I was reading up the article about traffic lights and Colourblind people when I recalled a story relayed to me by a friend. Yep a bad start already, I know. It was told to him by an ex-SADF soldier during the border war who said that he had been a spotter in helicopter patrols because, being Colourblind, he could pick out camouflage from background foliage more easily.
I’ve heard that traffic lights’ red and greens are designed to be different shades so that you can tell them apart (not that I noticed) and vaguely remember reading from an online source about a study linking colour blind animals to some selective pressure.
So is there an advantage to being Colourblind? If so it a learned skill to help one function in a three tone world,or is it intrinsic to the biology? Or is it just more lies and Internet rumours?
The military has been known to mix colorblind people into teams of non-colorblind photo analysts, so there is an element of truth to what you heard.
That said, I don’t know if I would call it an evolutionary advantage. A colorblind person’s inability to distinguish certain colors sometimes allows their eyes to avoid getting fooled by certain types of camouflage. This doesn’t give them some kind of super ability with respect to detecting camouflaged things though, and it only works in certain circumstances. Colorblind people will also miss things that a normally sighted person can easily see.
For example, let’s say you paint a tank in two different colors (picking colors that a colorblind person has difficulty distinguishing). A normally sighted person would see the camouflage pattern and might mistake the tank for an underbrush pattern or whatever the camouflage is designed to be. A colorblind person however can’t distinguish the two different colors, and can’t see the camouflage pattern at all. They only see the tank. It’s not that the colorblind person sees “better”, it’s that they can’t see the part that fools the eyes of a sighted person.
Pick different colors though, and the colorblind person might be able to distinguish those and would be fooled by the camouflage pattern. Colorblind folks aren’t universally better at avoiding camouflage.
For general spotting and scouting types of things, the military prefers people with full sight capabilities.
Forgot to answer the second part of the question. Your eyes have different types of cells called rods and cones. Rods see black and white (they give you your detail vision) and see in low light conditions. The cones see colors. Normal people have three types of cones. Colorblind people are missing one (or more) of the types of cones.
It’s purely biological. You can’t train yourself for it.
It depends on circumstances. Different things will be obvious to people/creatures that have various forms of colorblindness that are harder to see with full range vision. I recall reading about a species of monkey that has several different kinds of color blindness as a normal feature of the species; apparently it helps them with hunting fruit & seeing threats, since what blends in for one monkey will be obvious to another.
Not that I have ever been able to deduce. My Daltonism rendered me unqualified to do several types of very lucrative jobs, caused my poor mother to have to sew numbers into my clothing so I didn’t walk out of the house looking like Bozo the Clown, and earned me many outraged honks and ire by other drivers at traffic lights. I failed my driving test twice in high school before I managed to figure out that the green light on a traffic signal is usually on the bottom. So no, can’t see any advantage to it at all.
This probably works mainly with human-devised camouflage patterns. Camouflage that occurs in nature is most likely selected to work for both animals with full color vision, such as birds, and those with poor color vision. So there is likely little if any advantage under natural conditions.
Some primates (Old World monkeys and apes, and a few New World Monkeys), unlike most mammals, have good color vision (although not as good as most vertebrates). This is most likely an adaptation for detecting brightly colored fruits.
Male howler monkeys are dichromats (having two color receptors), and have the equivalent of one of the common types of human color blindness. Female howlers are trichromats (with three receptors) and see colors as well as humans. However, I am not aware that troops derive any particular advantage from this.
Color blindness affects the cones but does not necessarily result in an increased number of rods. Do you have a cite that color blind people in general have better night vision?
My wife and I have a rule. If she does not pick out my clothes when we are going out she can not complain about what I am wearing. Before this arangement I often heard “you are not wearing that shirt with those pants are you”.
And it is not an advantage in my profession. In doing water tests there are some test that I can not do because the titrating involves going into a color I can not see well, so I have to sort of guess.
Which tests? All the titrations I remember go from clear to colored - even if you can’t distinguish the color, can’t you tell that the solution has darkened?
Is color-blindedness know to be genetic? Could it be a developmental issue?
