I had to double check some things but it seems like most mammals are assumed to have S-cones and L-cones. Meaning they are dichromats. Red-green color blindness. Also called Deutan.
But S-cones and M-cones are also dichromats. And that is also Red-green color blindness. Also called Protan.
The thing that suprised me was that they actually see red light, the L-cone, but can't distinguish this from green.
If they would have M-cones but no L-cones they would see red being dimmer or darker.
It is believed that before the first mammals they were all tetrachromats, seeing 4 colors, but mammals then lost 2 of them. And apparently that is because dichromats sees colors better in the dark than trichromats, or tetrachromats. That also tracks why they are Deutans and not Protans.
...I wonder if human Protan/Deutans perform better or worse in dim light? Both between each others and trichromats.
ETA: According to this article at least white tail deer have not our M or L cones, but a middle of the road version of it. Making them somewhere between a human protan and human deutan. But they also apparently are sensitive to blue light around 20 times more than we are, which is beneficial during twilight when the dim light is mostly blue.
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u/modest_genius Feb 04 '25 edited Feb 05 '25
It's cool, right?
I had to double check some things but it seems like most mammals are assumed to have S-cones and L-cones. Meaning they are dichromats. Red-green color blindness. Also called Deutan.
But S-cones and M-cones are also dichromats. And that is also Red-green color blindness. Also called Protan.
The thing that suprised me was that they actually see red light, the L-cone, but can't distinguish this from green.
If they would have M-cones but no L-cones they would see red being dimmer or darker.
It is believed that before the first mammals they were all tetrachromats, seeing 4 colors, but mammals then lost 2 of them. And apparently that is because dichromats sees colors better in the dark than trichromats, or tetrachromats. That also tracks why they are Deutans and not Protans.
...I wonder if human Protan/Deutans perform better or worse in dim light? Both between each others and trichromats.
ETA: According to this article at least white tail deer have not our M or L cones, but a middle of the road version of it. Making them somewhere between a human protan and human deutan. But they also apparently are sensitive to blue light around 20 times more than we are, which is beneficial during twilight when the dim light is mostly blue.