CHIMPANZEES, like humans, can distinguish among colors that other mammals cannot see.
What observers see in a Kandinsky reflects the properties of the paints, the nature of the illumination, and the color vision system of the viewers.
Image: Geoffrey Clements Corbis (painting); Bob Elsdale Corbis (chimps)
In Brief
- The color vision of humans and some other primates differs from that of nonprimate mammals.
- It is called trichromacy, because it depends on three types of light- activated pigments in the retina of the eye.
- Analyses of the genes for those pigments give clues to how trichromacy evolved from the color vision of nonprimate mammals, which have only two kinds of photo pigments.
- The authors created trichromatic mice by inserting a human pigment gene into the mouse genome. The experiment revealed unexpected plasticity in the mammalian brain.
To our eyes, the world is arrayed in a seemingly infinite splendor of hues, from the sunny orange of a marigold flower to the gunmetal gray of an automobile chassis, from the buoyant blue of a midwinter sky to the sparkling green of an emerald. It is remarkable, then, that for most human beings any color can be reproduced by mixing together just three fixed wavelengths of light at certain intensities. This property of human vision, called trichromacy, arises because the retina the layer of nerve cells in the eye that captures light and transmits visual information to the brain uses only three types of light-absorbing pigments for color vision. One consequence of trichromacy is that computer and television displays can mix red, green and blue pixels to generate what we perceive as a full spectrum of color.
Although trichromacy is common among primates, it is not universal in the animal kingdom. Almost all nonprimate mammals are dichromats, with color vision based on just two kinds of visual pigments. A few nocturnal mammals have only one pigment. Some birds, fish and reptiles have four visual pigments and can detect ultraviolet light invisible to humans. It seems, then, that primate trichromacy is unusual. How did it evolve? Building on decades of study, recent investigations into the genetics, molecular biology and neurophysiology of primate color vision have yielded some unexpected answers as well as surprising findings about the flexibility of the primate brain.
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20 Comments
Add CommentI think it would be awesome to be able to see in ultra violet and infra red. There's just so much out there that we don't see.
Reply | Report Abuse | Link to thisI recall that some eye operations result in individuals becoming able to "see" ultra violet. Presumably the same mechanism works in these cases.
Reply | Report Abuse | Link to thisHow does blue green color blindness fit in to the evolutinary sequence? Is it a processing error, early or late, beneficial or harmful? What are the implications/possibilities for correcting/expanding human vision?
Reply | Report Abuse | Link to thisCould the regular mosaic patterns needed to create multi-modal color vision (e.g. trichromatic) arise from a mechanism like the "spots" in other animals? Leopards, dalmatians have random spots. Like fingerprints, each animal has different spots, but as a whole have consistent mosaics.
Reply | Report Abuse | Link to thisDifferent breeds w/i the same species (cats, dogs) have different markings. Different individuals will have patterns (mosaic or flat) related to, but somewhat random from their ancestors and environmental stress.
Can these mechanisms also apply to the development of mosaic patterns, uniform enough to allow trichromatic vision in some female new world primates, but not others?
The separation of the pigment coding sequences (on X, and on 7) are a definite blow for ID (as if it needs any more!) - what designer would create such a hodgepodge? That's in addition to the extremely poor optical design (all the support infrastructure for the retina is between the lens and the cone/rod cells!) that reduces the available effective illumination and resolution.
Reply | Report Abuse | Link to thisI suppose human eyes aren't so irreducibly or superbly designed after all!
If we accept that our primate ancestors were more likely catfood than hunters (another myth, just like ID), being able to discriminate a big yellow-brown striped or spotted carnivore hiding behind a green bush over a distance may have been a significant survival helper.
Reply | Report Abuse | Link to thisSome people can see a bit into UV or IR. About 1 person in 1000. It's not very far, but if something is at about 130F and large they can see it in complete darkness. I have also made drawings of things that people can not see, [Gas jets in comets and some details in flowers] but that showed up on UV sensitive photographs. Most peoples retina are sensitive to ranges outside "normal" vision, but have pigments in the lens that block it. Some people are missing that pigment naturally or due to lens replacement.
Reply | Report Abuse | Link to thishave seen an 18year old who could go as low as 340nm he saw those colours as we see indigo
Reply | Report Abuse | Link to thisI wish they united efforts with Kimberly Jameson and Susan M. Highnote who wrote "Richer color experience in observers with multiple photopigment opsin genes" (Psychonomic Bulletin & Review 2001, 8 (2), 244-261). I think they will finally discover why women have so many names for colors where men see just one hue.
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Reply | Report Abuse | Link to this~
I apparently have unusual vision. I was a commercial pilot and when taking the vision tests the Flight Surgeons had some interesting things to say.
Would anyone have an explanation for me, as I have been curious about it for many years but have never heard an explanation.
1) My vision (used to) test as 20-5, and I could easily read newsprint from across a room (makes for a neat party trick) . The Docs told me that is not unheard of but very rare, that usually only pro baseball pitchers have that visual acuity.
