By Mindy Weisberger published September 06, 2021
Feeling blue? That color isn't as common as you may think.
感到憂鬱？那種顏色不像你能想像的常見。
圖1. 在毒箭蛙中，明亮的藍色向捕食者傳達，該動物有毒的警告。
When you look up at the blue sky overhead or gaze across the seemingly endless expanse of a blue ocean, you might think that the color blue is common in nature.
But among all the hues found in rocks, plants and flowers, or in the fur, feathers, scales and skin of animals, blue is surprisingly scarce.
當您仰望頭頂的藍天，或凝視看似一望無際的藍色海洋時。您可能認為，於大自然中，藍色很常見。不過，在岩石、植物及花卉，或在動物的皮毛、羽毛、鱗片及皮膚中，發現的所有顏色中，藍色出人意外地稀少。
But why is the color blue so rare? The answer stems from the chemistry and physics of how colors are produced — and how we see them. We're able to see color because each of our eyes contains between 6 million and 7 million light-sensitive cells called cones.
不過，為何藍的這種顏色如此罕見？答案源自顏色如何產生的化學反應及物理現象，及我們如何看見它們。我們能看見顏色，是因為我們的每隻眼睛，具有6百萬到7百萬個，被稱為視錐的光敏感細胞。
There are three different types of cones in the eye of a person with normal color vision, and each cone type is most sensitive to a particular wavelength of light: red, green or blue. Information from millions of cones reaches our brains as electrical signals that communicate all the types of light reflected by what we see, which is then interpreted as different shades of color.
在具有正常顏色視覺的人眼睛中，有三種不同類型視錐細胞。每一種視錐細胞，對特定波長的光最為敏感：紅色、綠色或藍色。來自數百萬視錐細胞的信息，以傳達由我們看到所反射之所有類型光的電氣信號，到達我們的大腦，然後被體現為不同色度的顏色。
When we look at a colorful object, such as a sparkling sapphire or a vibrant hydrangea bloom, "the object is absorbing some of the white light that falls onto it; because it's absorbing some of the light, the rest of the light that's reflected has a color," science writer Kai Kupferschmidt, author of "Blue: In Search of Nature's Rarest Color" (The Experiment, 2021), told Live Science.
當我們注視，諸如閃閃發光的藍寶石，或色彩鮮明之繡球花盛開的色彩豐富物體時，2021年 "藍色：尋找大自然最稀有顏色" 的實驗撰文人，科學作家Kai Kupferschmidt告訴 Live Science：「是因為，物體吸收一些落在其上的白光；由於吸收白光的一些光，其餘被反射的光具有一種顏色。」
"When you see a blue flower — for instance, a cornflower — you see the cornflower as blue because it absorbs the red part of the spectrum," Kupferschmidt said. Or to put it another way, the flower appears blue because that color is the part of the spectrum that the blossom rejected, Kupferschmidt wrote in his book, which explores the science and nature of this popular hue.
Kupferschmidt宣稱：「當你看到一朵藍色的花(譬如矢車菊)，你看到矢車菊為藍色，因為它吸收了光譜中的紅色部分。」Kupferschmidt在其探索這種大眾化色調之科學及本質的書中記述，或換一種說法，此種花朵呈現藍色，因為那種顏色是此種花拒絕的光譜部分。
In the visible spectrum, red has long wavelengths, meaning it is very low-energy compared with other colors. For a flower to appear blue, "it needs to be able to produce a molecule that can absorb very small amounts of energy," in order to absorb the red part of the spectrum, Kupferschmidt said.
在可見光譜中，紅色具有長的波長。這意味著，與其他顏色相較下，這是非常低能量。就一朵呈現藍色的花而言，為了吸收光譜的紅色部分。Kupferschmidt宣稱：「它需要能產生一種，能吸收非常少能量的分子。」
Generating such molecules — which are large and complex — is difficult for plants to do, which is why blue flowers are produced by fewer than 10% of the world's nearly 300,000 flowering plant species.
對植物而言，產生如此大且複雜的分子，很難做到。這是為何世界上，近30萬開花植物的物種，不到10%生產藍色花朵。
One possible driver for the evolution of blue flowers is that blue is highly visible to pollinators such as bees, and producing blue blossoms may benefit plants in ecosystems where competition for pollinators is high, Adrian Dyer, an associate professor and vision scientist at the Royal Melbourne Institute of Technology in Melbourne, Australia, told the Australian Broadcasting Company in 2016.
