A couple of recent threads got the thinking about this. Is it possible for a human to have color blindness to the point of seeing NO color at all?
Do we know if there are animals who see no color? Well, let’s limit that to mammals for now.
Yes. The condition is known as achromatopsia. Here is a personal account of what it is like by a person who suffers from it, and became a vision scientist.
Are there animals that can see, but do not see color? I would say there almost certainly are, but I can’t name specific species offhand. If an animal had only one type of light sensitive cells in its eyes it could not distinguish colors. To see colors requires a tlesat two types of cell, that respond to different degrees to light of different wavelengths.
Missed edit window:
That is meant to read:
To see colors requires at least two types of cell, that respond to different degrees to light of different wavelengths.
There are also people who have lost color vision late in life - Oliver Sacks talks about one (a painter!) in “An Anthropologist on Mars”
My stepfather claimed to see only black and white. If the colors of the cars he bought were any indication, I can believe it.
Yes. Many mammals have only one kind of cone cell in the retina, and are monochromats. These include marine mammals (whales, dolphins, seals, sea lions, and walruses), as well as some nocturnal primates (galagos and night monkeys), carnivores (raccoons and kinkajous), rodents (hamsters), and bats.
Most mammals seem to be dichromats, with two kinds of color receptors, and have limited color vision. Old World monkeys, apes, humans, and female (but not make) howler monkeys are unusual in having three color receptors. (However, we are partly color blind compared to most other vertebrates, which have four.)
Does that mean that other vertebrates can see colors that you humans can’t see?
Dolphins, by the way, (and perhaps other marine mammals) have eyes specifically adapted to be able to focus well both under water and in air. In land mammals, focus is done primarily by the cornea (since there is a high refractive index there, between the cornea and the air), with the lens simply supplying the fine-tuning for distance. Under water, this doesn’t work at all. AIUI, focus is largely done by the lens, with other special adaptations as well – also to allow the eye to function well in air also.
Adaptive Features of Aquatic Mammals’ Eye (PDF), Alla M. Mass and Alexander Ya. Supin, The Anatomical Record 290:701–715 (2007). I think this report also touches tangentially on color vision in marine mammals.
My mother was completely colorblind. She could not tell black and white TV shows from color shows. I have partial colorblindness. Grey/green looks the same to me. I always have to have a girlfriend help me shop for clothing.
That occurs when someone has brain abnormalities, but it can also occur at the retinal layer. People can also have just rods and L or M cones (black and white vision), rods and S cone (B&W, poor acuity because S cones are only 8% of the total and also don’t occur in the very center of retina. I have met two of these people), just rods (B&W, poor vision, vision extra poor in normal light), or perhaps just 1 cone type and no rods (I don’t know if this has ever been diagnosed).
All howlers are trichomats. Other NW monkeys like squirrel monkeys have always dichromatic males, and females who either have 3 and 2 cones depending on their genes.
Hamster - at least the Syrian hamster has two cones, according to an abstract (it’s a dissertation and I can’t get at it). It suggests that it was previously thought otherwise. Mice, rats, gophers, guinea pigs, and squirrels all have two cones. African giant rats have only one, either M or L.
At least some megabats (the cute ones) have two. The flying foxes, for one. They need it because they hunt for fruit mostly instead of insects.
Many of these species has a short wavelength cone that goes further into the UV range than humans.
Good review cite for many species: Jacobs, 2009 Phil. Trans. R. Soc. B, a big part of this one is also marsupial and monotreme genes. They’re weird.
And of course, some species of non-mammals, like those creepy, creepy, mantis shrimp, have 12-20 or so color receptors depending on species, along with polarization receptors. The better to kill with.
Yes. Birds, for example, can see UV. It’s been found that in some species in which the male and female appear to be the same color to our eyes, the male is actually brightly colored in UV (while the female is not). We can’t even imagine what the world looks like to a bird, any more than a color blind person can imagine what “red” looks like.
Oliver Sacks also wrote “Island of the Colorblind” which is an excellent read.
Human Tetrachromats see more colors than us mere trichromats.
Scientists find woman who sees 99 million more colors than others