TIL - Are There Colors Humans Can't See?

Yes. Not only that, but there's probably infinite number of them.

You might already know that color is not a characteristic of some item, but the result of effect that light with different wavelengths creates in our brain and eyes. So all colors are equally real or unreal. They are just a perception, not a physical property.

Number of colors that a human being can recognize depends on the type of system it has in the brain and eyes. Human brain on it's retina usually has 3 types of receptors that recognize red, green and blue by absorbing light and sending it back to the brain.

Every 12th man has only two types of receptors, and there are even people with only one type of receptors, that causes them to see much less colors.

Species with 4+ different cone cells

This condition is known as Tetrachromacy. Certain animals like goldfish, birds, reptiles, insects and some mammals possess four independent channels for receiving color information.

They are mixing four different primary colors (red, green, blue and ultraviolet light) to recognize the spectrum of light as a specific color.

In a distant past, this condition was common for most mammals. Due to evolution and genetic change, they lost two of their cone receptors.

In 2010, after 20 years of studying tetrachromat women, Dr. Gabriele Jordan found one who was able to recognize much wider spectrum of colors than people with usual three cone receptors.

Concetta Antico is an artist being awarded with this special condition. When she looks at a leaf here's how she describes it:

"Around the edge I’ll see orange or red or purple in the shadow; you might see dark green but I’ll see violet, turquoise, blue. It’s like a mosaic of color."

Certain species of butterflies have 5 independent cone cells. That means there is two extra primary colors compared to humans they can see. Imagining how beautiful that sunset would look like with butterfly eyes?

Mantis Shrimp

If we are keeping score, then this little fella is absolute champion when it comes to potential of color recognition. Mantis Shrimp lives in a warm and shallow waters and it has one of the most advanced visual systems out there with twelve different color receptor types.

At least two species have been reported to be able to detect circularly polarized light. Some of their biological quarter-wave plates perform more uniformly over the visual spectrum than any current man-made polarizing optics, and it has been speculated that this could inspire a new type of optical media that would outperform the current generation of Blu-ray disc technology

Researchers from the University of Queensland published a publication back in 2014, that the compound eyes of mantis shrimp could actually detect the existence of cancer in the body. Since they are sensitive to polarized light which shows differently in a healthy and cancerous body.

But before you start wishing to reincarnate as a Mantis Shrimp in the next life, there is a downside. According to this study, despite their magnificent eyes like no other species on earth, limited brain power makes it hard to handle so much more input. So compared to humans, they have much simpler system of combining and recognizing lights in the receptors.

The world they see is probably so much more different than ours, all we can do for now is try to imagine it.

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Sources: 1, 2, 3, 4, Images: 1, 2, 3

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