I was wondering, how would a civilization of humans who can see only in grayscale live their life? There is none of them that can see color. Everyone sees every thing in gray. Yet, color actually do exists. The environment they live in is Earth-like. Plants, animals, even the humans has color pigments and their sun is very much like ours.

How would being monochromatic affect their life and psychology? How would they see animals since both are monochromatic? Would most humans be vegetarian since they feel similarities with the animals (being monochromatic)? What events that happened in our world (world wars, development of airplane, nuclear science, etc.) that would be impossible to happen in their world due to them being monochromatic?

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    $\begingroup$ Art would be a little less... colourful. $\endgroup$ Oct 13 '16 at 10:10
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    $\begingroup$ I believe the book The Giver (en.wikipedia.org/wiki/The_Giver) was a lot like this. Maybe a good reference, if not just a good read. $\endgroup$
    – Pleiades
    Oct 13 '16 at 14:21
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    $\begingroup$ Your humans would have established a pretty solid tradition of meat eating before they realized that some animals saw the world the same way. A relatively small amount of mammals are monochromatic. en.wikipedia.org/wiki/Monochromacy $\endgroup$
    – SethWhite
    Oct 13 '16 at 15:53
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    $\begingroup$ @Harry Art may still be colourful; they just wouldn't know it. They may inadvertently use colours to represent the greyscale. It would be very interesting to see(for us). $\endgroup$
    – n00dles
    Oct 13 '16 at 17:00
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    $\begingroup$ Most common mammals are dichromats: they see two fundamental colors rather than the three that primates do. Also note that black & white illustrations were common in books and newspapers for centuries (and still are), black & white photography was the norm for a century or so, and TV was popular for decades before color TVs became available. So color is not necessary. $\endgroup$
    – jamesqf
    Oct 13 '16 at 17:58

Not any different

There are plenty of aspects of the physical world that we as humans cannot detect or distinguish between.

...and we seem to be getting along just fine without that, even though there are plenty of animal species that can perceive these things.

This is simply because the things that we can sense are all that we know. Our senses make up our view of the world, and this is so natural and common to us that we do not even contemplate about these limitations.

If our senses had been different, we would not have been different, because — again — our senses make up our world. And as long as everyone have the same kind of senses, and there is no differentiation, like for instance color blindness while others can still see color, then there is no reason this would make for a major difference in psychology.

Only when we gain or lose part of our senses does it tend to affect us in a major way.

Only when we know what it is like to actually have (or not have) some senses do we have anything to compare with. As long as everything stays the same, we do not know anything expect that which we have always had.

So in short: no, you cannot expect this to have any profound impact. There will be small differences, such as that we will not invent color TV, but in large there will not be much difference at all.

  • $\begingroup$ Some evolutionary advantage drove the development of our chromatic eyes, since they are more complex. Maybe it gives an advantage in spotting camouflaged preditors or prey? hard to say if that would make a difference. Maybe we'd never have survived at all, being killed off by man eating zebras hiding in long green grass. $\endgroup$
    – Innovine
    Oct 13 '16 at 10:53
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    $\begingroup$ @Innovine I see what you mean. It is just that OP asked if there would be any significant differences, not for us to generate ideas what the differences would be. :) $\endgroup$
    – MichaelK
    Oct 13 '16 at 11:08
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    $\begingroup$ There would be a difference in electronics as they would need to make either wires more tactile or have a different appearance (such as braided and non-braided) to be able to distinguish them for mass production $\endgroup$
    – IrateDwarf
    Oct 13 '16 at 13:34
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    $\begingroup$ @n00dles Look, as I said above: you cannot run evolution twice and expect to get the same result. Reboot evolution from our common ancestor and you cannot even be sure we get vertebrate animals again, or even animals, plants and bacteria. It will be different. But OP did not ask the question that way. OP asked us to assume that there are humans, just that they are color blind, and asked if that would have made humans significantly different in their life and psychology, or if our sciences would have been different. Answer: no, for reasons stated above. $\endgroup$
    – MichaelK
    Oct 13 '16 at 17:31
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    $\begingroup$ Your logic seems to be that because we are the way we are, changing us wouldn't change us. I don't see where you're going at all. Sure, we'd probably manage without color vision, but that's a far cry from saying everything would be exactly the same. Our ability to find edible food would be greatly diminished. Our ability to make color-coded charts would be non-existent. Color as an identifier of class would be greatly diminished. Noticing that a friend is bleeding would be harder. A lot would change without color vision. $\endgroup$
    – MichaelS
    Oct 15 '16 at 10:44

There's a little that might be different, particularly when it comes to food. Meat is not safe to eat if it isn't cooked enough, and it's not easy to tell whether it's cooked well enough without color (trust me, I'm colorblind, I know this). Similarly, early civilizations tended to avoid red berries and similar because such a high proportion of them were poisonous. As a result, it's possible that early colorblind civilizations would have stricter self-imposed dietary requirements - no berries at all, and meat might have to be burnt black. Alternatively, they might take a less risk-averse approach - all berries are fine, raw meat is fine. This would result in a pretty high death toll early on, but maybe they'd develop stronger stomachs after a few dozen generations.

