from nature’s camouflage and mimicry to military 7 combat in the two world wars has many intriguing twists, involving three 8 principal naturalists – Sir John Graham Kerr, Hugh Cott and Sir Peter 9 Scott – besides a cast of artists, soldiers and one magician. The conver- 30 gence of nature, art and science in the world wars occupies the central 1 period covered here: between the explorations of the pioneers and the 2 hi-tech genetic work of today. As a recent themed issue of the Royal 3 Society’s Transactions recognises: ‘Camouflage research has for a signifi- 4 cant length of time linked , art and the military, stemming from 5 the work and influence of Abbott Thayer and Hugh Cott.’ 36R 2956_Prologue.qxp 8/28/09 8:50 PM Page 4

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1 The artistic aspect of mimicry and camouflage lends an added dimen- 2 sion to the allure of the subject. I began to collect examples of mimicry 3 twenty-five years before beginning this book, at a time when I was 4 working as a natural history desk editor. At that stage I saw mimicry 5 primarily in terms of descriptive natural history, with strong aesthetic 6 overtones. The stories in Hugh Cott’s Adaptive Coloration in 7 (1940), which was at the time still the most compendious and authorita- 8 tive text on the subject, enthralled me with their revelations of surprising 9 mimicry in exotic settings. 10 But mimicry is more than a fantastical tale of visual punning in nature: 1 it can tell us so much about evolution. The story of evolution is the biggest 2 prize in biology. To understand how living things develop from the egg; 3 how the genes act to shape the organs; to know in depth how inheritance 4 works; to unravel the genetic basis of disease and to devise cures: these 5 are the normal goals of most biological research. But the more we know 6 about organic processes in the here and now, the more we learn about the 7 three-and-a-half-billion-year journey from the first replicating molecules 8 to the current, multi-million species cornucopia of life. One of the most 9 startling findings of molecular biology has been the revelation that all 20 creatures are closer cousins under the skin than we had imagined. The 1 question ‘Are you a man or a mouse?’ can now be answered ‘Both’ – since 2 around 99 per cent of human genes have a mouse equivalent. It seems 3 that large differences in the form and of animals have been 4 achieved by relatively minor genetic . 5 But evolution did not occur only by shuffling a pack of genetic cards. 6 Whether genes can be passed on at all depends on how an organism lives 7 in a real environment with other creatures. Understanding how genes 8 and the total environment interact over vast stretches of time is an enor- 9 mously complicated issue and we don’t have video footage of the past, 30 but to look at the evolution of a restricted phenomenon can be a test 1 case. Mimicry and camouflage – the resemblance that one life-form has 2 either to another or to a part of the environment – have some special 3 features which make them for studying evolution in action. And the 4 best subjects are – , , but above all butterflies and 5 moths. There are many reasons for this. The rapid turnover of genera- 36R tions in insects and their vulnerability mean that natural selection bears 2956_Prologue.qxp 8/28/09 8:50 PM Page 5

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very heavily on them. And butterflies are special among insects because 1 their whole being is displayed on their wings – two-dimensional objects 2 are easier to study than anything with three. 3 Very often we fall into circular arguments when we speculate on 4 evolution because there is no purpose to it – no end in sight. We see that 5 some organisms have survived, so we say that these must have been the 6 fittest. And which are ‘the fittest?’ Those which have survived. But in 7 mimicry one creature has led and another has, through selection, copied 8 it. The old problem of attributing to nature a goal when it has none 9 dissolves in the face of mimicry because, although there is no purpose to 10 the whole of it, for the mimicking species there is a goal: to copy the 1 model. So we have an index of the success of evolution in producing the 2 match. Similarly with the butterflies that mimic dead leaves. Success is 3 demonstrable. 4 So, if we discovered the pattern-forming genes in a mimic and its 5 related but non-mimetic cousins, we would learn something about adap- 6 tation, natural selection and the genetic mechanisms behind a particular 7 instance of precise copying. Obviously camouflage is somewhat different, 8 but no less intriguing. When a moth exquisitely disappears against the 9 bark of a tree, it tells us something about the passive I-am-a-camera nature 20 of the genetic pattern-forming processes; but there will be no correlation 1 between the genes which make the bark in a tree and the genes which 2 make the patterns on the moth’s wings. In mimicry, we will see how some 3 quite similar pattern-making genetic machinery has been tweaked in one 4 butterfly to match another. 5 As the genes behind mimetic resemblances and the time scale on 6 which mimicry was achieved are revealed, the course of evolution will be 7 reconstructed. Evolution leaves traces of its innovations in the DNA of 8 present-day organisms: not a simple record that we can read as a timeline 9 of development, but rather as forensic clues to be matched against fossil 30 evidence. The story of evolution will probably be revealed first in 1 mimetic and camouflaged creatures. I cannot think of a more enticing 2 project, involving beautiful creatures in luxuriantly populated environ- 3 ments and the shifts in DNA which lie behind them. 4 5 36R

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