9 ms·

The red and green specialists: why human colour vision is so odd

77 points by pablode 9y ago

luk32 9y ago
So are trichromatic people colorblind to tetrachromats? BTW. Wikipedia says that trichromatism was normal for mammals in the past, and then they lost one or two cones, which would suggest a different development path. The article does not touch on this. Or did distinct cones were reduced, and then one of them split into two again? It's also interesting whether chemical structure of cones is similar. I guess I gotta do some research on my own.
dingo_bat 9y ago
https://imgur.com/a/jdVqE https://imgur.com/a/jdVqE Boy that's some next level webpage design!
- pablode 9y ago
  Url is optimized for mobile (and without the banner). This one is more suited for desktop use [1]. [1] https://aeon.co/ideas/the-red-and-green-specialists-why-human-colour-vision-is-so-odd https://aeon.co/ideas/the-red-and-green-specialists-why-huma...
  - dingo_bat 9y ago
    Interestingly, this link works properly on both mobile and desktop. Wonder why the original link is even needed.
    - rhn_mk1 9y ago
      To avoid loading the images with the page. They appear later through a JS mechanism (to the disappointment of noscripters).
nadohs 9y ago
Incredibly stupid experiment. As someone who is red-green color weak, just as 10% of the male population is, I feel insulted by the implication of this article and the obvious glossing over the fact that not all humans see green/red very strongly. This is lazy science, seriously asking people to differentiate between images of apes that want to mate? It made no sense, you basically proved that some people are colorblind... ok. Did you plan and write this over a weekend? Why did you even bother?
- vanderZwan 9y ago
  As a fellow colour-blind person (protanomally): you're reading implications that are not in the article.
  - nadohs 9y ago
    ...
rowyourboat 9y ago
> Instead of having good vision, dogs, horses, mice, antelope – in fact, most mammals generally – have long damp snouts that they use to sniff things with. It is we humans, and apes and monkeys, who are different. What a load of bull. Dogs and wolves eyes are facing forward, as do cats', owls', jumping spiders' main eyes, and generally those of most hunting predators. Eyes facing forward is good for depth perception and judging speeds and thus hunting, a bigger field of view is good for detecting threats from any and all directions and thus for prey animals. The location of the eyes depends mainly on where the animals sits on the predator<->prey scale. Apes tend to be apex predators, thus the predator eye location.
- geon 9y ago
  Dog have worse resolution, color perception and depth perception than humans. http://servicedogcentral.org/content/node/391 http://servicedogcentral.org/content/node/391
  - rowyourboat 9y ago
    I was contesting the statement that forward-facing eyes somehow make us special. They don't. They are a trait we share with most predators.
    - geon 9y ago
      The eyes of dogs are less forward facing than on humans.
    - woodandsteel 9y ago
      But our primate ancestors who originally evolved forward-facing eyes were not predators. Makes much more sense to think it was to help in swinging from limb to limb in trees.
- simoom22 9y ago
  All primates having forward facing eyes, but lemurs and sloths are only apex predators if you're a berry.
vanderZwan 9y ago
As a colour-blind person, this article both makes sense to me, and at the same time it doesn't. I have often wondered why human colour vision is not evenly distributed across the spectrum of visible light. This seems like a decent enough model for why that might be the case. However, that makes it very peculiar that there are so many people with colour-blindness like me, especially if it would be such a strong evolutionary advantage. One would expect selection pressure to have removed those genes from the gene pool by now. My own pet hypothesis is that it has to do with humans being a social species. For us, individual specialisation has much bigger evolutionary benefit, since it is shared, and a lower evolutionary cost, because other members of the group can compensate for shortcomings. To give an overly simplified "economic" model of it: when we collaborate properly, the net performance of a group is not the average performance of all members, but the sum of the maximum performance of individuals. So back to colour-blindness. It is fairly well-established that dichromatic colour-blindness helps see through certain types of camouflage. In a hunter/gatherer society, having one member of the group who is good at spotting prey animals (or dangerous predators, for that matter) is a huge advantage for the group, and your friends can assist you with getting ripe berries.
- lucozade 9y ago
  There is an alternative hypothesis. That it's just an evolutionary accident. Possibly it's a side effect of some other factor that is significant. I mean, we get a lot of evolutionary traits because of bias through natural selection. But there's probably not much reason to lose a trait if there's no selection pressure to. It still may happen,of course. It's possible we'll all have brown eyes some time down the road. But it's not obviously because of natural selection.
