Color Isn’t Real

I tell this to my college-level design students in the first class. They have been well-trained in color theory and are about to go into the professional world, where every color has meaning. To humans, that is.

 

I don’t say this to make a smug scientific point, but rather to emphasize a subjective way of looking at the world in front of us, both in terms of intersubjectivity of humans, and also between species themselves. Our experience with color seems so natural, so obvious, that we rarely question it. But the truth is, all species, including humans, perceive the world only as our biology allows us to see it. 

The Spectrum is Real. Color is Interpretation

What is real are the trillions of photons all oscillating at different frequencies. Our brains detect these different oscillating frequencies and map them out to be what we perceive as colors. 

 

Humans have trichromatic vision, with color receptors (cones) in our eyes that can “see” the colors blue, red, and green based on their wavelength. We can see yellow, purple, orange, and all the other colors from a combination of those three receptors. 

 

However, this means that we only see a tiny slice of the electromagnetic spectrum, specifically the visible spectrum, which ranges from 400 to 700 nanometers (nm). Outside of that narrow range, there are also gamma rays (<0.01nm), X-rays (0.01 – 10nm), ultraviolet (UV) (100-400nm), infrared (700nm to 1mm), microwaves (1mm to 1m), and radio waves which partially overlap with microwaves from 1mm to 1km.  

“Electromagnetic Spectrum” image sourced from GeeksforGeeks

Within the visible spectrum, blue or violet corresponds to photons that oscillate in the 400-500nm range, green in the 500-565nm range, yellow in the 565-590nm range, orange in the 590-625nm range, and finally red in the 625-700nm range. So, what we perceive as blue, red, green, and yellow are just different wavelengths of visible light that our cones can detect, which are processed by our brains to see as color.

Bees Don’t See Red, But They See More

Bees don’t see red at all. Like humans, they have trichromatic vision, but theirs is different. They have sensors for blue and green, not red, but they also see in the ultraviolet range (100-400nm). 

Many flowers have evolved visual patterns in the UV spectrum that act like landing strips or target guides for pollinators such as bees; patterns that are completely invisible to us unless we use special cameras. So while a daisy may look plain white to us, a bee sees vibrant colors, like a well-lit runway inviting them to come in for a landing.

“White Gerbera Daisy in Ultraviolet Light” by Brett Zimmerman

This inability of bees to see red is why most red flowers are pollinated mainly by birds that have tetrachromatic vision, which enables them to see UV, blue, green, and red. Still, some red flowers are also visited frequently by bees. Why? It’s because those red flowers also emit UV that bees detect, inviting them to visit despite the red they don’t see.  

Reindeer in the Arctic: Seeing What Snow Conceals

Another striking example of ultraviolet perception comes from reindeer, who live in the Arctic, where the landscape is covered in snow and bathed in diffuse light for much of the year. 

Reindeer are dichromats, and mainly see in the shorter blue wavelengths, but not red, which is why a hunter’s orange vest doesn’t stand out to them like it does to us. However, they also see in the ultraviolet light range, which helps them survive. This ability is aided by a second type of receptor called rods, which work exceptionally well in the low-light conditions of the Arctic.  

Reindeer eyes are adapted to detect UV wavelengths around 320–400 nanometers, which is also the wavelength of light that bounces off lichen (their primary winter food), urine trails, and even the fur of predators like wolves. In visible light, as we see things, all of this blends into the snowy background. But in UV, these features stand out in high contrast, like hidden ink under a blacklight.

This ability gives reindeer an evolutionary advantage: they can find food, track herd members, and detect threats in a world that looks nearly featureless to us.

Reindeer vision in action: Lichen absorbs ultraviolet light and appears dark against UV-reflective snow, making it easier for reindeer to spot food and predators in Arctic conditions.

Image credit: Nathaniel Dominy / Dartmouth College via EurekAlert!

Zebrafish Light Their Murky World in Near-Infrared

A case study on the other end of the spectrum is the zebrafish, which is a small freshwater creature that lives in murky rivers and flooded rice paddies. Unlike bees, which can see shorter wavelengths than we can, zebrafish may be able to see just beyond our visible spectrum, into the longer wavelengths in the near-infrared (NIR) range. Scientists have discovered that zebrafish respond neurologically to light in the 750–850 nanometer range, which are frequencies we can’t see, but are abundant in their freshwater environment, especially when visible light is scattered by sediment suspended in murky waters.

Zebrafish (Danio rerio)—commonly used in vision and neuroscience research.

Image credit: Photo by Azul, public domain (CC0), via GoodFreePhotos.com

This near-infrared sensitivity likely gives them a visual edge in muddy or low-light conditions. What appears dull and brown to us would have contrast to them, revealing predators and prey. Their world is tinted not by red or blue, but by light we can’t even perceive. Another example of an animal with a unique ability to detect wavelengths outside the visible spectrum, giving them an evolutionary advantage that helps them survive. 

Final Thoughts

The world is made of electromagnetic radiation spanning a vast spectrum of wavelengths, of which we only “see” the tiniest portion. Even then, what we see is just what the cones in our eyes can detect, and how our brains process it. This means that color isn’t a fixed property of objects, as we are taught with language, such as “the green chair,” but rather, a subjective experience that is species-specific and often tied to ecological need and enhanced by evolution. Therefore, every organism on Earth “sees” its own version of reality, not reality itself, since the reality of vision and color is entirely subjective.