My friend told me that people with light-colored eyes (blue or green) cannot see as well during the day as people with dark eyes (brown). He says that it is because the blue and green eyes reflect more light away than the brown eyes do. He also says people with brown eyes cannot see as well in the dark (for some reason). This seems like a bunch of crap to me. Doesn’t the pupil absorb the light? What difference does it make what color the iris is? Does anybody know if this is true or not? Let me know what you think. Thanks a lot.
I’ve heard the same thing. I don’t know what the physical principle is, but it seems like there must be some evolutionary advantage to blue eyes. Certainly there seem to be evolutionary disadvantages to blue eyes - being more easily blinded in bright sunlight is sometimes mentioned (although I don’t know the physics behind that either).
The upshot is, there should be some lighting-related reason for eye color variation. I wish Cecil would answer this. Hey Cecil!
Then I wonder what my eye color(s) mean. They change from brilliant green to grey to hazel to blue, depending on a lot of factors. This is not just my imagination, as many other people have commented on the phenomenon. (could be our collective imaginations though).
I have damn good night vision, and can see as well as the next guy in the day, though I prefer to stay away from direct sunlight.
Cecil did a column on multicolored and changing eye colors. I don’t believe he mentioned differences in vision due to eye color though. I have one eye that is blue and another that is half blue and half brown. I’ve never noticed any difference in day/night vision between the two.
In terms of vision, the pupil ADMITS light, the retina ABSORBS it. (Of course the rest of the eye (including the iris) absorbs light too, but not as a function of vision. Your hair, skin, etc. absorb light, also not as a function of vision.) The only way I can see that iris coloration would affect vision is if it caused differential reflection within the cornea, was directly related to the transparency of the pupil (!) or the fluid that fills the eye, or was directly related to the efficiency of the retina.
All of these seem unlikely to me, which is to say I think your friend is full of it. On the other hand, statistical correlations might be discernible which would allow eye color to be used as a handy guide to the probability that a given person’s vision was non-normal in a given way, but if such correlations existed this would still not indicate causality (and that is an important distinction).
In terms of survival benefits, there are more things to consider than mere differences in vision. Eye cancer leaps immediately to mind, with light-eyed people supposedly being more susceptible. And this should be of little surprise, seeing that light eyes developed in the same latitudes as light skin tones, where the UV levels are lower. (It’s not that light eyes see better or worse in given lighting conditions, but the penalty for being more susceptible to UV is far less in the far north. Advantages? I dunno.)
All I can say is, I got blue eyes, and my vision sucks. It’s like 20/40 or so. But night vision? Pshaw! Got that covered. And, alternating each eye open/closed, I notice that one eye gives a more reddish tint to things, and one gives a more yellowish tint.
–Tim
We are the children of the Eighties. We are not the first “lost generation” nor today’s lost generation; in fact, we think we know just where we stand - or are discovering it as we speak.
According to the book “Racial Adaptation” light-eyed people tend to be better at recognizing shapes and dark-eyed people better at colours. There’s also a bunch of other stuff there about how light eyed people are better at seeing long distances and other stuff to which I didn’t pay much attention to.
If anyone is interested they can look it up in that book.