於2016年，澳大利亞皇家墨爾本理工學院(位於墨爾本市)副教授暨視覺科學家，Adrian Dyer告訴澳大利亞廣播公司，藍色花朵演化的一種可能驅動因素，是藍色對蜜蜂等傳粉媒介高度可見，因此產生藍色花朵可能有利於，在傳粉媒介競爭激烈之生態系統中的植物。
As for minerals, their crystal structures interact with ions (charged atoms or molecules) to determine which parts of the spectrum are absorbed and which are reflected. The mineral lapis lazuli, which is mined primarily in Afghanistan and produces the rare blue pigment ultramarine, contains trisulfide ions — three sulfur atoms bound together inside a crystal lattice— that can release or bind a single electron.
至於礦物，其晶體結構與離子(帶電原子或分子)交互作用，來確定光譜的哪些部分被吸收，哪些被反射。主要在阿富汗開採、生產稀有藍色顏料群青的青金石礦物，具有能釋出或結合一個電子的三硫化物離子(三個硫原子在一晶格內結合在一起的離子)。
"That energy difference is what makes the blue," Kupferschmidt said. Blue animals' colors don't come from chemical pigments. Rather, they rely on physics to create a blue appearance.
Kupferschmidt宣稱：「使呈現出藍色的是，那種能量差異。」藍色動物的顏色不是來自化學顏料。而是，它們仰賴物理現象，來產生藍色外觀。
Blue-winged butterflies in the Morpho genus have intricate, layered nanostructures on their wing scales that manipulate layers of light so that some colors cancel each other out and only blue is reflected; a similar effect happens in structures found in the feathers of blue jays (Cyanocitta cristata), the scales of blue tangs (Paracanthurus hepatus) and the flashing rings of venomous blue-ringed octopuses (Hapalochlaena maculosa).
於閃蝶屬中的藍色蝶翼蝴蝶，在其操縱光層的蝶翼鱗上，具有複雜、分層的奈米結構，這些納米結構可以操縱光層，以便某些顏色相互抵消，僅反射藍色；這是一種發生於北美藍樫鳥(Cyanocitta cristata)羽毛結構、藍唐 (Paracanthurus hepatus)鱗片及有毒藍環章魚(Hapalochlaena maculosa)閃爍之環中，被發現的類似效應。
Blue shades in mammals are even rarer than in birds, fish, reptiles and insects. Some whales and dolphins have bluish skin; primates such as golden snub-nosed monkeys (Rhinopithecus roxellana) have blue-skinned faces; and mandrills (Mandrillus sphinx) have blue faces and blue rear ends.
於哺乳動物中，藍色色調比鳥類、魚類、爬行動物及昆蟲更為罕見。有些鯨魚及海豚具有藍色皮膚；諸如金色獅子鼻猴(金絲猴，Rhinopithecus roxellana)等，靈長目動物具有藍色皮膚的臉；及彩面山魈(Mandrillus sphinx)有藍色的臉及臀部。
But fur — a trait shared by most terrestrial mammals — is never naturally bright blue (at least, not in visible light. Researchers recently found that platypus fur glows in vivid shades of blue and green when exposed to ultraviolet (UV) rays, Live Science previously reported).
不過，大多數陸地哺乳動物共有的特徵—皮毛，未曾是天生亮藍色。(至少，在可見光下不是。最近，研究人員們發現，鴨嘴獸的皮毛，當暴露於紫外線(UV)時，發出鮮明的藍色及綠色色調，Live Science先前報導過)。
"But it takes a lot of work to make this blue, and so the other question becomes: What are the evolutionary reasons to make blue? What's the incentive?" Kupferschmidt said. "The fascinating thing when you dive into these animal worlds is always, who's the recipient of this message and can they see the blue?"
Kupferschmidt宣稱：「不過，這需要很多工作，來產生藍色。因此，出現了另一問題：什麼是產生藍色的演化原因？動機是什麼？當你埋首於此些動物世界時，最令人著迷的事總是，誰是此信息的接收者，它們能看到藍色嗎？」
For example, while humans have three light-sensing receptor types in our eyes, birds have a fourth receptor type for sensing UV light. Feathers that appear blue to human eyes "actually reflect even more UV light than blue light," Kupferschmidt explained.
譬如，儘管人類在眼睛中，有三種感光受體類型，不過鳥類有第四種感知紫外線的受體類型。Kupferschmidt 解釋，對人類眼睛顯現藍色的羽毛，"實際上反射的紫外線光，比藍光更多得多"。
By that reasoning, the birds that we call blue tits (Cyanistes caeruleus) "would probably call themselves 'UV tits,' because that's what they would mostly see," he said.
