The Color Blue: Super Hero or Nature’s Great Hoax?

Ann’s blog today is about the color purple, and because we always strive to maintain the illusion that we are a well-coordinated blogging team, I decided to come up with a complementary color to discuss in Andy’s Corner. Purple is a combination of red and blue, so it seemed to make sense to select one of those colors. For reasons that are obvious but will be left unstated (we try to avoid discussing politics here at BigLittleMeals), the color red has steadily lost ground on my preferred colors list. Blue, on the other hand has much going for it, even if it’s not always what we think it may be.

Will blue paint be as difficult to come by as toilet paper was in 2020?.

To begin with, there can be little disagreement that the color blue has lots of fans. Natalie Angier reports in a NY Times piece that studies have repeatedly shown that “blue love” is a global affair. When people are asked their favorite color “in most parts of the world roughly half will say blue, a figure three to four times the support accorded common second-place finishers like purple or green.” A recent article in Homes & Gardens reports that blue is the top go-to paint color in the U.S., even though, tragically, manufacturers “are sounding alarm bells” because it is in short supply leaving interior designers distraught.

But blue is much more complicated than merely being a pretty face with sexy 450 to 495 nanometer wavelengths on the visible spectrum. Angier suggests that historically, blue may have influenced our cultural notions of “virtue, authority, divinity and social class,” which is more than we can say about red. And, as if that weren’t enough, she cites research indicating that the color blue promotes calmness and open-endedness, “in contrast to the aggressive specificity associated with red.”

I’m guessing that when deciding on a color for their Viagra pills the marketing folks at Pfizer were unaware that blue “promotes calmness.

There’s more. The color blue has been shown to suppress appetite (maybe instead of going on a diet, you should try putting a blue light in your fridge). Additionally, computer screens that are blue have been found to increase creativity (although not productivity). Also, researchers have confirmed that children in medical clinics react more positively to caretakers attired in blue than those in other colors.

Is blue a color preferred by mosquitoes?

On the downside, blue can imply coldness, sorrow and death (all common topics in “blues” music lyrics). And just to throw in a bonus downer, there is some evidence that blue is a favorite color of mosquitoes.

[editor’s note: I was unable to independently verify that mosquitoes fancy blue but I did come across a research article that probably has the answer, if only I could understand it, : “Circadian Regulation of Light-Evoked Attraction and Avoidance Behaviors in Daytime- versus Nighttime-Biting Mosquitoes.“]

For those who want to find out how complex (and fascinating) blue can really be, I recommend Kai Kupferschmidt’s recent book, Blue: In Search of Nature’s Rarest Color.

But what fascinates me most of all about the color blue is that in a literal sense it is one of the great hoaxes of nature. I first got an inkling of this when I was doing research on bluebirds for a previous Andy’s Corner post with the catchy title Bluebird Blues: Debunking the Myth of the Bluebird of Happiness. In that piece, I wrote that bluebirds are not actually blue but only appear to be so due some perceptual quirk associated with light waves. To quote myself:

While I don’t really understand how light waves affect our perception, I do understand why bluebirds might be more than a little annoyed knowing that they have been erroneously named for centuries.

But it wasn’t until I started thinking about today’s blog and doing some research that I learned how widespread this hoax is. Kai Kupferschmidt, in his fascinating book, Blue: In Search of Nature’s Rarest Color, tells us that, with a few notable exceptions, the blue things we see in nature are blue not because of colored pigments (the source of most colors we see) but because of how light waves are absorbed or reflected by the object. In other words, our eyes are tricked into believing that we are seeing blue. I came across this somewhat technical explanation about “blue” feathers in a National Geographic article:

[some] birds look blue, but they’re not. They’re posers. Frauds. Impersonators...

Blue on bird feathers is a “structural color.” It is created by the 3-D structure of proteins on the birds’ feathers. The structures are called nanochannels and the proteins are called keratins.

