Colouring pencils
Image via Wikipedia

Disclaimer: If you already knew this stuff, I apologise, but I found it pretty cool.

Our eyes have three different types of cone cells that allow us to see a huge range of colours. Okay, so you knew that already, but I haven’t gotten to the good bit.

Televisions, computers, magazines and other visual media all exploit the fact we have those three types of cells to create the range of colours we see in them. They use three different pigments or three different lights, in various combinations, to do this. Hence the three “primary colours“. No, that wasn’t the good bit either.

Different animals have different numbers of cone cells in their eyes. Sea mammals (like dolphins) have just one type of cone cell, so can’t really tell colour at all. Most other mammals, except primates, have two types of cone cell. Most birds, and some fish, have four types of cone cells. Pigeons and butterflies are believed to have five types of cone cells. Stomatopods are thought to have as many as twelve different colour receptors!

Actually, some people (particularly women) are believed to have four types of cone cells. If ordinary people can see 1 million colours, they can see 100 million different colours.

But for these women, and most birds, butterflies and stomatopods, the three primary colours don’t always represent reality as they see it with their naked vision. You might show them a picture of a colourful flower on a computer monitor, but it is generated by red, green and blue dots, and so won’t look like the actual flower.

I wonder if the different species cone cells have evolved to help us find food and avoid predators, and if so whether you could match up the different spectral sensitivities of species’ cone cells with the colours of different plants and animals to determine if they evolved together.

Oh, the cool thing was the women with super vision. But, I think the rest of it is pretty cool also.

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