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Today, most mammals have dichromatic vision, meaning that they have two color receptors. Which color depends on which species you're asking. For example, the real reason bulls charge at matadors is the way they flaunt their flags--cattle CAN see color, but red does not register.

Other mammals, like dogs, have a different kind of color blindess:

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Trichromacy, having three color receptors, is pretty common among the whole animal kingdom--for example, we have recently found the "red" gene in turtles--but when talking mammals, exclusive to only one order--the primates.

Regardless, reports have been popping up in recent years of humans possessing the gene that results in tetrachromacy, FOUR color receptors. As proof, just Google up Concetta Antico, an Australian artist who has been getting quite a popularity for letting her genetic condition inspire her paintings.

In Antico's case, tetrachromacy is a mutation that is not routine in the human genetic structure. But in this alternate scenario, tetrachromacy is a genetic normality among all primates and trichromacy among all non-primate mammals. Among humans, would this improve our night vision?

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  • $\begingroup$ It would if the 4th color we are sensitive at is infrared policemag.com/channel/technology/articles/2013/03/… $\endgroup$ Dec 21 '16 at 22:46
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    $\begingroup$ Color is perceived in photopic vision, that is, day vision. Scotopic (or night) vision uses a different set of photosensitive cells which do not discriminate colors. The human brain is wired for trichromacy. Physical tetrachromacy is not exceedingly rare among women; Concetta Antico is one of the verty few functional tetrachromats, that is, her brain is able to process four color channels. $\endgroup$
    – AlexP
    Dec 21 '16 at 23:40
  • $\begingroup$ Tetrachromacy is the norm for non-mammals not trichromacy, so you are actually making color vision worse for everything but mammals. $\endgroup$
    – John
    Dec 21 '16 at 23:51
  • $\begingroup$ Did I say non-mammals? $\endgroup$ Dec 22 '16 at 0:03
  • $\begingroup$ Contact her and ask her! Here is her contact info $\endgroup$ Dec 22 '16 at 2:42
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Night vision is primarily handled by rod cells, which have little colour perception - so it seems unlikely that tetrachromacy (which presumably affects cone cells) would improve it at all. In fact, you may find the opposite happens - if it requires an increase in the number of cone cells then it may be at the expense of rod cells; this certainly seems to be the case in nature where animals with better night vision than us (such as cats) have worse colour vision.

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Probably not. The Wikipedia article on night vision lists the main reason for humans' mediocre night vision as the lack of a tapetum lucidum. Many dichromat animals possess this and have excellent night vision, so tetrachromacy would be unlikely to help.

There would be some interesting other effects, too. According to various sources, tetrachromats experience an extremely wide range of color variations imperceptible to normal trichromats. If everyone was a tetrachromat, everyone would have this extra experience. I would predict that visual art would become even more important in society than it is in real life. Other mammals would no longer be color-blind by real-life human standards, but would still be by fictional human standards. And then there would be pentachromats arising from mutations, too... Apart from that, not that much would probably change.

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No, It would do the opposite To have color vision with more pigments we would have more cones in the eye, thus we would have fewer rods in eye, making our night vision worse. Rods are the cells that can handle low light cones don't work in low light. There is a reason mammals have better night vision than birds. Tetrachromacy is actually the norm for most terrestrial life, mammals lost most of their color vision (2/4 pigments) in return for much better night vision.

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  • $\begingroup$ There is no reason that the number of rods would necessarily decrease. There could just be fewer of each type of cone. Owls have excellent night vision, for example, by just having very few cones at all. $\endgroup$ Dec 30 '16 at 21:53
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    $\begingroup$ that would give them poorer color vision resolution, fewer cells equals poorer resolution. Owls also turn the eye into a weird conical shaped to fit in enough cells to the point that they cannot move their eyes. owls have extreme tunnel vision and few to no cones and have very poor color vision becasue of it. So again no you can't have it both ways, there just is not enough room in the eye. $\endgroup$
    – John
    Dec 31 '16 at 1:22

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