tag:theconversation.com,2011:/fr/topics/blue-22555/articlesBlue – The Conversation2023-07-04T15:11:39Ztag:theconversation.com,2011:article/2086392023-07-04T15:11:39Z2023-07-04T15:11:39ZBiting flies are attracted to blue traps – we used AI to work out why<p>Flies which feast on blood – such as tsetse and horse flies – inflict painful bites and spread debilitating diseases among people and animals alike. So a lot of work has gone into designing the most efficient traps to control the populations of these flies.</p>
<p>Biting fly traps tend to be blue, because decades of field research has shown that such flies find this colour especially attractive. But it’s never been clear why these flies find blue to be so irresistible – especially since blue objects are not a common sight in the natural environment.</p>
<p>Scientists have speculated that blue surfaces might look like <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2003.0121">shaded places</a> to flies since shadows have a blueish tinge. Tsetse flies in particular seek out such shaded spots to rest in, which might explain their attraction to blue traps. </p>
<p>Another possibility is that blue surfaces might <a href="https://resjournals.onlinelibrary.wiley.com/doi/full/10.1046/j.1365-2915.1999.00163.x">lure hungry flies</a> by providing them with the telltale signs they use to distinguish animals against a background of foliage. According to this theory, a fly might mistake a blue trap for an animal it wishes to bite and feed upon. </p>
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<img alt="A blue canvas, diamond shaped container is suspended from a tree." src="https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A bright blue trap for tsetse flies is suspended from a tree.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bright-blue-trap-dangerous-tsetse-fly-724357057">Fabian Plock/Shutterstock</a></span>
</figcaption>
</figure>
<p>But assessing these possibilities is especially tricky because flies perceive colour differently to people. Humans perceive colour using the responses of three kinds of light-detecting photoreceptor in the retina which are broadly sensitive to blue, green and red wavelengths of light.</p>
<p>But most “higher flies” – such as tsetse and horseflies – have five kinds of photoreceptor sensitive to UV, blue and green wavelengths. So, a blue trap won’t look the same to a fly as it does to the human who designed it.</p>
<h2>From flies to AI…</h2>
<p>In <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2023.0463#d1e1574">our study</a>, we tackled the problem by using artificial intelligence (AI). We used artificial neural networks which are a form of machine learning inspired by the structure of real nervous systems. Artificial neural networks learn by modifying the strengths of connections between a network of artificial neurons.</p>
<p>We fed these networks with the photoreceptor signals that a fly would experience when looking at animals or foliage backgrounds, both in light and in shade. We then trained the networks to distinguish animals from leaves, and shaded from unshaded objects, using only that visual information.</p>
<p>The trained networks would find the most efficient way of processing the visual signals, which we expected to share properties with the mechanisms that have evolved in real flies’ nervous systems. We then investigated whether the artificial neural networks classified blue traps as animals or as shaded surfaces.</p>
<h2>Blueness or brightness?</h2>
<p>After training, our neural networks could easily distinguish animals from leaf backgrounds, and shaded from unshaded stimuli, using the sensory information available to a fly. However, what surprised us was that they solved these problems in completely different ways.</p>
<p>The networks identified shade using brightness and not colour – quite simply, the darker a stimulus appeared, the more likely it was to be classified as shaded. Meanwhile, animals were identified using the relative strength of blue and green photoreceptor signals. Relatively greater blue compared to green signals indicated that a stimulus was probably an animal rather than a leaf, and vice versa.</p>
<p>The implications of this became clear when we fed these networks the visual signals caused by blue traps. The blue traps were never mistaken for shaded surfaces, but they were commonly misclassified as animals.</p>
<figure class="align-center ">
<img alt="A close up of an insect with huge blue/green eyes" src="https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The horse fly (<em>Hybomitra epistates</em>) can inflict painful bites upon people and livestock.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/horse-fly-hybomitra-epistates-portrait-1773555527">Mircea Costina/Shutterstock</a></span>
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<p>Of course, artificial neural networks are not real flies, nor exact models of a fly’s nervous system. But they do show us the most efficient way of processing a fly’s visual signals to identify natural stimuli. And we expect evolution to have taken advantage of similar principles in real fly nervous systems.</p>
<p>The best way to identify shade using the visual information a fly has is through brightness and not blueness. Meanwhile, the best way of identifying animals was, somewhat counterintuitively, using blueness. Such a mechanism is very strongly stimulated by blue traps, explaining why they prove such a powerful lure for hungry flies. Further evidence for this idea comes from field studies which show that tsetse landing on coloured traps are <a href="https://resjournals.onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3032.1990.tb00519.x">relatively starved</a>.</p>
<p>If we can understand the sensory signals and behaviour that cause flies to be caught in traps, we can engineer traps to more efficiently exploit those mechanisms and more effectively control the flies. We’ve already had <a href="https://journals.plos.org/plosntds/article?id=10.1371%2Fjournal.pntd.0007905#:%7E:text=Tsetse%20can%20be%20controlled%20using%20insecticide-treated%20fabric%20targets%2C,these%20fabrics%20to%20be%20more%20attractive%20to%20tsetse.">some success</a> in doing this for tsetse flies.</p>
<p>More effective traps will help minimise the impacts of those flies on health and welfare of people and animals. They could help prevent the damaging effects of biting flies on livestock, help in the fight against dangerous fly-borne diseases such as <a href="https://www.who.int/news-room/fact-sheets/detail/trypanosomiasis-human-african-(sleeping-sickness)">sleeping sickness</a>, and protect us and animals from fly attacks in general.</p><img src="https://counter.theconversation.com/content/208639/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Santer has received funding from the Knowledge Economy Skills Scholarships program, and from the Centre for International Development Research at Aberystwyth (CIDRA). </span></em></p>New research on what attracts blood-feasting flies to blue objects could help minimise the impacts of those insects on people and animals.Roger Santer, Lecturer in Zoology, Aberystwyth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1759562022-02-01T12:21:10Z2022-02-01T12:21:10ZUlysses at 100: why Joyce was so obsessed with the perfect blue cover<figure><img src="https://images.theconversation.com/files/443450/original/file-20220131-118143-cljnde.jpg?ixlib=rb-1.1.0&rect=7%2C7%2C2620%2C1788&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">James Joyce was particular about the shade of blue that would grace the cover of Ulysses.</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Ulysses_(novel)#/media/File:James_Joyce_Ulysses_1st_Edition_1922_GB.jpg">Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>On February 2 2022, Ulysses turns 100, James Joyce would have turned 140, and I will turn 30-something.</p>
<p>To celebrate this tripartite birthday I am popping to the chemist to collect some eye drops. Then I’m heading to the Bodleian Library in Oxford to view one of the first editions of Ulysses. I won’t read it. I won’t even venture past its covers. I am interested in seeing the exact shade of blue that Joyce specified for the book’s wrappers. He was so particular about this aesthetic feature that he got his painter friend, <a href="https://www.annexgalleries.com/artists/biography/3862/Nutting/Myron">Myron Nutting</a>, to mix up the precise tint.</p>
<p>This is where the eye drops come in. I have a chronic condition that can make my eyes sore and my vision blurry. And I want to ensure that I can see Ulysses clearly, to properly assess the blueness of its cover. The irony is that Joyce’s eyesight was far worse than mine. He experienced severe eye pain, underwent multiple ocular surgeries and, at times, could barely see at all. Why, then, was he so obsessed with his book being such a specific hue of blue?</p>
<h2>Ulysses Blue</h2>
<p>Joyce’s biographer, Richard Ellmann, tells us that the cover of Ulysses was meant to match the blue of the Greek flag, to suggest <a href="https://archive.org/details/jamesjoyce00rich/page/524/mode/2up?q=nutting">the myth of ancient Greece and Homer</a>. We know from his letters that Joyce sent a Greek flag to Nutting for him to colour-match. So, he was aiming for “Greek” blue. </p>
<p>We also know that Homer was a huge influence on Joyce. <a href="https://culturedarm.com/homeric-parallel-ulysses-joyce-nabokov-homer-maps/">The structure of Ulysses parallels the structure of Homer’s Odyssey</a>. So, it makes sense for Joyce to honour his literary hero through a subtle, yet exceedingly specific, decorative detail. But I think there’s more to it. </p>
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<img alt="Statues of Homer against a gloomy sky." src="https://images.theconversation.com/files/443446/original/file-20220131-13-14aztav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443446/original/file-20220131-13-14aztav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443446/original/file-20220131-13-14aztav.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443446/original/file-20220131-13-14aztav.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443446/original/file-20220131-13-14aztav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443446/original/file-20220131-13-14aztav.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443446/original/file-20220131-13-14aztav.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Homer was a great inspiration to James Joyce.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/statue-homer-university-virginia-709661524">Timothy Harding/Shutterstock</a></span>
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<p>I am on a research odyssey to discover the impetus and symbolism behind “Ulysses blue”. I will go to the Bodleian with my eyes wide open, ready to let my visual experience of the famous blue book dictate my avenue of research.</p>
<p>But, given Joyce’s impaired vision, perhaps this isn’t the best approach. To understand Joyce’s perspective, I must shrug off my “<a href="http://artandpopularculture.com/Ocularcentrism">ocularcentrism</a>”.</p>
<h2>Blindness in Joyce’s texts</h2>
<p>In her thoughtful new book, <a href="https://www.penguinrandomhouse.com/books/611683/there-plant-eyes-by-m-leona-godin/">There Plant Eyes: A Personal and Cultural History of Blindness</a>, writer and educator M. Leona Godin devotes several pages to her interactions with Ulysses. She discusses the “<a href="https://drmlgodin.com/2019/10/tap-tap-tap-joyces-blind-stripling-in-honor-of-white-cane-safety-day/">blind stripling</a>” character who taps his way through Dublin, and through Ulysses, using his “slender cane”. </p>
<p>Godin praises Joyce’s ability to capture the musicality of the tapping cane and articulates the complexity of Joyce’s relationship with blindness: “Even if Joyce felt some kinship with the blind stripling, he was still a sight-oriented person who might think […] of the blind as ‘they’.”</p>
<p>Joyce would have loved Godin’s book, as he appears to have had a keen interest in blindness memoirs and advice guides written by blind people, for blind people (and their supporters). Scholars have largely glossed over Joyce’s references to blindness in his <a href="https://catalogue.nli.ie/Record/vtls000357760/HierarchyTree#page/1/mode/1up">composition notebook</a>. But I’m delving deeper to get to grips with Joyce’s thoughts on visual impairment. </p>
<p>It is fascinating to read Joyce’s depiction of the blind stripling in Ulysses, alongside one of the blindness books mentioned in his notes: <a href="https://archive.org/details/lesaveuglesparun00maur/page/n7/mode/2up"><em>Les Aveugles par un Aveugle</em> (The Blind as Seen through Blind Eyes)</a> (1899), by Maurice de la Sizeranne. </p>