  - vanderZwan 9y ago
    Of course, there may be no strong selection pressure against it. But the odd bias for red-green distinction has been there from the earliest primates, suggesting there is a strong selection pressure in favour of specialising in red-green hue distinction. This then goes directly against having no ability to distinguish so many green and red hues. Well, unless the only genetic way to maintain this bias includes a risk of colour-blindness, but I kinda doubt that. Tangent: actually, eye colour is very strongly influenced by natural selection. Specifically, IIRC it's one of the prime examples of social and/or sexual selection pressure being stronger than other pressures, precisely because it has no other survival advantage/disadvantage associated with it otherwise. Since social success is essential for individual survival in our species, being discriminated against for ethnicity in general is a selection pressure (and before I am misunderstood: evolution is an amoral context-optimiser and Social Darwinism is one of the worst perversions of a scientific theory ever).
bawana 9y ago
The article would have been more interesting if they addressed the peculiar fact that half of all women and all of spiders are tetrachromats. It would be interesting to add the cones for additional frequencies into a genetically engineered monkey. I can imagine that having vision in the infrared and UV would make animals better predators (like Predator)
- sethammons 9y ago
  Not half of woman. More like 2%. https://www.snopes.com/politics/medical/tetrachromacy.asp https://www.snopes.com/politics/medical/tetrachromacy.asp
- vanderZwan 9y ago
  And then there is the mantis shrimp with 12 different photoreceptors[0] As for genetically engineering an extra cone, they did that with mice, mainly to address the chicken-and-egg question: if you get an extra cone, does the brain learn to see extra colours? It seems like it would[1]. What you propose would be almost impossible to test though. Sure, you can test for distinction quite easily, but measuring the cost/benefit of it in evolutionary terms is a lot harder. There is a trade-off to make here in what perception the eyes and brain are optimised for, perhaps other forms of perception will suffer to the point of it not being worth it. Also, bad news regarding UV: our cones can perceive it, but our lens filters it out, suggesting it has too many disadvantages. The main reason is likely because UV light creates too much chromatic abberration in a single-lens system, making it hard for us to focus properly[2]. This is not a problem for the kind of vision required by a honey bee, but it would be for humans. [0] http://science.sciencemag.org/content/343/6169/411 http://science.sciencemag.org/content/343/6169/411 [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC208822/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC208822/ [2] https://en.wikipedia.org/wiki/Chromatic_aberration https://en.wikipedia.org/wiki/Chromatic_aberration
pipio21 9y ago
The article made me doubt, so I called my dogs. All my dogs have the eyes clearly in the front, so I spent some time trying to find dog races with eyes on the sides on google Images. I found none. It is not a good idea for your credibility that the first thing you say in an article is blatantly false.
bsanderson 9y ago
It would be interesting to design a UI colour scheme specifically with this in mind, with strategic use of red vs green for focusing attention in a way that parallels the eye's natural biological tuning, as a similar approach to accessibility UI design for colour-blindness. If anyone knows anything like that that's been tried I'd be really interested.
- vanderZwan 9y ago
  We already use colour schemes tuned to our perception. They naturally converge on them. Have you never noticed how colour blind people always complain that so many interfaces use red and green as two opposing colours? Or how those colours are overused in carthography? Because we do.
- GuB-42 9y ago
  I don't know if it is ironic or if there is something I didn't understand... That's because you just described traffic lights. Now, I don't think a lot of biological research have been done when deciding the colors of traffic lights, there is research about why they feel so obvious. The idea is: Red is the most noticeable color, good for signaling danger or requiring attention. Green is distinct from red, it is also the brightest color, so it is good as a complement for red. Yellow is simply the intermediate between red and green.
  - bsanderson 9y ago
    Agreed that we probably end up on that naturally for things like traffic lights or danger signs, but I was thinking more interns of a full UI with that approach as an integral, conscious design consideration... based on more in depth and sophisticated study of replicating colour schemes in a natural environment in a broader sense.