他表示，按照那種推理。我們稱為藍山雀(Cyanistes caeruleus)的鳥類，"或許能自稱'紫外線山雀'。因為，那是它們最能看到的"。
Because of blue's scarcity in nature, the word for blue was a relative latecomer to languages around the world, appearing after the words for black, white, red and yellow, according to Kupferschmidt.
根據Kupferschmidt的說法，在大自然中，由於藍色的罕見。在世界各地的語言中，藍色是一個相對較晚的詞，出現在黑色、白色、紅色及黃色的詞之後。
"One theory for this is that you really only need to name a color once you can dye things — once you can divorce the color from its object. Otherwise, you don't really need the name for the color," he explained. "Dyeing things blue or finding a blue pigment happened really late in most cultures, and you can see that in the linguistics."
他解釋：「就此的一個理論是，一旦能染色東西，只要能使該顏色與其物體分離，確實只需取名為一種顏色。否則，真的不需要顏色的名稱。在大多數文化中，將東西染成藍色，或找到藍色顏料，皆很晚發生。這能在語言學中發現。」
The earliest use of blue dye dates to about 6,000 years ago in Peru, and the ancient Egyptians combined silica, calcium oxide and copper oxide to create a long-lasting blue pigment known as irtyu for decorating statues, researchers reported Jan. 15 in the journal Frontiers in Plant Science.
研究人員們，在2021年1月15日，於《植物科學前沿》期刊報告，藍色染料的最早使用，溯至大約6千年前的秘魯。而古埃及人混合了二氧化矽、氧化鈣及氧化銅，創造出一種用於裝飾雕像，被通稱為irtyu的持久性藍色顏料。
Ultramarine, a vivid blue pigment ground from lapis lazuli, was as precious as gold in medieval Europe, and was reserved primarily for illustrating illuminated manuscripts.
群青是一種，從青金石研磨成的鮮豔藍色顏料。在中世紀的歐洲，與黃金一樣珍貴，主要被儲備，來顯示經照明的手稿。
Blue's rarity meant that people viewed it as a high-status color for thousands of years. Blue has long been associated with the Hindu deity Krishna and with the Christian Virgin Mary, and artists who were famously inspired by blue in nature include Michelangelo, Gauguin, Picasso and Van Gogh, according to the Frontiers in Plant Science study.
藍色的罕見性意味著，數千年來，人們將其視為一種高身分地位的顏色。 根據於《植物科學前沿》期刊的研究説法，藍色長期以來一直與印度教的克里希納(Krishna)神及基督教聖母瑪利亞，被聯繫在一起。而受到大自然中，藍色啟發的著名藝術家，包括米開朗基羅、高更、畢加索及梵谷。
"The relative scarcity of blue available in natural pigments likely fueled our fascination," the scientists wrote.
此些科學家記述：「於天然顏料中，藍色可資使用的相對缺乏性，很可能助長了人們的強烈愛好(迷戀)。」
Blue also colors our expressions, appearing in dozens of English idioms: You can work a blue-collar job, swear a blue streak, sink into a blue funk or talk until you're blue in the face, to name just a few. And blue can sometimes mean contradictory things depending on the idiom: "'Blue sky ahead' means a bright future, but 'feeling blue' is being sad," Kupferschmidt said.
藍色也為人們，出現在幾十個英語習語中的表達上，增添色彩：僅舉幾例，從事一份藍領工作、不斷發誓、陷入藍色恐懼或說個不停直到臉色發青。 取決於習語，藍色有時能意味著，相互矛盾的事物。Kupferschmidt宣稱：「'前方的藍天'意味著，光明的未來。不過，'感覺藍色'是悲傷的。」
Blue’s scarcity in nature may have helped shape our perception of the color and things that appear blue. "With blue, it's like a whole canvas that you can still paint on," Kupferschmidt said. "Maybe because it is rare in nature and maybe because we associate it with things that we can't really touch, like the sky and the sea, it's something that is very open to different associations."
在大自然中，藍色的缺乏性可能曾有助於，塑造人們對顏色及顯現藍色事物的感知。Kupferschmidt宣稱：「有了藍色，它就像一整個畫布，你仍然可以在上面畫畫。許因為它在大自然中很罕見，及也許因為人們將它與無法真正觸摸的事物聯繫起來，譬如天空及大海。它對於不同的聯想，那是非常開放的。」
網址：https://www.livescience.com/why-blue-rare-in-nature.html
翻譯：許東榮
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