<p>As I outlined in a <a href="https://www.youtube.com/watch?v=HB8pOCFEp5w">public lecture</a> last Bloomsday, there are several similarities, in terms of content and focus, between the two books. </p>
<p>The observations de la Sizeranne makes about his fellow blind man parallel those made by Ulysses’ protagonist Bloom about the blind stripling. Both Bloom and de la Sizeranne discuss the intriguing relationship between colour perception and touch, in blind experience, and suggest an additional blind sense: a “kind of sense of volume” involving the “nerves of the face” or the “forehead”. In reflecting blind experience onto his blind readers, de la Sizeranne - to borrow a phrase used in Ulysses - urges us to “see ourselves as others see us”.</p>
<p>In Joyce’s notes, the name of a hitherto unidentified “Dr Staub” is scrawled next to the title of de la Sizeranne’s book. Staub was believed to be one of Joyce’s eye doctors. However, I have discovered that he is, in fact, <a href="https://www.sbs.ch/ueber-uns/portraet/geschichte/">Dr Theodor Staub</a>, the blind founder of the Swiss Library for the Blind. </p>
<p>It is unclear why Staub’s name appears next to <em>Les Aveugles par un Aveugle</em>. Whatever the precise connection, in jotting down Staub’s name Joyce, at the very least, demonstrated a desire to engage with the blind community and with books for the blind.</p>
<h2>Blind, blue bards</h2>
<p>In his final book, Finnegans Wake (1939), Joyce alludes to Ulysses. He depicts Shem, a partially sighted writer, reading a “usylessly unreadable Blue Book” in a “glaucous den”. </p>
<p>In ancient Greek, the word “glaucous” refers to blueish-green or blueish-grey. It’s also the root word of “<a href="https://www.dovepress.com/the-early-history-of-glaucoma-the-glaucous-eyenbsp800-bc-to-1050-ad-peer-reviewed-fulltext-article-OPTH">glaucoma</a>”. Joyce suffered from glaucoma, and, in one of his letters, he writes that Homer “went blind from glaucoma according to one of my doctors”.</p>
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<img alt="Blue cover of Ulysses." src="https://images.theconversation.com/files/443257/original/file-20220129-25-13a0oil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/443257/original/file-20220129-25-13a0oil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=767&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443257/original/file-20220129-25-13a0oil.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=767&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443257/original/file-20220129-25-13a0oil.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=767&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443257/original/file-20220129-25-13a0oil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=964&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443257/original/file-20220129-25-13a0oil.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=964&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443257/original/file-20220129-25-13a0oil.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=964&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Could the blue be inspired by the colour that the word ‘glaucous’ denotes?</span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
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<p>So, perhaps “Ulysses blue” is a homage to glaucoma (via ancient Greece and Homer). By insisting on Greek-flag blue, was Joyce seeking, through rather associative means, to insert himself into a canon of blind writers?</p>
<p>There is no definite answer to this question. But, by recognising Joyce as a disabled writer with a genuine interest in articulating a wide range of bodily and sensory experiences, we open up new possibilities for accessing Ulysses in its centenary year. We should feel empowered to read Joyce’s blue book through our eyes, <a href="https://podcasts.apple.com/gb/podcast/friends-of-shakespeare-and-company-read-ulysses-by/id1605756869">ears</a>, and <a href="https://www.ncbi.ie/shut-your-eyes-and-see-ncbi-and-james-joyce-cultural-centre-collaboration/">fingers</a>.</p><img src="https://counter.theconversation.com/content/175956/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cleo Hanaway-Oakley does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>An ode to his hero Homer? The act of a man losing his sight? What is the story behind the famous Ulysses blue.Cleo Hanaway-Oakley, Lecturer in Liberal Arts and English, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1688892021-10-04T14:27:19Z2021-10-04T14:27:19ZFrom dragonflies to kingfishers: the science behind nature’s brilliant blues<figure><img src="https://images.theconversation.com/files/424234/original/file-20211001-28-19xi5pk.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C4000%2C2658&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/kingfisher-alcedo-atthis-on-banks-river-1881747268">Kosciech/Shutterstock</a></span></figcaption></figure><p>Sitting by the edge of a river on a lazy summer’s day, the sky is a beautiful blue overhead. Lush greenery crowds the bank. The river is alive: minnows, coots and water voles fuss at the water’s edge. </p>
<p>Amid this truly delightful scene, most eye-catching of all are the brilliant flashes of blue: on the bodies of <a href="https://doi.org/10.1242/jeb.01240">dragonflies</a>, the wings of <a href="https://doi.org/10.1098/rsif.2017.0407">mallard drakes</a>, and the eye-catching feathers of any fast-gliding <a href="https://doi.org/10.1242/jeb.062620">kingfishers</a> that patrol the river.</p>
<p>These creatures gleam with the same distinctive blue we see in <a href="https://doi.org/10.1016/j.optlastec.2005.06.021">peacock plumage</a> and <a href="https://doi.org/10.1098/rspb.2002.2019">Amazon butterflies</a>. It’s a jewel-like, metallic hue that serves a particular purpose: to help these creatures stand out against their comparatively dull environment.</p>
<p>But how do these plants and animals acquire their magical blue shimmer? A true blue pigment is actually relatively rare in nature, so plants and animals instead perform tricks with the light to generate this dazzling effect.</p>
<h2>Complicated molecules</h2>
<p>In the natural world, we come across blue pigments less frequently than red, green or black pigments, because molecules that reflect blue light are inherently <a href="https://doi.org/10.2183/pjab.82.142">more complicated</a>.</p>
<figure class="align-right ">
<img alt="A peacock." src="https://images.theconversation.com/files/424248/original/file-20211001-26-ozxxti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/424248/original/file-20211001-26-ozxxti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424248/original/file-20211001-26-ozxxti.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424248/original/file-20211001-26-ozxxti.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424248/original/file-20211001-26-ozxxti.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424248/original/file-20211001-26-ozxxti.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424248/original/file-20211001-26-ozxxti.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Peacocks also have that magical blue colour.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/s/photos/peacock">Zuzanna J/Unsplash</a></span>
</figcaption>
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<p>To produce any particular colour, molecules must absorb all the light they don’t reflect. For blue pigments this means absorbing red light, which has lower energy than blue light. But low-energy light is harder to absorb, so any molecule that reflects the colour blue has to work harder to absorb red light. </p>
<p>Molecules which accommodate this process are large and complicated, making them more resource-heavy for organisms to produce. That’s why they’re less likely to turn up and persist through the long slog of evolution – they’re often too costly for organisms to maintain in the survival of the fittest.</p>
<p>Many plants and animals which are blue have evolved this way for an important reason — perhaps to entice a particular pollinator, attract a mate or warn off a predator. For example, <a href="https://www.nature.com/articles/436791a.pdf">cornflowers</a> are blue in order to attract insect pollinators, and use a complex arrangement of molecules to adapt the molecule that makes roses red so that it instead reflects blue light. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-mystery-of-the-blue-flower-natures-rare-colour-owes-its-existence-to-bee-vision-153646">The mystery of the blue flower: nature's rare colour owes its existence to bee vision</a>
</strong>
</em>
</p>
<hr>
<h2>A trick of mother nature</h2>
<p>Instead of evolving complex molecules that can absorb red light, nature has produced another trick that produces the colour blue – the process we have to thank for the iridescent blues that constitute so much of the living world’s blueness. </p>
<p>Shimmering blue biological materials are made of the same ingredients as any beetle’s back, bird’s feather or plant’s fruit (mostly the biomolecules chitin, keratin and cellulose, respectively). But these materials are essentially transparent. It’s the structure of their surfaces that makes them appear blue.</p>
<p>Rather than smooth and continuous material, such surfaces are structured with layers and ridges – or tiny spheres. These patterns create new surfaces that interact differently with the light that hits them.</p>
<figure class="align-center ">
<img alt="A blue dragonfly." src="https://images.theconversation.com/files/424249/original/file-20211001-13-1en0vbz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424249/original/file-20211001-13-1en0vbz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424249/original/file-20211001-13-1en0vbz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424249/original/file-20211001-13-1en0vbz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424249/original/file-20211001-13-1en0vbz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424249/original/file-20211001-13-1en0vbz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424249/original/file-20211001-13-1en0vbz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ever seen a dragonfly like this and wondered how it got its colour?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/blue-dragonfly-libellula-incesta-on-branch-1187497318">Michael Reilly/Shutterstock</a></span>
</figcaption>
</figure>
<p>These repeating patterns are so small that a single wavelength of blue light, which is just 450 nanometres wide, spans two pattern elements. It’s this match, between the microscopic material patterning and the width of a wavelength of light, that is crucial in deciding which colours of the spectrum are reflected back to the naked eye.</p>
<p>The size of nature’s microscopic patterning has been honed by evolution to perfectly synchronise with blue light. Even though only a small portion of blue light is reflected, with the rest passing through the transparent material, the additive effect is so strong that only a few repeats of the pattern reflect the maximum amount of blue light – two or three times stronger than pigment reflections. The rest of the colours in white light are mopped up by black pigment that lies underneath the surface.</p>
<figure class="align-center ">
<img alt="A diagram showing light reflection" src="https://images.theconversation.com/files/424490/original/file-20211004-17-xi3l8y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424490/original/file-20211004-17-xi3l8y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=525&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424490/original/file-20211004-17-xi3l8y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=525&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424490/original/file-20211004-17-xi3l8y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=525&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424490/original/file-20211004-17-xi3l8y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=659&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424490/original/file-20211004-17-xi3l8y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=659&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424490/original/file-20211004-17-xi3l8y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=659&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Certain material structures reflect only blue light, doing so more powerfully than normal pigments.</span>