2) I can read the numbers on the color blind test charts that no one is supposed to be able to see. The Docs told me (after making me read several of them to make sure that I was not cheating by having been told ahead of time what the numbers should be) that is why they were included, -to prevent people from claiming to be reading something that could not be detected by anyone.
3) When I look at rainbows I see many "bands" of colors, with about 1/4 of the bands on the outside of what anyone else can see (I assume I am seeing into the UV and IR). But what is up with the "Bands"?
After reading this article, I had a "Eureka!" moment and thought that maybe the explanation is that I have lots of extra cones in my eyes (explaining the 20-5 vision), and the cones are of more varieties than the S, M & L cones mentioned, perhaps some extra short Shorts, some Shorts, some longer Shorts, and some short, medium & long, Mediums and likewise some short, medium & long Longs (thus explaining the "Banding" and extra wide rainbows I see)
But enough of my self diagnosis, does anyone know what is up with my eyes?
BTW - I am long retired from flying, and I have noticed that my visual acuity is now slipping and it has gotten so bad that I was afraid that I might flunk the eye test for the automobile drivers license. On my last DMV eye test things seemed quite poor to me and I asked the Lady at the DMV if I had passed it. She said: "Oh Yes, you have perfect 20-20 vision." My word, do I feel sorry for people that go through life with this lousy 20-20 vision I am down to now. No more spotting other aircraft from 300 miles away for me.
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I think few realize that we as humans can have traits such as visual acuity and percetion of colors within and outside the normal spectrum. This, of course, involve selective breeding.
Reply | Report Abuse | Link to thisSome 3% of women have a fourth cone that allows them to see up to 10 million colors; although this has yet to be proven. It has been shown, though, that some of the sons from these women suffer from red-green color-blindness.
I am not an expert in animal husbandry so I can not say much, but I tend to believe that it would be difficult to create superior traits without some disadvantages being passed on as well. Such as the example I gave above.
Can the authors add anything on this fourth pigment system?
Reply | Report Abuse | Link to thishttp://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2278766
The articel says that only a subset of female New World monkeys have trichromatic vision. However I'm currently reading The Making of the Fittest by Sean B Carroll. In Chapter 6 he says that Howler monkeys alone amongst the New World monkeys are trichromatic. Which is correct?
Reply | Report Abuse | Link to thisDoes anybody understand which 3 colors we Old World primates have as primary color cones? I see R-G-B and Y-G-B as possibilities from this article. One of the charts even shows R-G-Y. ???!!
Reply | Report Abuse | Link to thisI got interested and started researching: http://en.wikipedia.org/wiki/Color_theory
Reply | Report Abuse | Link to thisInteresting, but I wonder where they got the New World/Old World Split at 150 mya. Primates didn't begin radiating (according to fossil records) until 65-55 mya and most experts believe the New World Monkeys split from Africa (via massive vegetative rafts) about 40 mya, this may change the timeline and point toward parallel evolution of trichromacy.
Reply | Report Abuse | Link to thisCharles Darwin, commenting on the human eye in his book, Origin of the Species (Chapter VI - Difficulties of the Theory): " To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree. "
Reply | Report Abuse | Link to thisAs somebody reasonably versed in the matter of color perception I read the article with interest and learned a number of facts new to me. However, I was surprised to find no speculative comment as to the nature of the added dimension of color vision. What do the findings imply about the fundamental nature of color? Does the implantation of the human L-type pigment gene only result in a new cone type or are the post-receptoral retinal layers also changed? Presumably, this can be determined. What about cell types in the lateral geniculate nuclei; does their number change? What might be the mechanism by which the mice with L and M type cones in their retinas are able to discriminate mid- to long-wave radiations?
Reply | Report Abuse | Link to thisIn the original article in Nature that I consulted trying to find some answers the last sentence points to additional genetic changes that refine the downstream neural circuits & could then follow over many generations. What do such changes add to the discrimination abilities apparently already existing in the retina?
As somebody reasonably versed in the matter of color perception I read the article with interest and learned a number of facts new to me. However, I was surprised to find no speculative comment as to the nature of the “added dimension” of color vision. What do the findings imply about the fundamental nature of color? Does the implantation of the human L-type pigment gene only result in a new cone type or are the post-receptoral retinal layers also changed? Presumably, this can be determined. What about cell types in the lateral geniculate nuclei; does their number change? What might be the mechanism by which the mice with L and M type cones in their retinas are able to discriminate mid- to long-wave radiations?
Reply | Report Abuse | Link to thisIn the original article in Nature that I consulted trying to find some answers the last sentence points to “additional genetic changes that refine the downstream neural circuits … could then follow over many generations.” What do such changes add to the discrimination abilities apparently already existing in the retina?
I believe blue-green color blindness arises exactly the same way as red-green; that is, a mutation in the short-wavelength receptor gene. It doesn't really fit into an "evolutionary sequence" because it is not common or conserved.
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