A monochromatic consociety

[Otto Kretschmer]

I wonder - how would the world look like if humans could only see in black and white? Would the development of civilization be hindered in any way?

I guess at least initially there might be issues with distinguishing ripe fruits from unripe ones although humans might develop for example a better sense of smell to compensate for this.

Later down the road there might be issues eith distinguishing bronze from iron. Gold would also not hold the same sway for monochromatic humans and might be mistaken for silver.

[linguistcat]

I can't give a decisive answer to this, but I think there are a few facts that are relevant here and might help figure this out:

1. While humans are trichromats (generally, with some people being color blind and a few individuals being tetrachomats) in full light, we only have one type of rod cell, the ones responsible for low light vision.
2. From a quick search, these rods have a sensitivity peak between 500 and 550 nm or between "green" and "blue" cones, and closer to green. They have little or no sensitivity to the red end of the usual visual spectrum. So, a bright blue-green object or a white object should be similarly visible in low light and things that are red would be basically black.

So from this, we could assume that having only one type of cone for normal daytime vision would be basically black and white vision but it would look different depending what the sensitivity peak and overall sensitivity curve for the single cone would be. Wavelengths outside the curve, no matter how bright, would look black; Colors closer to the peak would look brighter than ones far away. I don't know if a single color at the peak of sensitivity at a given intensity would look the same as "white" light at the same intensity ("white" = light over the visible spectrum of these alt-humans), or if the "white" light would be slightly brighter.

If anyone has any other thoughts or more knowledge about either the biology or physics, I'd love to hear more or know where I was off.

Best of luck Otto.

[keenir]

I wonder - how would the world look like if humans could only see in black and white? Would the development of civilization be hindered in any way?

I can't see how it would be, sorry. A good reference would be the book Island of the Colorblind though only the first part of the book is about the island and its achromatic population (and an achromatic Swede).

I guess at least initially there might be issues with distinguishing ripe fruits from unripe ones although humans might develop for example a better sense of smell to compensate for this.

Not really; yes, primates leaned into the development of color vision to better pick out ripe fruits...but achromatic humans don't have any problems in distinguishing ripe from unripe.

(that said, if you want your fictional humans to have a better sense of smell, thats up to you)

[WeepingElf]

Not really; yes, primates leaned into the development of color vision to better pick out ripe fruits...

Yep.

[alice]

I wonder - how would the world look like if humans could only see in black and white? Would the development of civilization be hindered in any way?

I can't see how it would be, sorry.

I see what you did there

Interesting question, though. I suspect humans would have become more sensitive to other stimuluses in compensation, in the same way as blind people commonly have a heightened sense of touch. And it's not that difficult to tell most metals apart by touch and feel; gold and lead are much denser than iron, for example, and mercury is a bit runny.

Additionally consisder looking at things on a black-and-white TV, or whatever the equivalent the youth use today is.

[keenir]

I wonder - how would the world look like if humans could only see in black and white? Would the development of civilization be hindered in any way?

I can't see how it would be, sorry.

I see what you did there

that was unintentional on my part; though I like the humor you pointed out; thank you.

Additionally consisder looking at things on a black-and-white TV, or whatever the equivalent the youth use today is.

Achromats can't see color, but they do see more details in shades/tones and textures...though they also say that bright light washes a lot of that out.

[Qwynegold]

Color would obviously have no importance in art. But I think striking patterns could be important. And like arabesques, geometric shapes and abstracts.

[zompist]

So from this, we could assume that having only one type of cone for normal daytime vision would be basically black and white vision but it would look different depending what the sensitivity peak and overall sensitivity curve for the single cone would be. Wavelengths outside the curve, no matter how bright, would look black; Colors closer to the peak would look brighter than ones far away.

I'm not sure you'd need both rods and cones. But since we have data on our cone system, let's use that.

We have three types of cones, S M L— for short, middle and long wavelengths. The spectral response curves look like this:


People often mislabel this graph with colors, e.g. painting the L curve red. This is wrong: the peak of the L curve is about 575 nm, which is a bright yellow. Only the frequencies above about 620 nm are "red." What we actually see are combinations of these curves. If you plot L - M you get a beautiful sine wave that allows the brain to infer frequency: where it's low that's "green", where it's high that's "red". But that's not relevant for achromats.

The question is, which cone is best for general vision? S is crappy: it doesn't respond to all visible light. M is probably best as it's pretty much centered on the visible spectrum.

What does this mean for perception? One theory of our daytime achromatic perception— that is, our perception of brightness— is that it's L + M. That creates a curve right in between those two, peaking at about 515 nm. That is in fact why yellow looks close to white: it is stimulating both types of cone strongly.

But as you can see, L + M is not far from either curve. If our perception was based on M only, we might lose a few dark reds and maybe be slightly more sensitive to indigo.

I don't know if a single color at the peak of sensitivity at a given intensity would look the same as "white" light at the same intensity ("white" = light over the visible spectrum of these alt-humans), or if the "white" light would be slightly brighter.

It would look precisely the same. When we see a color, we are not seeing wavelengths directly. For that bit of visual space, the eye is basically merging all the frequencies and reporting the average. That means that there are an infinite number of ways to see, e.g., yellow:

* a single-frequency source at 575 nm
* a light of 650 nm (red) and 540 nm (green) - this is what your computer monitor does
* the broad spectrum of colors emitted by the sun, minus some high-energy photons scattered by the air; this is why the sun is yellow
* any number of other combinations

The eye/brain does not do frequency analysis, so it has no way of distinguishing these alternatives.

(The brain does do frequency analysis on sound, which is why you can't arrange all sounds into a continuum.)

[linguistcat]

So from this, we could assume that having only one type of cone for normal daytime vision would be basically black and white vision but it would look different depending what the sensitivity peak and overall sensitivity curve for the single cone would be. Wavelengths outside the curve, no matter how bright, would look black; Colors closer to the peak would look brighter than ones far away.

I'm not sure you'd need both rods and cones. But since we have data on our cone system, let's use that.

Rods essentially become over exposed in bright light. So if these humans were supposed to have monochrome vision in daylight AND the level of low light vision we have now, they would need at least one of each type. I'm sure there are species that only have one or the other, so I'm not saying it couldn't be done. There are even species that have color low-light vision due to having multiple rods with different sensitivity peaks. Maybe this version of humans are even more diurnal than humans irl are, since I can't imagine anything similar to humans only having our relatively poor low light vision. You'd be getting into too many changes to lifestyle at that point.