In a follow up to yesterday’s post, I wanted to talk about tetrachromats. Tetrachromacy is when someone has four opsins, instead of the regular three. Tetrachromacy can only occur in women, and is caused by having a fourth type of opsin that registers between the normal red and green. Tetrachromats are more likely to have colorblind sons (one of their X-chromosomes is missing the regular third opsin and instead has this fourth, so if their son gets that, he is missing the regular opsin and only able to see differences within the other two normal opsins), but not all women with colorblind sons are tetrachromats (they might simply have two of one of the regular opsins and another of another of the regular opsins on the X-chromosome or might have only 2 or less of the regular opsins coded on the X-chromosome). It is estimated that 3-4% of women are tetrachromats, which is markedly lower than the rate of colorblindness.
It isn’t that these women can see colors that other people cannot see; rather, they can see extra shades within the same color range we experience. This means that they can discriminate between very slight shade differences that other people could not. They may see up to hundreds of thousands of shades of colors that we could have no way of even imagining. Hopefully, this makes sense to you with what we talked about with opsins yesterday. It’s hard to imagine how much different the world might look with more shades than what we can see, but I bet it is incredible.
[Image Source]- Supposedly if you see something more than just colored circles in the above images, you might be a tetrachromat.