Color me fascinated at learning today about the condition (or blessing, as it were) of tetrachromacy. I cannot wait to tell my students about it.
Now, we all know about color blindness and the fact that it is most prevalent in men. In fact, it is quite probable that you know a man who is color-blind. I do. To a minor extent, I am one of them. Call it a perception-reducing malady, or call it just a minor inconvenience, I struggle with some color gradations on the spectrum. So far in life it hasn’t been a problem (I can see the color money quite well, thank you very much).
There is a much less known perception-enhancing condition and one that is genetically based, called tetrachromacy. And from what I can tell, we didn’t know about it until the 1990s.
Here’s the rub, and the pay-back if you will: it exists only in – wait for it – women. Thaaat’s right: Only women, and at that, only about 5% of them.
Think here of the digital camera and the means by which its sensor works. The sensor is the heart of a digital camera. Sitting behind the lens, it converts lights rays into electrical signals for further processing inside the camera. A sensor contains pixels of the three primary colors: Red, Blue and Green. When light is allowed to fall on these pixels, by means of the shutter release, the electrical signal corresponding to the correct combination of colors (according to the scene) is generated.
You know the drill: The more the pixels on a sensor, the better details we get in an image. That is why people want a camera with the most pixels possible (my collection of digital cameras have anywhere from 16 to 25 megapixels). Mind you, we don’t need more than about 6 MP, but camera manufacturers are keen to sell us as many as they can.
What does this have to do with tetrachromats? Well, a normal human eye has a set of three color-detecting “cones.” You guessed it: They are evolutionarily disposed to pick up on Red, Green, and Blue. Each cone set can pick up about 100 colors. When all three are combined together by the brain, a human can see about 1 million different unique shades of color.
Turns out, tetrachromats have a fourth cone cluster that exists on the color spectrum between red and green. This extra set of cones adds in another 100 potential shades of color and boosts the potential combinations up to 100 million unique shades! Whereas the average person sees 5-7 shades of color in the rainbow, a tetrachromat would see 10 or more.
Ironically, the easiest way to find a tetrachromatic woman is to look for a colorblind man. The same genes that cause color blindness in men – by providing an over abundance of green and red cones – are linked to the extra set of cones in women. The mothers of colorblind men are dramatically more likely to have tetrachromatic mothers.
You learn something new every day.
Color me fascinated!