<span class="attribution"><span class="source">Rox Middleton</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This astonishing effect is found in every shimmering material. It’s present on <a href="https://doi.org/10.1098/rsif.2008.0354.focus">beetles</a>, <a href="https://doi.org/10.1126/sciadv.aan8917">seaweed</a>, <a href="https://doi.org/10.1016/j.cub.2020.07.005">fruit</a>, <a href="https://doi.org/10.1080/19768354.2016.1159606">magpies</a>, <a href="https://doi.org/10.1038/nplants.2016.162">begonias</a>, and even in the glimmer of <a href="https://doi.org/10.1038/nature24285">bullseye flowers</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/bright-skies-named-colour-of-the-year-heres-why-theres-so-much-more-to-the-heavens-than-blue-168536">Bright skies named colour of the year – here's why there's so much more to the heavens than blue</a>
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</p>
<hr>
<p>Although this spectacular effect can produce any colour at all – by changing the spacing of the pattern elements – it is remarkably prevalent in blue. </p>
<p>Producing these apparently complex surfaces is actually simpler than producing natural pigment molecules that can absorb red light. It’s so effective, in fact, that the resultant brilliant, shimmering blue graces hundreds of different surfaces throughout the natural world.</p><img src="https://counter.theconversation.com/content/168889/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rox Middleton receives funding from EPSRC, BCAI, BBSRC & is a member of the Colour Group (GB).</span></em></p>True blue colour pigments are not very common in nature, so plants and animals perform tricks with the light to generate their shimmering blues.Rox Middleton, EPSRC Doctoral Prize Fellow, School of Biological Sciences, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1685362021-09-27T16:09:48Z2021-09-27T16:09:48ZBright skies named colour of the year – here’s why there’s so much more to the heavens than blue<figure><img src="https://images.theconversation.com/files/423381/original/file-20210927-13-n2x8ge.jpg?ixlib=rb-1.1.0&rect=1688%2C0%2C5854%2C3376&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/gorgeous-panorama-twilight-sky-cloud-morning-703979467">Shutterstock/C_Atta</a></span></figcaption></figure><p>The <a href="https://www.dezeen.com/2021/09/14/bright-skies-dulux-colour-year-2022/">colour of 2022</a> will be “bright skies”, according to paint manufacturer Dulux. </p>
<p>This mellow light blue may certainly seem familiar. Depending on where and at what time of the day you look at the sky, you might well expect to catch a glimpse of a similar colour. </p>
<p>Yet take the time to watch the sky from the horizon to the expanse above your head, during all weathers and from dawn to nighttime, and of course you’ll see that it is filled with many colours. Over hundreds of years, physicists have worked to understand why the sky holds so many shades, from a myriad blues to red and even green. Here’s what we’ve learned, and what to look out for while contemplating “bright skies” and immersing yourself in skywatching.</p>
<figure class="align-center ">
<img alt="Two different blue skies compared against the paint colour blue skies." src="https://images.theconversation.com/files/422726/original/file-20210922-21-fppucr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/422726/original/file-20210922-21-fppucr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/422726/original/file-20210922-21-fppucr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/422726/original/file-20210922-21-fppucr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/422726/original/file-20210922-21-fppucr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/422726/original/file-20210922-21-fppucr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/422726/original/file-20210922-21-fppucr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dulux colour Bright Skies compared against a clear blue sky near the horizon with hardly any water vapour (left) and a cloudier sky indicating higher levels of water vapour (right)</span>
<span class="attribution"><span class="source">Daniel Brown</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The Sun’s light is made up of different electromagnetic waves, and their various wavelengths are associated with a different colour. Shorter waves are seen as blue, slightly longer waves as yellow, and even longer as red.</p>
<p>When these waves are seen together they look white. But this light has to travel through our atmosphere before it gets to our eyes, and atmospheric molecules are much smaller than the wavelength of the Sun’s light. As the light hits these molecules, they scatter it in all different directions. This effect is called <a href="https://www.metlink.org/wp-content/uploads/2020/11/light_in_the_atmosphere_part_1.pdf">Rayleigh scattering</a>. </p>
<p>In this process, more of the bluer light, which has shorter wavelengths, is scattered, resulting in the sky becoming blue wherever you look. Meanwhile, the Sun becomes more yellow looking since the light from it is now missing those longer blue wavelengths.</p>
<figure class="align-center ">
<img alt="Differnt colours of the sky seen through a sculpture." src="https://images.theconversation.com/files/422725/original/file-20210922-17-a6h9i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/422725/original/file-20210922-17-a6h9i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/422725/original/file-20210922-17-a6h9i5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/422725/original/file-20210922-17-a6h9i5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/422725/original/file-20210922-17-a6h9i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/422725/original/file-20210922-17-a6h9i5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/422725/original/file-20210922-17-a6h9i5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=457&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The sky seen directly above and explored from within the Deer Shelter Skyscape installation by James Turrell in the Yorkshire Sculpture Park.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Adding white</h2>
<p>But the daytime sky isn’t the same blue all over. You’re more likely to find the Dulux bright skies colour closer to the horizon where the blue is more washed out or lighter. </p>
<p>This is the impact of <a href="https://en.wikipedia.org/wiki/Mie_scattering">Mie scattering</a>, which is a similar process as Rayleigh scattering but caused by larger particles (such as water vapour or fine pollution particles in little droplets). These types of particles remove the red, yellow and blue colour components from a white light beam in equal measures and do not alter the colour of the light passing through the atmosphere or being scattered back to an observer. This leads to the sky turning whiter in addition to the blue caused by Rayleigh scattering.</p>
<p>The influence of white within the blue of the sky becomes stronger towards the horizon where the light has to pass through much more atmosphere to arrive at the observer. The various tones and shades of blue observed become nature’s visualisation of what the atmosphere is currently composed of. The whiter it appears, the more extra particles are present.</p>
<p>A tool to measure just how many particles are suspended in the sky was developed by Horace Bénédict de Saussure, an 18th-century Swiss geologist and alpine explorer. Called a <a href="https://en.wikipedia.org/wiki/Cyanometer">cyanometer</a>, it is a colour wheel featuring 53 different colours for the observer to compare to the sky.</p>
<h2>Ozone blue at twilight</h2>
<p>If you skywatch at dusk, you’ll see a brilliant display of colour that captures intense red tones especially close to the direction of the setting sun. Since the Sun’s evening light travels through much more of our atmosphere than when the Sun is higher in the sky, by the time it reaches us it has lost much of its blue component through Rayleigh scattering. If <a href="https://skyandtelescope.org/observing/volcanoes-turn-twilights-purple/">aerosols are present higher up in the atmosphere</a> – for example caused by volcanic eruptions – this can become far more extended and colourful. </p>
<p>Once the sun is below the horizon, you will see a strong blue colour in the sky again. This cannot fully be explained by Rayleigh or Mie scattering. Instead, this is due to the presence of ozone (a colourless or pale blue gas), which does not scatter the light but absorbs it and breaks it apart. </p>
<p>Its impact is only noticeable when the rays of the sun have to pass through even more atmosphere to reach us (like when it travels from beyond the horizon). The ozone then strongly absorbs red and orange light, making the small amount of light we see in the twilight sky blue.</p>
<h2>Red and blue-green night</h2>
<p>Venture out at night in a place free of light pollution and its orange <a href="https://www.nature.com/articles/srep08409">sky glow</a> and you might notice that, despite the lack of sunlight, the nighttime sky is not black at all. Instead, we can sometimes observe what is called <a href="https://www.eso.org/public/images/potw1638a/">air glow</a>, which is our own atmosphere radiating a faint light. This is caused by atoms – mainly oxygen and nitrogen - forming molecules at an altitude of 100km-300km. </p>
<p>This glow is always present but usually too faint to see. But it contributes to the sky turning a <a href="https://www.mdpi.com/2313-433X/6/9/90/pdf">very dark red or blue-green colour</a>. You can capture it with cameras that are more sensitive than the eye. But at low light levels, our eyes lose their colour vision and merely see a grey blackness. </p>
<p>In these ways, the colours of the sky show us ways light can interact with our atmosphere. And through this science, we’ve even learnt how to recognise and explore <a href="http://www.eso.org/sci/publications/messenger/archive/no.143-mar11/messenger-no143-27-31.pdf">signs of life in the skies of planets beyond our solar system (exo-planets)</a> by analysing the light from them. Traces of an <a href="https://arxiv.org/pdf/astro-ph/0111544.pdf">atmosphere were first measured in 2001 for the exoplanet HD 209458 b</a> – sometimes called Osiris – in the constellation of Pegasus. In 2019, scientists even discovered <a href="https://arxiv.org/pdf/1909.05218.pdf">traces of water in the atmosphere of an exoplanet (K2-18 b)</a> that has temperatures that could support life as we know it.</p><img src="https://counter.theconversation.com/content/168536/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Brown does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>An astronomer’s guide to all the colours of the sky.Daniel Brown, Lecturer in Astronomy, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1536462021-01-24T18:51:17Z2021-01-24T18:51:17ZThe mystery of the blue flower: nature’s rare colour owes its existence to bee vision<figure><img src="https://images.theconversation.com/files/380133/original/file-20210122-23-whzp6l.jpg?ixlib=rb-1.1.0&rect=27%2C9%2C6011%2C3386&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>At a dinner party, or in the schoolyard, the question of favourite colour frequently results in an answer of “blue”. Why is it that humans are so fond of blue? And why does it seem to be so rare in the world of plants and animals?</p>
<p>We <a href="https://www.frontiersin.org/articles/10.3389/fpls.2020.618203/full">studied these questions</a> and concluded blue pigment is rare at least in part because it’s often difficult for plants to produce. They may only have evolved to do so when it brings them a real benefit: specifically, attracting bees or other pollinating insects.</p>
<p>We also discovered that the scarcity of blue flowers is partly due to the limits of our own eyes. From a bee’s perspective, attractive bluish flowers are much more common. </p>
<h2>A history of fascination</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/379743/original/file-20210120-21-1vt9jrw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The gold and blue funerary mask of the ancient Egyptian pharaoh Tutankhamun." src="https://images.theconversation.com/files/379743/original/file-20210120-21-1vt9jrw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/379743/original/file-20210120-21-1vt9jrw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379743/original/file-20210120-21-1vt9jrw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379743/original/file-20210120-21-1vt9jrw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379743/original/file-20210120-21-1vt9jrw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=943&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379743/original/file-20210120-21-1vt9jrw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=943&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379743/original/file-20210120-21-1vt9jrw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=943&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The ancient mask of the pharaoh Tutankhamun is decorated with lapis lazuli and turquoise.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Mask_of_Tutankhamun#/media/File:CairoEgMuseumTaaMaskMostlyPhotographed.jpg">Roland Unger / Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The ancient Egyptians were fascinated with blue flowers such as the <a href="https://en.wikipedia.org/wiki/Nymphaea_nouchali_var._caerulea">blue lotus</a>, and went to great trouble to decorate objects in blue. They used an entrancing synthetic pigment (now known as <a href="https://en.wikipedia.org/wiki/Egyptian_blue">Egyptian blue</a>) to colour vases and jewellery, and semi-precious blue gemstones such as lapis lazuli and turquoise to decorate important artefacts including the <a href="https://en.wikipedia.org/wiki/Mask_of_Tutankhamun">Mask of Tutankhamun</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/feeling-blue-get-acquainted-with-the-history-of-a-colour-49884">Feeling blue? Get acquainted with the history of a colour</a>