I can't imagine that any particular events would be changed, but a number of technologies would be at least superficially different - as it stands, almost everything electronic uses a status light that changes color between a color that means "ready" and another that means "not ready" (and sometimes a third that means "something has gone horribly wrong"). That convention wouldn't work for these people. Since intensity is tricky to modulate, the best approach would be to simply have multiply different lights, clearly labelled.

Traffic lights would have to be set up differently; perhaps number of lights instead of color would need to be used.

In art (and aesthetics in general) pattern would be far more important than color. Being a little fanciful here, I could imagine that this might enhance early interest in geometry, and result in a more advanced state of mathematics by the modern era.

Medicine might be slightly inhibited early on - speaking from experience, it is hard to tell the difference between a rash and a bruise when you can't see the colors involved. I can't even tell the difference between a sunburn and a tan. There are a number of other medical conditions that before modern medical technology could only be identified through changes in the body's coloration; as far as your colorblind people would be able to tell, these conditions would be completely asymptomatic until the patient died!

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    $\begingroup$ There already exist traffic lights in our world which use symbols rather than colors. For example (Swedish Wikipedia article, sorry, but the pictures are illustrative enough) sv.wikipedia.org/wiki/Trafiksignal#Kollektivtrafiksignaler. $\endgroup$
    – user
    Oct 13 '16 at 11:15
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    $\begingroup$ @MichaelKjörling OK, that's wonderful. I wish the US would do the same... $\endgroup$ Oct 13 '16 at 11:17
  • $\begingroup$ Guess it's gonna be sashimi everywhere then. $\endgroup$ Oct 13 '16 at 12:53
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    $\begingroup$ There are traffic lights which use symbols rather than colours in the US and UK as well. We put the red light on top every time because of this. Well OK the US have those weird sideways ones but position, shape and colour can all be used to convey meaning. $\endgroup$
    – TafT
    Oct 13 '16 at 16:43
  • $\begingroup$ Re: "early civilizations tended to avoid red berries." So why are those berries red? It's because they evolved together with colour-sighted animals who were able to distinguish. So, better train yourself a dog. $\endgroup$ Oct 14 '16 at 11:19

Heat treatment of steel would be a bit harder to develop, because for quite a long time humans relied on colour to estimate if temperature is right. So transition to steel would be slower.

And that's about it. We eat pigs despite being about the same colour, so why any ideas about vegetarianism? Wars, airplanes etc are totally unrelated to colour.

Art would be bit simpler and cheaper in monochromatic perception, as you don't need dyes. That wouldn't be a great change for global economy though. Fashion wouldn't rely on color, obviously, so it would be more about shapes, and using different brightness of fabric to make specific shapes clearly visible or smoothly blend. Where we had extravagant colours to show how rich someone is, we would have texture, complicated weave and sewing techniques. These were known in real history, too, but played a secondary role before modern era of cheap dyes. In monochromatic world these would be the sole way to express one's wealth, so probably would develop earlier, and in more elaborate kinds.

With jewellery, cutting gems in a way that creates rainbows and faerie of colours would be pointless. Humans would still like shiny and rare items, and glittering would still have it's value, but obviously diamond cuts developed to bring colours would never develop. Natural crystal shapes might get more display, as a way to show how expensive item someone is wearing really is.

  • $\begingroup$ May be interesting to go into fashion a little more, you've teased us with "you don't need dyes" $\endgroup$
    – Liath
    Oct 13 '16 at 10:10
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    $\begingroup$ @Liath done :) Hope it helps. $\endgroup$
    – Mołot
    Oct 13 '16 at 10:14
  • $\begingroup$ Art simpler? Bob Ross begs to differ: m.imgur.com/gallery/yRsVB :) $\endgroup$
    – BrianH
    Oct 13 '16 at 12:45
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    $\begingroup$ @MatthieuM. Not really. Even now, amount of light in forge can affect perception of colour enough to fail to reach optimal temperature. Without colour, you would need to keep constant brightness in your forge, much more precise than it was possible most of the time. Soit wouldn't be reliable. Geez, even colour is far from perfect, brightness would be far worse. $\endgroup$
    – Mołot
    Oct 13 '16 at 14:14
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    $\begingroup$ @Mołot if it was altered it would need changed for all the creatures likely to eat said mushroom or berry. Things that feed on nectar see UV to go with the UV patters on flowers. We do not feed on nectar so there is little reason for us to see UV. Either you have humans that do not eat fruit or you have colourless fruit and all fruit eaters are also colour blind but how would anything then sense ripeness? Does it all got a different scent and we all get the ability to detect it from what would have been a visual distance? $\endgroup$
    – TafT
    Oct 14 '16 at 9:24

There would be less granulation in things we use for simple visual ques. For instance it's unlikely that stop lights would take the same form. Red Yellow Green. It's more likely that we would use shapes in conjunction with the light in those situations.

We use colour in a lot of things like that, so if we didn't change those to compensate and be more recognizable in other ways there may be a statistical drop in effectiveness when compared. (although who knows how big that would be given that this society would not be conditioned to the que they are missing)

It's likely we would put more intellectual value on shape. Art/Film/Fashion would certainly be different.

