In a new book, an evolutionary biologist explains why blue didn’t ‘exist’ a few centuries ago

While I finish my morning coffee, Oreo fixes me with an incredulous stare. He has long since finished his breakfast, and is appalled at my inability to keep pace with him as he gobbles down his food.

“What do you want, Oreo?”

He rolls his eyes, and points to his leash. I can almost hear him thinking, “This human takes forever to train, and she keeps forgetting every day again?” When I don’t move, he walks up to me and puts his paw on me and stares intently. I have been given the final warning. I understand when I am defeated. We must go now. So let’s do that.

As I put my hands on the leash, the little boy in front of me transforms. His tail wags with an intensity that puts the best propellers to shame, and he jumps up and down like a spring toy wound up to the maximum possible limit. I am in awe of the joy that this boy has every single time we go for a walk.

Living with Oreo has taught me a great deal, and one of the biggest lessons has been learning how to enjoy small moments like this one. As we walk outside, I see remnants the rain from last night. There are tiny little droplets stuck to the surface of leaves, making everything smell fresh and clean.

Something about this morning brings up a memory, like a sleeper agent being triggered by a keyword. There was a classic drawing I was taught to make as a child – as most Indian kids of my generation probably were – two triangles for mountains, a semi-circular sun between them and a very blue river. I would use brown sketch pens for the mountains, an orange one for the sun and a blue one for the river. ‘The colours were intense, and I used a scale to get the mountains exactly right.

There were several things wrong with that drawing – or rather, the image was somewhat distant from reality.

Mountains aren’t solid brown, and rivers aren’t solid blue with dark blue squiggly lines, are they? In fact, if you were born a few centuries ago, nothing was blue.

“That can’t be right,” you might say, and Oreo seems to agree, giving me that sceptical side-eye he reserves for when I’m behaving particularly bizarrely (or delaying going for a walk). “The sky has always been blue, so have the oceans, and surely there must be lots of blue things in nature?” I mean, it’s practically a universal example of irrefutable truth.

As if on command, an actress on a loud TV playing in a neighbour’s house casually asks, “Why do we like makeup montages? I don’t know. Why is the sky blue?”

My answer to the first question: It gives me joy to see transformations and to understand how colours ever so subtly change the way we look at things.

My answer to the second question? It’s pretty much the same as the first one. However, since Oreo has decided that we’re taking the scenic route today, let me first tell you why blue didn’t exist, and then why that statement is both completely true and blatantly false at the same time. Oh, and also lets start this walk.

“Sheesh, Oreo, stop pulling on that leash!”

As I look up at the brilliant blue Bangalore sky, I come back to our question. How did the ancient world not have blue when the sky is literally right above their heads?

Before I talk about that, though, let me clarify a linguistic tick which may cause some confusion.

What is colour?

As if reading my thoughts, Oreo suddenly jerks to a stop.

Actually, he has stopped to smell a particularly interesting plant, perhaps using his nose to sniff out a message from another dog.

In any case, since we’ve stopped, let me take this time to answer the question: What is colour?

We use the word “colour” to mean two different things. One meaning refers to the parts of the spectrum of light that the apes known as human beings can see, and the other refers to compounds that seem to be roughly in the hue of the light spectrum that we have names for.

You see, light is what we call an electromagnetic wave.

There are many types of electromagnetic waves, and actually, they are all the same, yet all very different. From radio waves to microwaves, electromagnetic waves are all parts of the full spectrum of electromagnetic radiation. A small portion of this is what we refer to as the “visible spectrum” – the part of the spectrum that is visible to us. Other animals can see parts of the spectrum that aren’t visible to us, and others still are limited to seeing only a portion of the spectrum visible to humans. Some animals can ‘feel’ parts of the spectrum as well as heat.

Now, the visible spectrum is divided into seven colours. Starting from violet on one end and going up to red on the other. Ultraviolet rays – aka UV rays – correspond to the wavelength beyond violet, while infrared rays correspond to the wavelength beyond red (and are also the ones responsible for heat).

When we are speaking in terms of this definition of “colour”, most of the colours we see around us are actually the parts of light that objects refuse to absorb. An apple looks red because it’s actually absorbing all the other colours and only reflecting red back at us. It’s like the apple is saying, “Nah, you can have the red light, I’ll keep the rest.” White things are objects that reflect all wavelengths back. Black objects are the opposite – they’re absorbing almost everything.

This is why we are often told to wear white in the summer, as the colour helps reflect infrared rays, thus literally pushing away heat. The opposite is true for black objects – they absorb heat, making them perfect for when you want to sweat that little extra bit. Just make sure it’s not too black. Especially not the blackest black.

What is the blackest black, you ask? Guess a digression is in order. Well, in 2014, a company called Surrey Nano Systems released a pigment called “Vantablack”, unofficially known as the “blackest black”, as it absorbed up to 99.965 per cent of visible light. While it has many applications, it is also extremely hard to work with, as any object painted with it becomes extremely hot very quickly. Vantablack is no longer the blackest black. A new pigment made from carbon nanotubes created at the Massachusetts Institute of Technology now holds that honour, absorbing 99.995 per cent of all light. There’s also Black 2.0, which was created as a direct response to Vantablack.

However, there is a story worth sharing about Vantablack.

This story about Vantablack features some colourful characters. A very well-known artist named Anish Kapoor (the same one who created the infamous bean sculpture in Chicago) struck a deal with the company to let him exclusively use the colour for his artworks only. This sparked a huge controversy in the art world. The idea of restricting a pigment to be used by only one artist seemed outright criminal to many in the art community. In response, another artist, Stuart Semple, created a colour called the “pinkest pink”, with a legal rider: it would be available for use to everyone except Anish Kapoor. Semple later went on to create Black 2.0, which comes with the same legal rider.

So I guess in this case, usable “colours” for Anish Kapoor mean everything but the pinkest pink and Black 2.0. Which reminds me, we need to go back to the meaning of colours.

Oreo tugs at the leash, clearly wondering why we’ve stopped for my impromptu physics lesson. Just a minute, I tell him, “This gets interesting.”

Going back to the two meanings of colour – as I’ve mentioned, colour is a result of the wavelength of light that an object reflects. How do objects do this though? How do they absorb some wavelengths of light while reflecting others? This is because of pigments. Pigments are molecules or complexes of molecules that absorb a certain portion of the spectrum, while reflecting others.

This is the other meaning of the word “colour” that we use.

The primary colours we were taught in art class (red, green and yellow) do not refer to the wavelengths but to these pigments.

If you combine all three of the primary colours wavelengths, you get white. If you do the same with colour pigments, you get a muddy grey or brownish colour depending on the base chemicals used in the pigments.

Now that we’ve taken a detour to talk about what colour is, let’s come back to my earlier claim: “Blue didn’t exist!” Now, while that’s only a three-word sentence, it also, like most things discussed in this chapter, has multiple meanings.

The first meaning of the phrase “blue didn’t exist” has to do with the wavelength of visible light corresponding to the colour blue. Saying that blue didn’t exist in that context would make no sense. Early humans could almost certainly see the colour blue, but did not name it as a distinct colour.

Which brings me to the second interpretation. The word “blue” did not exist. This is closer to what I’m referring to.

NOTE – This article was originally published in Scroll and can be viewed here