You are most likely a trichromat, although dichromats are common enough. But only a few are tetrachromats.
How many different kinds of cones in your eyeballs? Most people have three kinds (“tri-“, while colorblind people might have only two (“di-“). But apparently there are some folks who have four — “tetra”. And so they can see far more different shades of colors than the rest of us.
Scientists say they have actually found such a person. Which is, of course, like much of scientific discovery, cool.
And what would our color theory look like if we all were tetrochromatic?
We say that color is made up of three components, but RGB only covers a most of the colors you actually experience. It does not cover all. This image shows the colors covered by the major RGB models (sRGB is the common one). Compare it to the horseshoe-shaped arc of actual colors people (tricromats presumably) actually see. (The full article on color spaces is interesting too.)
This basic approach to color reproduction is pretty old now, and it does pretty well. But if we were (say) red-green colorblind as a species, we would have a different approach to color (it would be much cheaper I’m sure). If we were tetrachromatic would our stand model be based on three colors? Or would we have found that far too primitive an approximation?
What if we could see in a broader range of wavelengths? How many colors would it take to model that? Or would it be three somewhat different colors?
Much of what we take for granted is just biological happenstance. It’s worth remembering here, where it’s fun. It’s also worth remembering elsewhere, where it has real moral implications.