</strong>
</em>
</p>
<hr>
<p>Blue dye for fabric is now common, but its roots lie in ancient Peru, where an indigoid dye was used to colour cotton fabric <a href="https://advances.sciencemag.org/content/2/9/e1501623">about 6000 years ago</a>. <a href="https://en.wikipedia.org/wiki/Indigo_dye">Indigo blue dyes</a> reached Europe from India in the 16th century, and the dyes and the plants that produced them became important commodities. Their influence on human fashion and culture are still felt today, perhaps most obviously in <a href="https://en.wikipedia.org/wiki/Blue-collar_worker">blue jeans and shirts</a>. </p>
<p><a href="https://www.getty.edu/education/kids_families/do_at_home/artscoops/color_renaissance.html">Renaissance painters</a> in Europe used ground <a href="https://en.wikipedia.org/wiki/Lapis_lazuli">lapis lazuli</a> to produce dazzling works that captivated audiences. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/379770/original/file-20210120-23-1g9u2qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A painting of a woman in a vivid blue robe and white hood, with bowed head and clasped hands." src="https://images.theconversation.com/files/379770/original/file-20210120-23-1g9u2qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/379770/original/file-20210120-23-1g9u2qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=755&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379770/original/file-20210120-23-1g9u2qc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=755&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379770/original/file-20210120-23-1g9u2qc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=755&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379770/original/file-20210120-23-1g9u2qc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=948&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379770/original/file-20210120-23-1g9u2qc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=948&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379770/original/file-20210120-23-1g9u2qc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=948&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Virgin in Prayer by the Italian painter Sassoferrato, circa 1650, highlights the vivid blue colour made with ground lapis lazuli.</span>
</figcaption>
</figure>
<p>Today many blues are created with modern synthetic pigments or optical effects. The famous <a href="https://en.wikipedia.org/wiki/The_dress">blue/gold dress</a> photograph that went viral in 2015 not only shows that blue can still fascinate — it also highlights that colour is just as much a product of our perception as it is of certain wavelengths of light.</p>
<h2>Why do humans like blue so much?</h2>
<p>Colour preferences in humans are <a href="https://www.annualreviews.org/doi/abs/10.1146/annurev-psych-120710-100504">often influenced</a> by important environmental factors in our lives. An ecological explanation for humans’ common preference for blue is that it is the colour of clear sky and bodies of clean water, which are signs of good conditions. Besides the sky and water, blue is relatively rare in nature.</p>
<h2>What about blue flowers?</h2>
<p>We used a new online <a href="https://www.try-db.org/TryWeb/Home.php">plant database</a> to survey the the relative frequencies of blue flowers compared to other colours. </p>
<p>Among flowers which are pollinated without the intervention of bees or other insects (known as abiotic pollination), none were blue. </p>
<p>But when we looked at flowers that need to attract bees and other insects to move their pollen around, we started to see some blue. </p>
<p>This shows blue flowers evolved for enabling efficient pollination. Even then, <a href="https://www.frontiersin.org/files/Articles/618203/fpls-11-618203-HTML-r1/image_m/fpls-11-618203-g002.jpg">blue flowers remain relatively rare</a>, which suggests it is difficult for plants to produce such colours and may be a valuable marker of plant-pollinator fitness in an environment. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/379728/original/file-20210120-13-1r6ya5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/379728/original/file-20210120-13-1r6ya5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=650&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379728/original/file-20210120-13-1r6ya5t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=650&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379728/original/file-20210120-13-1r6ya5t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=650&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379728/original/file-20210120-13-1r6ya5t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=817&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379728/original/file-20210120-13-1r6ya5t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=817&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379728/original/file-20210120-13-1r6ya5t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=817&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Global flower colour frequency for human visual perception (A) shows when considering animal pollinated species less than 10% are blue (B), and for wind pollinated flowers almost none are observed to be blue (C).</span>
<span class="attribution"><a class="source" href="https://www.frontiersin.org/articles/10.3389/fpls.2020.618203/full">Dyer et al.</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We perceive colour due to how our eyes and brain work. Our <a href="https://en.wikipedia.org/wiki/Color_vision">visual system</a> typically has three types of cone photoreceptors that each capture light of different wavelengths (red, green and blue) from the visible spectrum. Our brains then compare information from these receptors to create a perception of colour.</p>
<p>For the flowers <a href="https://phys.org/news/2018-04-advertising-like-strategies-bees-colour-scent.html">pollinated by insects</a>, especially bees, it is interesting to consider that they have different colour vision to humans.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/inside-the-colourful-world-of-animal-vision-30878">Inside the colourful world of animal vision</a>
</strong>
</em>
</p>
<hr>
<p>Bees have photoreceptors that are sensitive to ultraviolet, blue and green wavelengths, and they also show a <a href="https://www.abc.net.au/news/science/2016-11-16/birds-and-bees-prefer-have-flower-colours-preferences/7959382?nw=0">preference for “bluish” colours</a>. The reason why bees have a preference for bluish flowers <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226469">remains an open field of research</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/379772/original/file-20210120-21-afrstb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/379772/original/file-20210120-21-afrstb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=766&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379772/original/file-20210120-21-afrstb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=766&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379772/original/file-20210120-21-afrstb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=766&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379772/original/file-20210120-21-afrstb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=963&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379772/original/file-20210120-21-afrstb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=963&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379772/original/file-20210120-21-afrstb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=963&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Various blue flowers from our study.</span>
</figcaption>
</figure>
<h2>Why understanding blue flowers is important</h2>
<p>About <a href="https://www.science.org.au/curious/everything-else/bees">one-third of our food</a> depends on insect pollination. However, world populations of bees and other insects are in decline, potentially due to <a href="https://www.pnas.org/content/118/2/e2023989118">climate change, habitat fragmentation, agricultural practices</a> and other human-caused factors.</p>
<p>The capacity of flowering plants to produce blue colours is <a href="https://link.springer.com/article/10.1007/s00442-013-2627-6">linked to land use intensity</a> including human-induced factors like artificial fertilisation, grazing, and mowing that reduce the frequency of blue flowers. In contrast, more stressful environments appear to have relatively more blue floral colours to provide resilience. </p>
<p>For example, despite the apparent rarity of blue flower colours in nature, we observed that in harsh conditions such as in the mountains of the Himalaya, blue flowers were more common than expected. This shows that in tough environments plants may have to invest a lot to attract the few available and essential bee pollinators. Blue flowers thus appear to exist to best advertise to bee pollinators when competition for pollination services is high.</p>
<h2>Knowing more about blue flowers helps protect bees</h2>
<p>Urban environments are also important habitats for pollinating insects <a href="https://iview.abc.net.au/show/great-australian-bee-challenge">including bees</a>. Having bee friendly gardens with flowers, including blue flowers that both we and bees really appreciate, is a convenient, pleasurable and potentially important contribution to enabling a sustainable future. Basically, plant and maintain a good variety of flowers, and the <a href="https://phys.org/news/2019-02-bee-eye-camera-bees-food-environment.html">pollinating insects will come</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/our-bee-eye-camera-helps-us-support-bees-grow-food-and-protect-the-environment-110022">Our 'bee-eye camera' helps us support bees, grow food and protect the environment</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/153646/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adrian Dyer receives funding from The Australian Research Council.</span></em></p>Through a bee’s eyes, blue flowers are more common than you’d think — and they could be used to monitor environmental health.Adrian Dyer, Associate Professor, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1353782020-04-03T18:01:11Z2020-04-03T18:01:11ZBlue dye from red beets – chemists devise a new pigment option<figure><img src="https://images.theconversation.com/files/324753/original/file-20200401-23143-1032w4i.jpg?ixlib=rb-1.1.0&rect=233%2C170%2C1715%2C1386&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Through the wonders of chemistry, molecules can be rearranged to completely transform color.</span> <span class="attribution"><span class="source">Erick Leite Bastos</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>What’s your favorite color? If you answered blue, you’re in good company. <a href="https://today.yougov.com/topics/lifestyle/articles-reports/2015/05/12/why-blue-worlds-favorite-color">Blue outranks all other color preferences</a> worldwide by a large margin.</p>
<p>No matter how much people enjoy looking at it, blue is a difficult color to harness from nature. As a chemist who <a href="https://www.bastoslab.com/">studies the modification of natural products</a> to solve technological problems, I realized there was a need for a safe, nontoxic, cost-effective blue dye. So my Ph.D. student, Barbara Freitas-Dörr, and I devised a <a href="https://advances.sciencemag.org/content/6/14/eaaz0421">method to convert the pigments of red beets into a blue compound</a> that can be used in a wide range of applications. We call it BeetBlue.</p>
<h2>Natural sources of blue</h2>
