
The red and green specialists: why human colour vision is so odd - pablode
https://aeon.co/amp/ideas/the-red-and-green-specialists-why-human-colour-vision-is-so-odd
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rowyourboat
> 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.

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geon
Dog have worse resolution, color perception and depth perception than humans.
[http://servicedogcentral.org/content/node/391](http://servicedogcentral.org/content/node/391)

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rowyourboat
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.

~~~
woodandsteel
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.

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vanderZwan
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.

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lucozade
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
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).

~~~
c256
> Tangent: eye color is very strongly influenced by natural selection...

Maybe, but then what’s your explanation for the prevalence of brown eyes due
to natural selection?

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vanderZwan
Do you realise that you are implying that sexual selection is in favour of
light eyes in general? This was not what I stated.

I merely talked about differentiating in- and out-groups, which is localised,
meaning the _homogeneity_ of an eye colour within an ethnicity can be
explained through sexual selection.

Regarding the prevalence of brown eyes, light eyes and hair are a recent and
recessive mutation. That is all that is required to explain why it is
localised and less common: it is limited to people who descended from the
point of origin of the mutation. In this case that would be Northern Europe.

[http://learn.genetics.utah.edu/content/basics/patterns/](http://learn.genetics.utah.edu/content/basics/patterns/)

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pipio21
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.

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luk32
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.

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bawana
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)

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sethammons
Not half of woman. More like 2%.

[https://www.snopes.com/politics/medical/tetrachromacy.asp](https://www.snopes.com/politics/medical/tetrachromacy.asp)

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bsanderson
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.

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GuB-42
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
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.

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dingo_bat
[https://imgur.com/a/jdVqE](https://imgur.com/a/jdVqE)

Boy that's some next level webpage design!

~~~
pablode
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-
huma...](https://aeon.co/ideas/the-red-and-green-specialists-why-human-colour-
vision-is-so-odd)

~~~
dingo_bat
Interestingly, this link works properly on both mobile and desktop. Wonder why
the original link is even needed.

~~~
rhn_mk1
To avoid loading the images with the page. They appear later through a JS
mechanism (to the disappointment of noscripters).

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nadohs
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?

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

~~~
nadohs
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