Semi interesting story. Was driving my exwife around the city and noted how the color tint on one of the buildings as cool. It was a checkerboard pattern or something in different shades of blue/green. She couldn’t see it and said it was “glass colored”. She couldn’t really get how the glass was tinted a color.

Anyways printed out a handful of these and yep, she had partial color blindness. That’s how she found out.

[–] TheRealKuni@lemmy.world 32 points 4 weeks ago (10 children)

That’s fascinating! Colorblindness in XX women is very rare! Is her father colorblind?

As I understand it the genes for our cones comes from the X chromosome. So for women to be colorblind, their mother has to have one faulty X chromosome and their father has to be colorblind, so the woman can inherit two faulty X chromosomes.

Whereas men just need to inherit one faulty X chromosome from their mother and the Y chromosome from their father.

(Sorry, I’ve always been fascinated by color blindness. I had a friend in college who was quite bemused by how many questions I had for him when I learned he was colorblind.)

[–] modeler@lemmy.world 34 points 4 weeks ago (5 children)

This is true for only red and green loght detecting proteins (opsins) - the blue opsin gene is on chromosome 7.

The red and green detecting proteins have an interesting history in humans.

Fish, amphibians, lizards and birds have 4 different opsins: for red, green, yellow and blue colours. And the blue opsin sees up into the ultra-violet. Most animals can see waaaay more colours in the world than we (or any mammal) can. So what happened that makes mammal vision so poor?

It's thought that all mammals descend from one or a few species of nocturnal mammal that survived the catastrophe that wiped out the dinosaurs at the end of the Cretaceous. The colour detecting cells (the cones) need a lot of light compared to ones that see in black-and-white (the rods) and therefore nocturnal animals frequently lose cones in favour of the more sensitive rods for better night vision. The mammals that survived the Cretaceous extinction had also lost the green and yellow opsins while keeping red and blue - basically the two different ends of the light spectrum.

Consequently today most mammals still have only 2 opsins so your cat or dog is red-green colourblind.

Why do humans see green? Probably because our monkey forebears, who lived in trees and ate leaves, needed to distinguish red leaves and red fruit (visible to birds) from the green background.

But how did we bring back the green opsin? A whole section of the X chromosome (where the red opsin is coded) got duplicated in a dna copying mistake and then there were two genes for red opsins. As there are different alleles (versions), they could be selected for independently and so one red opsin drifted up the spectrum to be specific for green. So our green opsin is a completely different gene to the green opsin in fish, birds, etc. This kind of evolution happens a lot which is why, for example, there are many families of similar hormones like testosterone and estrogen. And steroids too.

[–] undefinedValue@programming.dev 2 points 4 weeks ago (2 children)

Why do humans see green? Probably because our monkey forebears, who lived in trees and ate leaves, needed to distinguish red leaves and red fruit (visible to birds) from the green background

We don’t evolve things cause we need it, evolution is driven by random mutations. Also we keep it if it’s better and helps us stay alive long enough to breed.

[–] EldritchFeminity@lemmy.blahaj.zone 7 points 4 weeks ago

I mean, you're really just arguing the semantics of phrasing.

Developing the ability to see green through random mutation was potentially an evolutionary advantage that allowed them to become better adapted to survival. Which is what they meant by "needed."

[–] TSG_Asmodeus@lemmy.world 6 points 4 weeks ago

We don’t evolve things cause we need it... Also we keep it if it’s better and helps us stay alive long enough to breed.

Why do humans see green? Probably because our monkey forebears, who lived in trees and ate leaves, needed to distinguish red leaves and red fruit (visible to birds) from the green background.

I feel like OP covered that.

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