When white light strikes a blue feather, the keratin pattern causes red and yellow wavelengths to cancel each other out, while blue wavelengths of light reinforce and amplify one another and reflect back to the beholder’s eye …

It’s not only bird feathers that trick us into believing we are seeing blue. Take dog fur for example. I’m quite familiar with blue merle dogs, especially Australian shepherds, but never realized that they carry no blue gene for that color; it is the result of what is called a “dilution gene.” The blue merle color we see is just a diluted form of black.

... if you look at a blue merle dog, which is really a black dog with the merle dilution gene, you’ll notice that while much of the dog is a slate blue, there are still some patches of black. These darker patches are where the dilution isn’t as strong, so you can see the original color of the dog if the dilution gene wasn’t present. (Juniper Pets)

Like Ann, our cat Choco has captivating blue eyes, albeit a bit more crossed.

But what really blew me away (pun intended) was discovering that blue eyes are also part of nature’s big hoax. I hesitate to bring this up knowing that Ann occasionally reads my part of the blog, but journalistic integrity compels me to pursue this issue. Just to be safe, let me preface this by pointing out that Ann has what I consider to be very attractive blue eyes. In fact, just the other day we were chatting with a complete stranger who spontaneously told Ann that she had pretty blue eyes – it totally made her day.

Now here’s the kicker: that alluring blue color is from eyes with no blue pigmentation. If you were to dissect one of those eyes (heaven forbid!) you would find that the actual pigment is brownish black, evidently having to do with something called melanin. Wikipedia offers probably more than you want to know about this:

Unlike brown eyes, blue eyes have low concentrations of melanin in the stroma of the iris, which lies in front of the dark epithelium. Longer wavelengths of light tend to be absorbed by the dark underlying epithelium, while shorter wavelengths are reflected and undergo Rayleigh scattering in the turbid medium of the stroma. This is the same frequency-dependence of scattering that accounts for the blue appearance of the sky [editor’s note: don’t get me started on the sky!] The result is a “Tyndall blue” structural color that varies with external lighting conditions.

So, if you find yourself gazing into the blue eyes of your partner try not to think about the fact that you are actually peering into some brownish black pigment of the epithelium that you can’t see because the blue wavelengths are getting in the way. That surely would take the romance out of things. It’s probably best to go along with the hoax and enjoy it.


  1. David Ewing says:

    Hmmm. Andy speaks as if there were such a thing as “blue” in the world outside our heads. What is out there (if anything) is a very wide range of electromagnetic radiation in wavelengths along a continuously variable spectrum. Our sensory apparatus is tuned to detect a small fraction of the range and our “perceptuolinguisticocultural” apparatus assigns the names of colors to more or less arbitrary segments of the fraction. Different cultural and linguistic groups slice it up in different ways. He speaks of “blue pigment” as if that were something real, i.e. a truly blue thing. But we see blue things as blue only because of the way light interacts with them, just as with the “non-blue” things he adduces. Basically, colors are just something we made up. The alarming thing to me is that this seems to be true also of pretty much the entire universe we (think we) occupy. But of course I just made this up, too.


    • theRaggedys says:

      Thanks for your input. I do consider myself somewhat of a social constructionist so I couldn’t agree more with your observations about our “perceptuolinguisticocultural” apparatus. Although I am certainly no expert on the nature of pigments and how we perceive (or label) colors, I’ve come across a number of sources that suggest a difference between colors from “natural pigments” and those that are “structural.” An article in the science section of The Atlantic Magazine (June 20, 2021) entitled “Blue Animals Are Different From All the Rest” summarizes much of this argument( In any case, it is alway fun to think about these things, made up or not.


  2. Larry Squarepants says:

    Hi Andy–– You illustration of the visible light spectrum reminded me of this Elon Musk quote:

    “When I was a little kid I was really scared of the dark. But then I came to understand dark just means the absence of photons in the visible wavelength––400 to 700 nanometers. Then I thought well it’s silly to be scared of a lack of photons. Then I wasn’t afraid of the dark anymore.”


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