It's also harder to detect certain naturally occurring things. Changes in colour of phlem can indicate medical issues. The colour of blood in urine vs drinking too much coffee would be harder to detect and this has implications for catching things like bladder cancer.

EDIT: What i wrote below is probably not true as @Molot pointed out since computers were originally monochrome it's likely they would have just never gone through the iterations that wouldn't work well.

Computer interfaces would also likely be different. UI these days is generally decent at accounting for colour blindness but there are many cases of hard to use UI for the colour blind.

  • $\begingroup$ Well, I disagree with UI. Computer UI started as monochrome and ended as decently readable even without colour. Only thing missing would be the period when colour was all that important ;) $\endgroup$
    – Mołot
    Oct 13 '16 at 14:05

I think that what happened in the evolution of the real world was that the earliest mammal (still during the age of dinosaurs) was nocturnal (perhaps to avoid being eaten).

Being nocturnal, they lost the ability to see in color ... or they traded it for the ability to see in low-light conditions.

See Rods & Cones:

Rods are responsible for vision at low light levels (scotopic vision). They do not mediate color vision, and have a low spatial acuity.

Cones are active at higher light levels (photopic vision), are capable of color vision and are responsible for high spatial acuity.

After the end of the age of dinosaurs (about 65 million years ago) mammals evolved to become more dominant, no longer only nocturnal (but most mammal species retained monochromatic eyesight, since there was no especially compelling reason to evolve or select for color vision).

Plants were evolving too: by that time they had flowers, and maybe fruit. The theory is that fruit would become red to indicate when it was ripe (ready to be eaten), which (being red) was a signal that could be seen by birds (birds, not being mammals, never lost their original color vision).

At this point in history, primates (i.e. climbing monkeys), alone of all the mammals, re-aquired (evolved) ability to see in color again -- this would help them see ripe fruit (i.e. join the communication that was already happening between the fruiting plants and the birds). Humans, being primates, also have this color vision.

So, humans with monochromatic eyes: perhaps there wasn't colored fruit to see; maybe there was fruit but fruit didn't bother to change color when ripe (e.g. because birds didn't see in color).

Some possible results:

  • Maybe humans wouldn't be keen on sweet/sugar.
  • Maybe they'd be nocturnal, see better in the dark; and if it's true that mammals evolved warm-bloodedness and fur to be able move about at night even when it's cold, maybe nocturnal monochromatic humans would also still be furry.
  • Maybe humans couldn't see fine detail (if cones are responsible for "high spatial acuity" as well as a color) ... which might wipe out a lot of technology, i.e. everything from weaving cloth to vascular surgery, not to mention reading and soldering etc.
  • Maybe humans would have some other sense instead: better sense of hearing or touch, splendid sense of smell, or greater intelligence (intelligence is complex and can be measured along many axes, but maybe for example they'd be less careless, better at paying attention before they act).
  • Maybe they'd prefer low-light conditions: e.g. caves or deep forest.
  • $\begingroup$ This does not answer the question. Question is not about why would people be colorblind, but about civilization changes. It's about results, not reasons. $\endgroup$
    – Mołot
    Oct 13 '16 at 14:55
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    $\begingroup$ Two hypothetical results are in the last sentence. I'm assuming this is "science fiction" i.e. explaining a reason for such other-worldly results. $\endgroup$
    – ChrisW
    Oct 13 '16 at 14:58
  • $\begingroup$ @Molot Without understanding "why", answering "how different" is just arbitrary. Of course that is fine for stories, but "anything goes no matter the why" makes the question very broad. $\endgroup$
    – hyde
    Oct 14 '16 at 6:08

Their visual arts would be obviously different, and could be difficult for us to understand, as they would see different shades of pink, blue, and green as a continuous scale of grey, while we would see different colours.

It would also affect military fatigues. Neither it would have been a reason to make them bright blue/red as we used to see in the 19th century, nor to change them into the camouflage look of grey/brow/green shades that predominates nowadays. Not sure how this would affect the "art" of war, if at all. Similarly, their heraldics would have to be different, probably using much more black and white, and just one or two shades of grey.

And I wonder whether they would come up with spectrography of stars - or even of the flames of different chemical compounds - as they would not be looking for colours of things.

It is quite possible that people who evolved no colour sight would have evolved compensatory sensory abilities - finer hearing, tact, and perhaps more importantly, more accurate olphative perception (which could avoid the problems with raw meat and poisonous berries raised by Reese).


The frequency seen in grayscale may be very important. Green things would appear black to someone who only sees red light or blue light.

Infrared Monochromatic Vision Greyscale vision in the far(ish) infrared area of the spectrum could show hotter things as brighter. An example of this is we humans can actually kind of see the temperature of things once they get very hot: the element on a stove is not as hot as the filament of an incandescent lightbulb, and we can visually see that by brightness. We have a disadvantage in the our area of the spectrum: room temperature things do not emit enough light in our visible range to detect it; and an advantage of seeing colour: something blue hot is hotter than something white hot is hotter than something red hot. Those who see in monochromatic infra-red would be visually much more sensitive to the temperature of objects near room temperature.


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