<p>Blue is strongly associated with nature, largely because it is reflected in the sky and on bodies of water. But compared to other colors, blue pigments are not commonly found in living organisms.</p>
<p>The feathers of many birds are blue, not because they produce a pigment, but because the microscopic structure of their <a href="https://en.wikipedia.org/wiki/Structural_coloration">feathers is able to filter light</a>. This physical phenomenon is very interesting but difficult to adopt for common applications.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/324747/original/file-20200401-23130-yhy2og.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/324747/original/file-20200401-23130-yhy2og.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/324747/original/file-20200401-23130-yhy2og.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/324747/original/file-20200401-23130-yhy2og.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/324747/original/file-20200401-23130-yhy2og.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/324747/original/file-20200401-23130-yhy2og.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/324747/original/file-20200401-23130-yhy2og.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/324747/original/file-20200401-23130-yhy2og.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The <em>Lactarius indigo</em> mushroom is one of Mother Nature’s rare examples of blue.</span>
<span class="attribution"><a class="source" href="https://de.wikipedia.org/wiki/Datei:2013-08-06_Lactarius_indigo_(Schwein.)_Fr_359786.jpg">Alan Rockerfeller/Mushroom Observer</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Plants seldom produce blue hues. When they do, their pigments rarely remain stable after extraction. The same is true for blue mushrooms like the indigo milky cap and other species that develop a blue stain when disturbed. </p>
<h2>Turning red into blue</h2>
<p>You might wonder how something red can be turned into something blue. One approach is to change the way its molecules absorb and reflect light.</p>
<p>The white light coming from your lamp contains a rainbow of colors, even though you cannot see them – without the use of a prism, that is. The surface of your red chair looks red because, at the molecular level, it is absorbing all the colors except red, which is reflected and eventually reaches your eyes.</p>
<p>The color of your chair would change from red to blue if you modified the molecular structure of its dye, making it reflect blue light instead of red. The secret is in the number of carbon atoms in the dye and how they are connected to each other. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/325053/original/file-20200402-74889-mrhg0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/325053/original/file-20200402-74889-mrhg0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/325053/original/file-20200402-74889-mrhg0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=148&fit=crop&dpr=1 600w, https://images.theconversation.com/files/325053/original/file-20200402-74889-mrhg0p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=148&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/325053/original/file-20200402-74889-mrhg0p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=148&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/325053/original/file-20200402-74889-mrhg0p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=185&fit=crop&dpr=1 754w, https://images.theconversation.com/files/325053/original/file-20200402-74889-mrhg0p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=185&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/325053/original/file-20200402-74889-mrhg0p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=185&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">By changing the structure of molecular compounds, you can alter color.</span>
<span class="attribution"><span class="source">Erick Leite Bastos</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Beets produce chemical compounds called betalains, which are natural pigments and antioxidants. The chemical structure of betalains can be modified to produce almost any hue. We realized that if we increased the number of alternating single-double bonds in betalain molecules, we could change their color from orange or magenta to blue.</p>
<p>Making blue dye with adequate intensity and light-fastness is difficult because it must absorb yellow and orange light efficiently. Solving this problem required lots of molecular tweaking.</p>
<p>My lab has been working with betalains for over 10 years to understand their function in nature and their unique chemical features, so it took only one experiment to produce BeetBlue. (It took more than two years to optimize the process, though.) </p>
<p>We broke apart the betalain molecules using alkaline water with a pH of 11. Then we mixed the resulting compound, called betalamic acid, with a commercial chemical compound called 2,4-dimethylpyrrole in an open vessel at room temperature. BeetBlue is formed almost instantly. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/FUS95BYqJ24?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">BeetBlue is created in a beaker at room temperature.</span></figcaption>
</figure>
<p>Because we changed the characteristic carbon-nitrogen chemical bond of betalains into a carbon-carbon bond, BeetBlue is a new class of pseudo-natural dyes we call quasibetalains.</p>
<h2>Color your life blue</h2>
<p>The chemical synthesis of BeetBlue is fast and very simple. In fact, it is so simple that anyone can do it if all the chemicals are available.</p>
<p>BeetBlue dissolves easily in water and other solvents, maintains its color in acidic and neutral solutions, and may provide an alternative to expensive blue colorants that often <a href="https://en.wikipedia.org/wiki/List_of_inorganic_pigments#Blue_pigments">contain toxic metals</a>, which limit the scope of their applications. </p>
<p>Live zebrafish embryos as well as cultured human cells were not affected by BeetBlue. Although more experiments are necessary to make sure it is safe for human consumption, maybe you can dye your hair, customize your clothes or color your food in the future using a dye made from beets.</p>
<p>This work shows the importance of basic science for the development of technological applications. We did not patent BeetBlue. We want people to use it freely and understand, by interacting with nature in a different and sustainable way, the future can be bright. </p>
<p>[<em>Insight, in your inbox each day.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=insight">You can get it with The Conversation’s email newsletter</a>.]</p><img src="https://counter.theconversation.com/content/135378/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Erick Leite Bastos receives funding from the São Paulo Research Foundation (FAPESP), the Brazilian National Council for Scientific and Technological Development (CNPq), and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).</span></em></p>A simple chemical reaction turns the red pigment of beets into a new, nontoxic blue dye.Erick Leite Bastos, Associate Professor of Chemistry, Universidade de São Paulo (USP)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/935412018-03-22T10:40:12Z2018-03-22T10:40:12ZRed state, blue state: How colors took sides in politics<figure><img src="https://images.theconversation.com/files/211431/original/file-20180321-165587-e2fw3u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">For decades, each party simply used a combination of red, white and blue. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/american-flag-divided-110448218?src=G5Mxq7mVR9jMZtOyP3X-9A-1-20">palbrigo/shutterstock.com</a></span></figcaption></figure><p>When Americans hear some pundits projecting a “<a href="https://www.cbsnews.com/news/wall-street-predicting-2020-election-democrat-blue-wave-biden/">blue wave</a>,” they understand that this is a prediction of a big Democratic victory. Blue of course symbolizes the Democratic party, while red represents the GOP. </p>
<p>This might seem like a long-standing tradition, but it isn’t. </p>
<p>While writing my book “<a href="https://yalebooks.yale.edu/book/9780300171877/color">On Color</a>,” I was surprised to discover that this is a recent convention, not some practice with roots dating back to the birth of the two-party system.</p>
<p>Of course, there has always been color-coding in individual political campaigns. But for years, both major parties used the full panoply of American red, white and blue for their own self-identification. </p>
<p>With the spread of color television <a href="http://www.buffalohistory.org/Explore/Exhibits/virtual_exhibits/wheels_of_power/educ_materials/television_handout.pdf">in the late 1960s</a>, color-coded electoral maps were incorporated into election coverage, but neither red nor blue had been assigned a permanent side. </p>
<p>In Cold War America, networks couldn’t consistently identify one party as “red” – the color of communists and, in particular, the Soviet Union – without being accused of bias. (The color’s connotation was objectionable enough that Cincinnati’s professional baseball team <a href="http://www.espn.com/blog/sweetspot/post/_/id/56756/tbt-when-the-reds-became-redlegs">officially changed its nickname</a> from the Reds to the Redlegs between 1953 and 1959.)</p>
<p>So depending on the election or the network, red and blue were variously assigned to Democrats and Republicans. On election night in 1980, when it became clear that Ronald Reagan was going to defeat Jimmy Carter, a television anchor pointed to the color-coded studio map showing the emerging Republican victory and <a href="http://www.nytimes.com/2004/02/08/weekinreview/ideas-trends-one-state-two-state-red-state-blue-state.html">said</a> it was starting to look like “a suburban swimming pool.” </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/PsDe-8cOSYY?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">An ocean of blue – for Reagan.</span></figcaption>
</figure>
<p>As more states went for Reagan, his campaign workers gleefully began to refer to the increasingly blue map as “Lake Reagan.” Later in the evening, with all the states decided, the electoral map registering the magnitude of Reagan’s triumph had become, in the words of another TV commentator, an “ocean of blue.” </p>
<p>But after the 2000 presidential election, no Republican victory of whatever size would ever again be described using the color blue. That year, the networks had chosen red to represent states won by the Republicans and blue to represent states won by the Democrats. However, by the end of Election Night, neither George W. Bush nor Al Gore had a definitive electoral majority to turn the country red or blue. </p>
<p>All eyes were on Florida, where the result was too close to call. </p>
<p>For the next 36 days, the country anxiously followed the television coverage of recounts and court challenges. Only on <a href="https://www.youtube.com/watch?v=L6357hHt3rQ">Dec. 12</a>, when the U.S. Supreme Court suspended the recount, did Florida officially become a “red state” – and Bush was elected the 43rd president of the United States. </p>
<p>Night after night of television coverage had fixed our political colors in the national imagination: red for Republicans and blue for Democrats. What was once discretionary and variable became a <a href="https://www.amazon.com/Red-State-Blue-Rich-Poor/dp/0691143935">permanent</a> <a href="https://www.amazon.com/Blue-Red-State-Survival-America/dp/1595589724">feature</a> of the country’s political imagery to signal the country’s ideological divide.</p>
<p>This unintended color-coding of American politics reversed the political associations of red and blue that exist almost everywhere else in the world.</p>
<p>In the United Kingdom, for example, the Conservative party color is <a href="https://assets.lbc.co.uk/2016/29/conservatives-logo---lbc-1468834487-editorial-long-form-0.jpg">blue</a>, while <a href="https://www.youtube.com/watch?v=1xJoWzPZGjY">the unofficial anthem</a> of the <a href="https://s3.eu-central-1.amazonaws.com/centaur-wp/designweek/prod/content/uploads/2015/05/labour-logo-1002x203.gif">Labour Party</a> begins “The people’s flag is deepest red.” </p>
