I used to think I had Ted Williams-caliber vision (a doctor said that, and it was memorable for a 10-yr old aspiring baseball player). When dreams of baseball stardom started to seem less likely, I began to think I’d make a good pilot. Though I’ve long since chosen a different direction, I still took pride in having a top-notch visual system.
And then I discovered at the age of 28 that I’m colorblind. How did that go undetected for so long? Well, it’s not that I can’t detect colors – I can differentiate and name them well enough – but when given a color blindness test like the one below, I fail miserably.
Can you read the number in this circle?
For most people, the number “74″ jumps off the page, distinct and obvious – but not for those who are color blind. I see a “21″, and someone with more severe color blindness won’t see any numbers.
Color blindness is most often due to missing 1 or more of the 3 different types of cells that detect colors (aka “photoreceptors”) found in a normal eye. Each photoreceptor is tuned to respond to a different wavelength of light, and your brain can interpret their responses by combining the information from each type of photoreceptor, ideally leading to the perception of a vast array of colors.
I’m likely short on 1 type of photoreceptor making me red-green color blind, but it didn’t take long to uncover a rationale suggesting that colorblindness could be an advantage!
In WWII analysis of aerial photographs, teams that included color-blind people were more successful. Color-blind individuals were able to detect unusual patterns in ways that normal-vision people couldn’t.
And more recently, researchers from the University of Calgary showed that color-blind monkeys are better at hunting insects. The monkey’s without color vision caught more insects, presumably because they could see through the insects’ camouflage. Evolutionary speculators have suggested that a group of hunters that contained at least one person who is color blind would be more successful, and so this trait might continue to be selected for in a portion of the population.
It seems that under some circumstances colors can be distracting and actually detract from our ability to see subtle variations in texture and brightness. While it may still be more desirable to have full color vision, the 10% of males who are color blind do have some consolation: We will never starve for lack of camouflaged insects.