77 points by pablode 9y ago

So are trichromatic people colorblind to tetrachromats? BTW. Wikipedia says that trichromatism was normal for mammals in the past, and then they lost one or two cones, which would suggest a different development path. The article does not touch on this. Or did distinct cones were reduced, and then one of them split into two again? It's also interesting whether chemical structure of cones is similar. I guess I gotta do some research on my own.

dingo_bat 9y ago

https://imgur.com/a/jdVqE https://imgur.com/a/jdVqE Boy that's some next level webpage design!

pablode 9y ago
Url is optimized for mobile (and without the banner). This one is more suited for desktop use [1]. [1] https://aeon.co/ideas/the-red-and-green-specialists-why-human-colour-vision-is-so-odd https://aeon.co/ideas/the-red-and-green-specialists-why-huma...
- dingo_bat 9y ago
  Interestingly, this link works properly on both mobile and desktop. Wonder why the original link is even needed.
  - rhn_mk1 9y ago
    To avoid loading the images with the page. They appear later through a JS mechanism (to the disappointment of noscripters).

nadohs 9y ago

Incredibly stupid experiment. As someone who is red-green color weak, just as 10% of the male population is, I feel insulted by the implication of this article and the obvious glossing over the fact that not all humans see green/red very strongly. This is lazy science, seriously asking people to differentiate between images of apes that want to mate? It made no sense, you basically proved that some people are colorblind... ok. Did you plan and write this over a weekend? Why did you even bother?

vanderZwan 9y ago
As a fellow colour-blind person (protanomally): you're reading implications that are not in the article.
- nadohs 9y ago
  ...

rowyourboat 9y ago

> Instead of having good vision, dogs, horses, mice, antelope – in fact, most mammals generally – have long damp snouts that they use to sniff things with. It is we humans, and apes and monkeys, who are different. What a load of bull. Dogs and wolves eyes are facing forward, as do cats', owls', jumping spiders' main eyes, and generally those of most hunting predators. Eyes facing forward is good for depth perception and judging speeds and thus hunting, a bigger field of view is good for detecting threats from any and all directions and thus for prey animals. The location of the eyes depends mainly on where the animals sits on the predator<->prey scale. Apes tend to be apex predators, thus the predator eye location.

geon 9y ago
Dog have worse resolution, color perception and depth perception than humans. http://servicedogcentral.org/content/node/391 http://servicedogcentral.org/content/node/391
- rowyourboat 9y ago
  I was contesting the statement that forward-facing eyes somehow make us special. They don't. They are a trait we share with most predators.
  - geon 9y ago
    The eyes of dogs are less forward facing than on humans.
  - woodandsteel 9y ago
    But our primate ancestors who originally evolved forward-facing eyes were not predators. Makes much more sense to think it was to help in swinging from limb to limb in trees.
simoom22 9y ago
All primates having forward facing eyes, but lemurs and sloths are only apex predators if you're a berry.

vanderZwan 9y ago

As a colour-blind person, this article both makes sense to me, and at the same time it doesn't. I have often wondered why human colour vision is not evenly distributed across the spectrum of visible light. This seems like a decent enough model for why that might be the case. However, that makes it very peculiar that there are so many people with colour-blindness like me, especially if it would be such a strong evolutionary advantage. One would expect selection pressure to have removed those genes from the gene pool by now. My own pet hypothesis is that it has to do with humans being a social species. For us, individual specialisation has much bigger evolutionary benefit, since it is shared, and a lower evolutionary cost, because other members of the group can compensate for shortcomings. To give an overly simplified "economic" model of it: when we collaborate properly, the net performance of a group is not the average performance of all members, but the sum of the maximum performance of individuals. So back to colour-blindness. It is fairly well-established that dichromatic colour-blindness helps see through certain types of camouflage. In a hunter/gatherer society, having one member of the group who is good at spotting prey animals (or dangerous predators, for that matter) is a huge advantage for the group, and your friends can assist you with getting ripe berries.