<p>In various nations, red faces off against blue, replaying social and political divides that first assumed their ideological outlines and their primary colors in the French Revolution.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/211254/original/file-20180320-80630-1vmoigg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/211254/original/file-20180320-80630-1vmoigg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/211254/original/file-20180320-80630-1vmoigg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=758&fit=crop&dpr=1 600w, https://images.theconversation.com/files/211254/original/file-20180320-80630-1vmoigg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=758&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/211254/original/file-20180320-80630-1vmoigg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=758&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/211254/original/file-20180320-80630-1vmoigg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=953&fit=crop&dpr=1 754w, https://images.theconversation.com/files/211254/original/file-20180320-80630-1vmoigg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=953&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/211254/original/file-20180320-80630-1vmoigg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=953&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">‘Le Bonnet Rouge’ (‘The Red Hat’) was the name of an anti-government French magazine in the early 20th century.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Le_Bonnet_Rouge_c._1914.jpg">Wikimedia Commons</a></span>
</figcaption>
</figure>
<p><a href="https://www.thoughtco.com/phrygian-cap-bonnet-rouge-1221893">The bonnet rouge</a> – the soft red cap worn by the French revolutionaries – symbolized their fervor and their solidarity. It was also a defiant appropriation of the red color worn by the government’s supporters. But it would come to be solely the color of the French left, and after the revolution at the end of the 18th century, red remained their color. When the radicals briefly controlled Paris in 1848 and again in 1871, they <a href="http://www.gutenberg.org/files/10861/10861-h/10861-h.htm">raised their red flag</a> over the Hôtel de Ville.</p>
<p>The assertive red flag would become still more visible in the 20th century as the triumphal emblem of post-revolutionary Russia and of Communist China, which, along with the large Red armies and the Little Red Book, fueled the Red Scare in the United States.</p>
<p>Now, in America, red has become the color of conservatism. An accident of media history, the current colors are evidence of the randomness and instability of political color codes – though it’s unlikely Donald Trump will be selling blue “Make America Great Again” baseball caps any time soon.</p><img src="https://counter.theconversation.com/content/93541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Scott Kastan does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>While it might seem like a longstanding tradition, it’s a relatively recent phenomenon in the U.S.David Scott Kastan, George M. Bodman Professor of English, Yale UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/806552017-07-21T06:41:33Z2017-07-21T06:41:33ZBleached girls: India and its love for light skin<figure><img src="https://images.theconversation.com/files/178889/original/file-20170719-13593-ho3e72.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In India, a light complexion is associated with power, status and beauty, fueling an innovative and growing market of skin-bleaching products.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/adam_jones/13103725423">Adam Jones/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>“Let’s scrub out that tan” is a common refrain in beauty parlours in India, where girls grow up with constant reminders that only fair skin is beautiful. </p>
<p>From Sunday classified ads touting the marriageability of an “MBA graduate. 5-½ ft. English medium. Fair complexion” to elderly aunties advising young women to apply saffron paste to “maintain your skin whiter and smoother”, the signs are everywhere. </p>
<p>Even sentiments like, “She got lucky he married her despite her [dark] complexion” are still whispered around India in 2017.</p>
<p>Younger generations are now starting to push back. On July 7, 18-year-old Aranya Johar published <a href="http://aplus.com/a/aranya-johar-a-brown-girls-guide-to-beauty-poem-video?no_monetization=true">her Brown Girl’s Guide to Beauty</a> on Youtube. The video, a spoken-word poem containing lines like “Forget snow-white/say hello to chocolate brown/I’ll write my own fairy-tale” went viral, reaching 1.5 million viewers around the world in its first day alone. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ZX5soNoPiII?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Aranya Johar’s anti-bleaching poetry went viral.</span></figcaption>
</figure>
<p>Johar’s candid slam came just before <a href="http://www.ndtv.com/india-news/nawazuddin-siddiqui-hints-at-racism-tweets-about-not-being-cast-with-fair-actors-1726193">Bollywood actor Nawazuddin Siddiqui</a> used Twitter to indict the Indian film industry’s racist culture. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"886997140865564672"}"></div></p>
<p>His post recalled the vehement pushback of actress Tannishtha Chatterjee, who was <a href="http://economictimes.indiatimes.com/magazines/panache/its-2016-and-parched-actress-tannishtha-chatterjee-gets-hit-by-dark-skin-slur-on-tv-show-channel-calls-it-unfortunate/articleshow/54562692.cms">was bullied</a> for her skin tone on live TV in 2016.</p>
<p>Though many Indians still <a href="http://openscholarship.wustl.edu/cgi/viewcontent.cgi?article=1553&context=law_globalstudies">feign ignorance</a> about social discrimination based on skin colour, the country’s obsession with whiteness can also be violent. In recent years, fear of black and brown skin has also spurred harassment and attacks on <a href="http://www.aljazeera.com/indepth/features/2017/04/african-victims-racism-india-share-stories-170423093250637.html">African students living in India</a>. </p>
<p>Why do Indians so hate their own colour? </p>
<h2>The bleaching syndrome</h2>
<p>Indian history offers some answers.</p>
<p>Throughout <a href="https://books.google.fr/books?id=DSauCQAAQBAJ&redir_esc=y">medieval and modern history</a>, the Indian subcontinent has been on the radar of various European settlers and traders, including, from the 15th to 17th centuries, the Portuguese, Dutch and French. The subcontinent was invaded and partly ruled by the Mughals in the 16th century, and colonised by the British from the 17th century onwards until independence in 1947. All these foreign “visitors” were of <a href="https://www.theguardian.com/world/2015/jul/24/dark-skin-india-prejudice-whitening">relatively fair complexion</a>, and many claimed to be superior.</p>
<p>Being subject to a succession of white(ish) overlords has long associated light skin with power, status and desirability among Indians. Today, the contempt for brown skin is embraced by both the ruling class and lower castes, and reinforced daily by beauty magazine covers that feature almost exclusively Caucasian, often foreign, models. </p>
<p>It’s been the dark man’s burden in this majority-non-white nation to desire a westernised concept of beauty, and post-colonial activism has not been able to change this.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/178888/original/file-20170719-13534-1pzrjkd.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178888/original/file-20170719-13534-1pzrjkd.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178888/original/file-20170719-13534-1pzrjkd.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178888/original/file-20170719-13534-1pzrjkd.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178888/original/file-20170719-13534-1pzrjkd.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178888/original/file-20170719-13534-1pzrjkd.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178888/original/file-20170719-13534-1pzrjkd.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Indian women, like all women, come in various shapes, sizes and, yes, colours.</span>
<span class="attribution"><span class="source">Neha Mishra</span></span>
</figcaption>
</figure>
<p>According to a study we conducted from 2013 to 2016, 70% of the 300 women and men we interviewed reported wanting a date or partner with someone who had light skin. This colourism is what pushes so many Indians to lighten their skin, creating a phenomenon termed “<a href="https://www.jstor.org/stable/41675381?seq=1#page_scan_tab_contents">bleaching syndrome</a>”.</p>
<p>Bleaching syndrome is not a superficial fashion, it’s a strategy of assimilating a superior identity that reflects a deep-set belief that fair skin is better, more powerful, prettier. And it’s not limited to India; skin bleaching is also common in <a href="https://theconversation.com/tall-pale-and-handsome-why-more-asian-men-are-using-skin-whitening-products-67580">the rest of Asia</a> and <a href="https://theconversation.com/why-its-time-all-african-countries-took-a-stand-on-skin-lightening-creams-49780">in Africa</a>. </p>
<h2>A thriving bleaching market</h2>
<p>An <a href="http://www.theweekendleader.com/Causes/1249/scare-and-sell.html">inventive and growing market</a> of creams and salves has cropped up to fill this demand, which now pulls in over <a href="http://articles.economictimes.indiatimes.com/2013-08-18/news/41421066_1_fairness-cream-fairness-products-skin-colour">US$400 million dollars annually</a>.</p>
<p>Some of the most widely-sold products include Fem, Lotus, Fair and Lovely and its gendered-equivalent Fair and Handsome. Most of these appealingly named creams are in fact <a href="http://www.dailymail.co.uk/indiahome/indianews/article-2384456/Skin-whitening-creams-cause-long-term-damage-doctors-warn.html">a dangerous cocktail</a> of steroids, hydroquinone, and tretinoin, the long-term use of which can lead to health concerns like permanent pigmentation, skin cancer, liver damage and mercury poisoning among other things. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/178659/original/file-20170718-2912-15cxzd5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178659/original/file-20170718-2912-15cxzd5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178659/original/file-20170718-2912-15cxzd5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178659/original/file-20170718-2912-15cxzd5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178659/original/file-20170718-2912-15cxzd5.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178659/original/file-20170718-2912-15cxzd5.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178659/original/file-20170718-2912-15cxzd5.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Various skin-lightening products are found across India and online, no prescription or restrictions required.</span>
<span class="attribution"><span class="source">Neha Mishra</span></span>
</figcaption>
</figure>
<p>Nonetheless, a 2014 marketing study found that <a href="https://books.google.co.in/books?id=c92WBQAAQBAJ&pg=PA97&lpg=PA97&dq=fairness+high+need+area+for+indian+women&source=bl&ots=6NIPXvehgQ&sig=Ja6LcmGOnwMeI2Dh3Ap6gzAbdC8&hl=en&sa=X&ved=0ahUKEwjU-dfnoYPVAhULjZQKHY3OAjUQ6AEILzAC#v=onepage&q=fairness%20high%20need%20area%20for%20indian%20women&f=false">almost 90% of Indian girls cite skin lightening as a “high need”</a>. These young women are willing to overlook the <a href="http://www.newstatesman.com/politics/feminism/2016/01/dark-what-behind-india-s-obsession-skin-whitening">after-effects of bleaching</a>, and the advent of <a href="http://www.amazon.in/s/ref=nb_sb_ss_c_1_7?url=search-alias%3Dhpc&field-keywords=bleach+cream+for+face&sprefix=bleach+%2Chpc%2C7705&crid=2WL4X9WAM3HDR">online sales</a> allows them to use these products in the privacy of their own homes. </p>
<p>Initially focused on feminine beauty, the fairness creams market now also <a href="http://www.bbc.com/news/magazine-18268914">caters to Indian men</a>. Products marketed to men <a href="http://www.bbc.com/news/magazine-18268914">promise</a> to fight sweat, give them fairer underarms and attract women. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0kqd9zaI698?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Megastar Shahrukh Khan explains that the secret to win a woman’s heart is light skin.</span></figcaption>
</figure>
<p>And Bollywood stars with huge followings, including Shahrukh Khan and John Abraham, regularly <a href="http://www.business-standard.com/article/current-affairs/abhay-deol-names-shames-bollywood-s-biggest-for-endorsing-fairness-creams-117041200491_1.html">endorse and promote skin bleaches</a>.</p>
<h2>Bleaching backlash</h2>
<p>The brand Clean and Dry took bleaching to new levels in 2012, when it began heavily advertising for a new wash to <a href="https://www.theguardian.com/world/2015/jul/24/dark-skin-india-prejudice-whitening">lighten the vagina</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/8phEyKrxBZM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Clean and Dry intimate wash ad compares Indian vaginas and coffee.</span></figcaption>
</figure>
<p>This time, women had <a href="http://www.aljazeera.com/indepth/features/2012/07/20127108213972410.html">had enough</a>.
