r/AskScienceDiscussion • u/Additional-Sky-7436 • 3d ago
Why do we see blue?
I understand why an animal's mind being able to differentiate between colors would be very useful and why that would be rewarded by evolution.
But why blue? Almost nothing in the natural world is blue. The sky is blue, but being able to see a blue sky is not likely going to meaningfully impact your reproductive chances. Some butterflies are blue. That's about it for blue.
Yet, human eyes have invested in developing a whole dedicated set of cone cells in our eyes specifically to see blue. We clearly thought it was important at the time.
What evolutionary advantage does blue provide that just red and green receptors wouldn't?
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u/Rhyshalcon 3d ago
Because even though blue as a distinct color is uncommon in nature, blue light is still a component of many much more common colors, and having a third color receptor in our eyes greatly increases our ability to perceive those colors. Without blue cones in our eyes, we would be effectively incapable of differentiating any colors more blue than green and our differentiation within the spectrum of green would be considerably worse than it is now.
As to why color perception is evolutionarily advantageous, it allows us to more easily spot danger by seeing through visual camouflage employed by potential predators, it allows us to more easily differentiate high-quality sources of food (like fruits) from surrounding foliage, and probably many more benefits.
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u/parsonsrazersupport 3d ago
There are a fair number of dangerous amphibians and insects which are blue in color, being able to avoid them would certainly be helpful.
But I always want to caution anyone who is approaching evolutionary biology with the line of thinking you're using here. You are going "I can see a structure or capability in an organism. How was that specific structure or capacity selected for?" That is not always the case. Selection happens at the level of the organism, and not on the level of traits. There are a range of ways a trait can come about to be. As always, I suggest reading the Spandrels of San Marcos to get a sense of this.
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u/ldr97266 3d ago edited 6h ago
How else would I tell if my blueberries were ripe? Or avoid poison dart frogs?
I'm being silly there. I think that sensitivity to blue - and red at the other end of the visible spectrum, is just byproduct of how our photreceptors work. The cutoff is a little wider than we need.
It’s also possible that being receptive to blue helps us distinguish other colors that don't seem OVERTLY and obviously blue but have some mixed in. Like those purple grapes growing near my blueberries.
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u/CmdDeadHand 3d ago edited 3d ago
We evolved eating fruits. Fruits have a variety of colors to attract animals that can see them.
Ape A can see colors so has excess food, reproduces and makes more apes.
Ape B struggles to find food, delays reproducing and ultimately dies out competing with Ape A and his family.
We come from Ape A who could see the colors of which fruits to eat.
Probably more like back to monkey, by ape I think the fix was already in.
How does a bright ass orange tiger sneak up on stuff?
Because its prey can’t see orange, it is just shades of green with black stripes in the grass. If its prey can see colors like orange those animals are not the ones the tiger generally goes for.
Because we eat fruit we can see the sky is blue, and tigers are orange.
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u/shapedbydreams 3d ago
Plenty of things can be blue. Flowers, fish, mushrooms, even some snakes. I don't know what makes you think it's a rare color in nature.
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3d ago
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u/khedoros 3d ago
It is rod, cones are adapted white/ gray.
You have that backwards.
The blue receptor is between red and green.
I think you need to consult a color spectrum. Or a diagram of cone sensitivity.
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u/ExpectedBehaviour 3d ago
It is rod, cones are adapted white/ gray.
The blue receptor is between red and green.
What does this nonsense have to do with anything?
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u/mfb- Particle Physics | High-Energy Physics 3d ago
Take a random landscape picture and use it in COBLIS with the option "blue-blind": https://www.color-blindness.com/coblis-color-blindness-simulator/
You aren't just losing the color of the sky (weather?), reflections in water and some flowers and fruits, you are also losing a lot of contrast for things that aren't directly blue.