lucozade 9y ago
There is an alternative hypothesis. That it's just an evolutionary accident. Possibly it's a side effect of some other factor that is significant. I mean, we get a lot of evolutionary traits because of bias through natural selection. But there's probably not much reason to lose a trait if there's no selection pressure to. It still may happen,of course. It's possible we'll all have brown eyes some time down the road. But it's not obviously because of natural selection.
- vanderZwan 9y ago
  Of course, there may be no strong selection pressure against it. But the odd bias for red-green distinction has been there from the earliest primates, suggesting there is a strong selection pressure in favour of specialising in red-green hue distinction. This then goes directly against having no ability to distinguish so many green and red hues. Well, unless the only genetic way to maintain this bias includes a risk of colour-blindness, but I kinda doubt that. Tangent: actually, eye colour is very strongly influenced by natural selection. Specifically, IIRC it's one of the prime examples of social and/or sexual selection pressure being stronger than other pressures, precisely because it has no other survival advantage/disadvantage associated with it otherwise. Since social success is essential for individual survival in our species, being discriminated against for ethnicity in general is a selection pressure (and before I am misunderstood: evolution is an amoral context-optimiser and Social Darwinism is one of the worst perversions of a scientific theory ever).

bawana 9y ago

The article would have been more interesting if they addressed the peculiar fact that half of all women and all of spiders are tetrachromats. It would be interesting to add the cones for additional frequencies into a genetically engineered monkey. I can imagine that having vision in the infrared and UV would make animals better predators (like Predator)

sethammons 9y ago
Not half of woman. More like 2%. https://www.snopes.com/politics/medical/tetrachromacy.asp https://www.snopes.com/politics/medical/tetrachromacy.asp
vanderZwan 9y ago
And then there is the mantis shrimp with 12 different photoreceptors[0] As for genetically engineering an extra cone, they did that with mice, mainly to address the chicken-and-egg question: if you get an extra cone, does the brain learn to see extra colours? It seems like it would[1]. What you propose would be almost impossible to test though. Sure, you can test for distinction quite easily, but measuring the cost/benefit of it in evolutionary terms is a lot harder. There is a trade-off to make here in what perception the eyes and brain are optimised for, perhaps other forms of perception will suffer to the point of it not being worth it. Also, bad news regarding UV: our cones can perceive it, but our lens filters it out, suggesting it has too many disadvantages. The main reason is likely because UV light creates too much chromatic abberration in a single-lens system, making it hard for us to focus properly[2]. This is not a problem for the kind of vision required by a honey bee, but it would be for humans. [0] http://science.sciencemag.org/content/343/6169/411 http://science.sciencemag.org/content/343/6169/411 [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC208822/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC208822/ [2] https://en.wikipedia.org/wiki/Chromatic_aberration https://en.wikipedia.org/wiki/Chromatic_aberration

pipio21 9y ago

The article made me doubt, so I called my dogs. All my dogs have the eyes clearly in the front, so I spent some time trying to find dog races with eyes on the sides on google Images. I found none. It is not a good idea for your credibility that the first thing you say in an article is blatantly false.

bsanderson 9y ago

It would be interesting to design a UI colour scheme specifically with this in mind, with strategic use of red vs green for focusing attention in a way that parallels the eye's natural biological tuning, as a similar approach to accessibility UI design for colour-blindness. If anyone knows anything like that that's been tried I'd be really interested.

vanderZwan 9y ago
We already use colour schemes tuned to our perception. They naturally converge on them. Have you never noticed how colour blind people always complain that so many interfaces use red and green as two opposing colours? Or how those colours are overused in carthography? Because we do.
GuB-42 9y ago
I don't know if it is ironic or if there is something I didn't understand... That's because you just described traffic lights. Now, I don't think a lot of biological research have been done when deciding the colors of traffic lights, there is research about why they feel so obvious. The idea is: Red is the most noticeable color, good for signaling danger or requiring attention. Green is distinct from red, it is also the brightest color, so it is good as a complement for red. Yellow is simply the intermediate between red and green.
- bsanderson 9y ago
  Agreed that we probably end up on that naturally for things like traffic lights or danger signs, but I was thinking more interns of a full UI with that approach as an integral, conscious design consideration... based on more in depth and sophisticated study of replicating colour schemes in a natural environment in a broader sense.