In 2013, the activist group <a href="http://womenofworth.in/">Women of Worth</a> launched their <a href="https://www.youtube.com/watch?v=dW3JFuZQuq8">Dark is Beautiful campaign</a>, which was endorsed by the Indian theatre actress Nandita Sen. </p>
<p>With other feminist groups, the women compelled the Advertising Standards Council of India to issue <a href="https://ascionline.org/images/pdf/fairness-advertising-code-for-wide-circulation-may-28-2014.pdf">guidelines in 2014 stating</a> that “ads should not reinforce negative social stereotyping on the basis of skin colour” or “portray people with darker skin [as]…inferior, or unsuccessful in any aspect of life particularly in relation to being attractive to the opposite sex”.</p>
<p>This guidance is in keeping with <a href="http://lawmin.nic.in/olwing/coi/coi-english/coi-4March2016.pdf">the Indian Constitution</a>, which provides for equality for all (article 14) and prohibits discrimination on the grounds of religion, race, caste, sex or place of birth (article 15). </p>
<p>Unfortunately, the law can do little to stop the subtler forms of racism and bigotry present in Indian society. And, to date, that vagina bleaching product is still <a href="https://www.apollopharmacy.in/clean-and-dry-cream-15gm.html/">on the market</a>.</p>
<p>The “bleaching syndrome” goes far beyond skin colour, with Indian women also questioning their hair texture and colour, speech, marital choices and dress style, raising real concerns about female self-esteem.</p>
<p>As Aranya Johar rhymed on Youtube, “With the hope of being able someday to love another/let’s begin by being our own first lovers”.</p><img src="https://counter.theconversation.com/content/80655/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Indian girls grow up in an environment where they are constantly reminded that fair is beautiful.Neha Mishra, Assistant Professor of Law, Reva University of BangaloreRonald E. Hall, Professor of Social Work, Michigan State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/522512016-01-08T11:19:06Z2016-01-08T11:19:06ZWhat Pantone’s colors of 2016 mean for the future of design<figure><img src="https://images.theconversation.com/files/107593/original/image-20160107-13983-1rih18g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Shades of pink and blue: for the first time, Pantone has chosen a blending of two colors. </span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-349930397/stock-photo-mountains-landscape-at-sunrise-cloudy-sky-in-pastel-colors-for-your-design-serenity-and-rose.html?src=ObCZthvk9wCL7nx6OWjJAg-1-1">'Landscape' via www.shutterstock.com</a></span></figcaption></figure><p>Pantone, the global authority on color standards for the design industries, recently announced its colors of the year for 2016: <a href="https://www.pantone.com/color-of-the-year-2016">Rose Quartz and Serenity</a>, which are muted shades of pink and blue, respectively. </p>
<p>It’s the first time Pantone has chosen <a href="http://www.pantone.com/color-of-the-year-2016?from=hpSlider">the blending of two shades</a> instead of one (past choices include <a href="http://www.pantone.com/images/pages/20758/wallpaper/Marsala_wallpaper_Pantone_Color_of_the_Year_2015-2048x1536.jpg">Marsala</a>, <a href="http://kenisahome.com/blog/wp-content/uploads/2014/03/pantone-color-of-the-year-radiant-orchid-main.jpg">Radiant Orchid</a> and <a href="http://kenisahome.com/blog/wp-content/uploads/2014/03/pantone-color-of-the-year-radiant-orchid-main.jpg">Emerald</a>). According to the company, by breaking from tradition, <a href="http://www.pantone.com/pages/fcr/?season=spring&year=2016&pid=11">it hopes to</a> “transcend cultural and gender norms.” </p>
<p>In its choice, Pantone seems to be suggesting doing away with the practice of associating colors with gender – something that’s actually a relatively recent phenomenon, and can restrict the colors designers use. For decades, pink has been associated with girls and blue with boys. Could Pantone’s decision to focus on gender influence the designs of everything, from clothing to house paints?</p>
<h2>Why am I Mr. Pink?</h2>
<p>There is nothing intrinsically female about the color pink, nor is there anything intrinsically male about the color blue. Rather, popular culture – and buckets of advertising dollars – have largely dictated how we perceive the color-gender relationship. </p>
<p>In Quentin Tarantino’s <a href="http://www.imdb.com/title/tt0105236/">Reservoir Dogs</a> (1992), five strangers chosen to commit the perfect crime sit together, presumably meeting for the first time. Each is given a colorful alias to conceal his true identity, leading to some complaints from Mr. Pink (Steve Buscemi), who’s perturbed about the name’s effeminate connotations (“Why am <em>I</em> Mr. Pink?”). </p>
<p>A century ago, viewers would have been confused by Mr. Pink’s reaction. At various points in history, these gender-color connections have actually had <em>opposite</em> roles. The color pink, which is a shade of red (the color of blood and wartime), has <a href="http://www.theatlantic.com/sexes/archive/2013/08/pink-wasnt-always-girly/278535/">historically been a masculine color</a>. Blue, a color that is <a href="http://www.nytimes.com/2006/12/24/magazine/24princess.t.html?_r=1&pagewanted=all">associated with the Virgin Mary</a>, was historically considered feminine – and still is in many parts of the world. </p>
<p>The color order that we’ve become accustomed to wasn’t established until the 1940s, when gender-specific clothing began being dictated by manufacturers and retailers. Eventually, boys and girls required different clothes, different toys – even different interior designs in their rooms and nurseries. Popular products like Barbie (primarily marketed to young females) would end up playing a role in shaping our color stereotypes. (In fact, Barbie has her own Pantone color: <a href="http://www.designboom.com/art/pantone-pink-barbie/">Barbie Pink</a>!)</p>
<p>With the arrival of the women’s liberation movement in the 1960s, fashion shifted away from gender-specific clothing as girls embraced more masculine styles. A decade later, fashion moved toward a more neutral palette. There was even a two-year stretch in the 1970s <a href="http://brooks.blogs.nytimes.com/2011/04/22/pink-and-blue/?_r=0">when <em>no</em> pink clothing appeared in the Sears, Roebuck and Co. catalogue</a>. Many argued that little girls should be dressed more like boys to encourage them to be more assertive.</p>
<p>In the 1980s, we witnessed a shift toward gender-specific color purchases, especially for children. With the advent of prenatal testing (along with more discretionary income), families could now plan farther in advance – and spend significant amounts on products – in preparation for the expected baby girl or boy. <a href="http://www.smithsonianmag.com/arts-culture/when-did-girls-start-wearing-pink-1370097/">Even disposable diapers were sold in pink and blue</a>. </p>
<h2>Colors in a gender-blurring world</h2>
<p>Today we’re more connected than ever – and <a href="https://today.yougov.com/news/2014/04/08/truth-advertising-50-dont-trust-what-they-see-read/">more skeptical about the advertising we’re exposed to</a>. Consumers have become increasingly sensitive to the methods used to reinforce these social conventions in order to bolster profits. </p>
<p>We’re also in the midst of a movement to narrow the gender divide, <a href="http://www.nytimes.com/2015/08/20/fashion/in-fashion-gender-lines-are-blurring.html">particularly in fashion</a>. The burgeoning trend of genderless fashion is being dictated by a new generation of individuals who accept styles without the traditional boundaries of previous generations. They recognize that their role as a consumer is not just about the product, but rather about being a part of a larger movement.</p>
<p>The combination of Serenity and Rose Quartz was featured on the runways for both men and women and highlighted in the <a href="https://www.pantone.com/pages/fcr/?season=Spring&year=2016">Pantone Fashion Color Report Spring 2016</a>. This will inevitably bleed into other areas of design, from interiors to product design. When conveying meaning and purpose to consumers, products and packages may abandon the use of traditional gender-color associations. As an alternative, designers could employ colors associated with emotions and lifestyles in order to to entice and connect. </p>
<p>As we’ve seen, the color-gender link isn’t concrete. The boundaries built by generations before us could soon be knocked down. With this year’s selection, Pantone is among a select few wielding a hammer. <a href="http://www.pantone.com/color-of-the-year-2016?from=hpSlider">By recognizing</a> the cultural and “societal movements towards gender equality and fluidity,” Pantone is paving the way for future generations to be less concerned about being typecast or judged for embracing unexpected and unique colors. </p>
<p>And perhaps being called Mr. Pink won’t be so insulting after all.</p><img src="https://counter.theconversation.com/content/52251/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Russell does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The global color authority seems intent on obliterating the confines of gender-color associations.Ryan Russell, Associate Professor of Graphic Design, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/498842015-11-12T03:08:15Z2015-11-12T03:08:15ZFeeling blue? Get acquainted with the history of a colour<figure><img src="https://images.theconversation.com/files/101395/original/image-20151110-21211-42101n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A new exhibition examines the meaning and enduring influence of the colour blue. </span> <span class="attribution"><span class="source">National Gallery of Victoria</span></span></figcaption></figure><p>We’re used to thinking about the colour blue symbolically. We might have the blues, see ourselves as blue-collar workers, or receive unsettling news as a bolt from the blue. But the colour’s historical significance predates those associations by a long stretch. </p>
<p><a href="http://www.ngv.vic.gov.au/exhibition/blue/">Blue: Alchemy of a Colour</a>, currently showing at the National Gallery of Victoria (NGV) in Melbourne, examines Asian and European works of art employing the colour blue from the 7th century AD to the present. </p>
<p>Comprising more than 60 ceramics, paintings, prints and textiles the exhibition focuses on cobalt blue and indigo, two of the most distinctive and influential colourants employed worldwide. And yet, in their raw states, neither substance is actually blue. Cobalt is a silvery-white mineral; indigo is a greenish plant extract. </p>