My color blind brother in law was very successful as a hunter. He could spot brown rabbits or the light gray the deer adopted in Pennsylvania winters better than most of us.
Many predators have limited color vision. I am not sure how they determined it, but dogs largely see things as blue and yellow. This makes it easier to spot movement of something colored much like its background. It is easy to see how a meat eater might be better off with limited color vision. Color is more important to vegetarians.
Speculation: We have evolved little since our hunter, gatherer days. Would a population of them eat better with a range of color vision among them?
I am not aware of any correlation between carnivory and colorblindness/color vision. Dogs, like most other mammals, are dichromats, with two color receptors, which limits the range of colors they can distinguish. But deer and other mammalian herbivores also have poor color vision. Avian carnivores like hawks have color vision as good as that of most other birds.
Most vertebrates, including fish, reptiles, amphibians, and birds, are tetrachromats, with four color receptors. It is assumed that mammals lost this capacity in the early stages of their evolution because ancestral mammals were primarily nocturnal. Color vision is of limited utility at night. Even today, most mammals are primarily active at night.
As mentioned above, some primates, including Old World Monkeys, apes, and humans, and a few New World Monkeys, re-evolved a third color receptor. This is probably an adaptation for locating fruit, which was already brightly colored so birds could find it.
I’d dispute this assertion.
Roughly speaking, there are three main defense strategies for prey:
a) run awayyyyy
b) blend in
c) be highly visible to advertise other means of defence (or bluff them)
Ignoring a) where colour doesn’t play much of a role, I’d say colour sight is pretty central in the process of differentiating between the green tree frog that prays very hard b) will work ; and the violent red, more poisonous than a Sicilian mother in law tree frog who went all in with c).
There are many tests in water-quality titration analysis where the end-point is determined by a change from color to no color, no color to color, and one color to another.
My brother, who has severe Red-Green color deficiency, had trouble in his high-school chemistry class when they were required to do a titration from a clear solution until a pale pink color appeared. His instructor walked past and noticed that his solution was bright red, and yet he was still titrating more reagent into the dish. He was completely oblivious to the color which was developed in the reaction.
I have relatively “normal” color vision, and was fascinated by his condition. It is my understanding that color deficiency is, in part, caused by a faulty gene (or set of genes) on the “X” chromosome, meaning that color deficiency tends to plague males more often than females. Color vision is obviously a complex biological process, controlled by many factors, but it does seem to have an hereditary component.
This is interesting; I had no idea someone might not see anything; I assumed they would just see a darkening grey.
I do know red-green color blindness was the classic example of recessive sex linked mutation, but I was wondering if any colorblindness might result from lack of adequate visual stimulation during development.
Huh. I guess I don’t know that much about wet chemistry.
Thank you for the replies.
I’m not sure why you would think there are fewer cones in color-blind people. The problem usually is that one particular kind of receptor is defective, not that it is absent.
The Wikipedia article on color blindness provides some good background, and is worth reading if you are unfamiliar with its basis. There are several different kinds of color blindness in humans, owing to various genetic (usually) causes.
Yes, but cones are the detail cells. Rods see coarsely. They are better at seeing contrast, though.
What matters is absolute number of cells, not rod/cone ratios. Losing a cone type will not increase your number of rods. In addition, losing your “red” cones will cause them to be replaced by “green” cones or vice versa; the absolute number of cones is not decreased. “Blue” cones are rather sparse on the retina, I’m not sure what happens with tritanopia but it’s pretty rare.
I’m pretty certain it’s: Howler monkeys are the only trichromats among NW monkeys. Most other species are dichromats. Some species have 3 types: dichromat males, dichromat females, and trichromat/polymorphic females who can see “humanlike” colors.
I don’t know either, but I could speculate it would have some effect on the Purkinje effect. I cannot fathom how this would actually appear, though, and whether colorblind people would be at an advantage or disadvantage here.
The types were there is a missing red or green cone, or a shifted but not missing red or green cone are genetic. They are on the X chromosome and thus much more common in males, as females need to inherit two copies of the gene to have an effect. Blue cone defects are much rarer (<1% for both males and females) and have no sex differences because they are not on a sex chromosome (chromosome #7 IIRC).