<p>It is only through complex processing, requiring considerable technical knowledge, that both substances assume the brilliant blue hues beloved of ceramicists and textile artists the world over. So let’s look a little closer. </p>
<h2>Indigo</h2>
<p>Indigo blue is used as a dye for textiles and a pigment for paintings and prints. It is sourced from a range of plants, the best known of which is <em><a href="http://www.motherherbs.com/indigofera-tinctoria.html">Indigofera tinctoria</a></em> (“True” indigo), which has been used to dye textiles in India from before 2000BC. </p>
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<figcaption>
<span class="caption">Indigofera tinctoria.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>The use of indigo dye to colour cloth blue is a worldwide phenomenon, reflecting both the widespread availability of plants that contain indigotin, the active ingredient in indigo dye, and the dye’s colourfastness. Although indigo was available in Europe in the form of woad (<em><a href="https://en.wikipedia.org/wiki/Isatis_tinctoria">Isatis tinctoria</a></em>), the far more potent <em>Indigofera tinctoria</em>, used in India and across tropical Asia, was imported into Europe in enormous quantities from the beginning of the 16th century. </p>
<p>The NGV’s exhibition explores techniques employed to pattern indigo-dyed cloth in textiles from Egypt, Japan, China, Central Asia, India, Indonesia and Italy. Patterning with printed, painted and tied resists, such as <a href="https://en.wikipedia.org/wiki/Batik">batik</a>, <a href="https://en.wikipedia.org/wiki/Japanese_handicrafts">yuzen</a> and <a href="https://en.wikipedia.org/wiki/Ikat">ikat</a>, which produce a white pattern on an indigo blue field, are contrasted with positive blue patterns produced by printing or weaving.</p>
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<span class="caption"></span>
<span class="attribution"><span class="source">National Gallery of Victoria</span></span>
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<p>Indigo blue textiles often have particular symbolic resonances. </p>
<p>Central Asian Turkmen women wear a distinctive garment in the form of an embroidered mantle with long vestigial sleeves called a <a href="http://www.metmuseum.org/toah/works-of-art/1999.141">chyrpy</a>. The colour of the ground fabric indicates the wearer’s age: a young woman wears a dark blue chyrpy, a middle-aged woman wears yellow, and a woman aged over 60 wears white. </p>
<p>Elsewhere in Central Asia, in the towns along the silk road where sumptuously patterned fabrics were produced using the ikat resist technique, garments in dark blue indigo dyed silk and cotton fabric (adras) with white patterns were thought appropriate for older women and those in mourning. </p>
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<span class="caption"></span>
<span class="attribution"><span class="source">National Gallery of Victoria</span></span>
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<p>The ubiquity of indigo dye has resulted in blue becoming the colour of the everyday <a href="https://theconversation.com/fashioning-blue-collars-chambray-shirts-and-indigo-dyed-workwear-24603">clothes of the working class</a> in Europe and Asia. But predominantly blue textiles and garments are also some of the most prestigious textiles, imparting status to the wearer and worn on important ritual occasions. </p>
<p>Their prestige may be signified by the of valuable materials such as gold and beads, the incorporation of extra colours, patterns and techniques, or special finishes. </p>
<p>In China the colour blue generally signifies the natural world, springtime, youth and immortality. The emperor wore a blue court garment at annual ceremonies associated with the heavens and crops, and indigo blue was the most common ground colour of Manchu clothing during the <a href="http://www.britannica.com/topic/Qing-dynasty">Qing dynasty</a> (1644–1912AD). </p>
<p>Deceptively simple blue cloths may also convey status through their association with important rituals. Indigo dyed <em><a href="http://the-arts-collection.blogspot.com.au/2011/08/ulos-sibolang.html">ulos sibolang</a></em> are probably among the oldest textile types woven by the <a href="http://www.britannica.com/topic/Batak">Toba Batak</a> people of north Sumatra, Indonesia.</p>
<p>They are important ceremonial cloths given by the bride, and are also given as gifts at funerals and were worn as a headcloth by widows and used to cover the corpse. </p>
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<a href="https://images.theconversation.com/files/101656/original/image-20151112-9396-2a3949.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/101656/original/image-20151112-9396-2a3949.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/101656/original/image-20151112-9396-2a3949.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/101656/original/image-20151112-9396-2a3949.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/101656/original/image-20151112-9396-2a3949.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/101656/original/image-20151112-9396-2a3949.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/101656/original/image-20151112-9396-2a3949.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/101656/original/image-20151112-9396-2a3949.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption"></span>
<span class="attribution"><span class="source">National Gallery of Victoria</span></span>
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<h2>Cobalt</h2>
<p>Cobalt was also used in Babylonia, an area rich in cobalt deposits, as early as the 6th century BC to produce blue-glazed stonewares. The first evidence for Chinese use of cobalt to produce blue-decorated ceramics is found during the <a href="http://www.ushistory.org/civ/9d.asp">T’ang dynasty</a> (618–906AD). </p>
<p>The succeeding <a href="http://www.britannica.com/topic/Song-dynasty">Song dynasty</a> showed little interest in cobalt blue, preferring ceramics in subtle monochrome colours inspired by the love of jade. It is with the <a href="http://www.britannica.com/topic/Yuan-dynasty">Yuan dynasty</a> (1278–1368AD) that white porcelain decorated with underglaze cobalt blue began to be produced in quantity.</p>
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<figcaption>
<span class="caption">Tomb of Safi-ad-din, in Ardabil, Iran.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>It appears that the impetus for producing those ceramics probably came from outside China’s borders. The Persians greatly admired Chinese porcelain but were unable to produce this high-fired ceramic body themselves. </p>
<p>Their own ceramic tradition, heir to the knowledge of the Babylonian ceramicists, employed cobalt blue decoration on stonewares. Evidence suggests that the Persians began commissioning and importing blue-and-white porcelain from the Chinese kilns; it is probably no coincidence that today one of the largest collections of Yuan blue-and-white porcelain is to be found at the <a href="https://en.wikipedia.org/wiki/Ardabil">Ardabil shrine</a> in Iran. </p>
<p>It is also likely that the cobalt used in Yuan blue-and-white wears was imported from Iran. China had access to cobalt sources of its own, but these were generally of poorer quality than the imported “Islamic blue”, as it was called in Chinese documents. </p>
<p>Both Yuan China and Ilkhanid Iran were ruled by Mongolian dynasties; trade and cultural exchange between the two regions was intense and constant. It has been suggested that the blue and white palette would have appealed greatly to the Mongolians as a symbol of their power uniting heaven (blue) and earth (white). </p>
<p>That the birth of the Chinese blue-and-white porcelain tradition was the result of complex cross-cultural interactions is further suggested by the fact that many of the motifs employed on Yuan blue-and-white ware appear related to Uighur and Mongol textile designs. </p>
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<span class="caption"></span>
<span class="attribution"><span class="source">National Gallery of Australia</span></span>
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<p>By the advent of the <a href="http://www.travelchinaguide.com/intro/history/ming.htm">Ming dynasty</a> (1368–1644AD) blue-and-white porcelain was being produced in enormous quantities at the kilns of Jingdezhen. Imports of cobalt from Persia could not match the growing demand for the mineral and Chinese cobalt sources began to be exploited with ever greater intensity. </p>
<p>It was this Ming blue-and-white that began to reach Europe in small quantities, igniting a European passion for these marvellous ceramics and stimulating the quest to discover the secret of their production. </p>
<h2>Out of the blue</h2>
<p>It is one of history’s great coincidences that, at the same time that true indigo was introduced to Europe from India in the 16th century, Chinese blue-and-white porcelain was also beginning to arrive there in significant quantities. The craze for Chinese porcelain saw the striking blue-and-white colour palette become the height of European fashion. </p>
<p>Chinese porcelain also provided Europeans with an entirely new visual vocabulary of patterns, motifs and compositional principles, and these very quickly migrated from ceramics to influence the decoration of artworks executed in other media, including textiles. </p>
<p>The two colourants – cobalt and indigo – undoubtedly reinforced each other’s popularity. The textiles and ceramics produced with these colourants were the objects of trade and artistic exchange which has seen them traverse the whole of the globe.</p>
<p><br></p>
<p><em>Blue: Alchemy of a Colour is at the National Gallery of Victoria, Melbourne, until March 2016. Details <a href="http://www.ngv.vic.gov.au/exhibition/blue/">here</a></em>.</p><img src="https://counter.theconversation.com/content/49884/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew Martin is Curator of International Decorative Arts at the National Gallery of Victoria and the co-curator of the exhibition Blue: Alchemy of a Colour. </span></em></p>Blue crops up in all sorts of idioms and registers. But, as a new National Gallery of Victoria exhibition demonstrates, there’s more to the colour, and its long history, than meets the eye.Matthew Martin, Research fellow at the Melbourne University of Divinity, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.