In my story, there is a species of catarrhinian primate named demons (their scientific name is Homo demonus) (so there are still humans, just not Homo sapiens).

They look like a mixture of Afro-Asiatic demons (both Egyptian paganism and Egyptian neopaganism, Judaism, Christianity, Islam, and Bahaism), Indo-European demons (Hinduism, Buddhism, Sikhism, Jainism, both Greek paganism and Greek neopaganism, etc.), and Japanese demons (Shintoism):

  1. They are fossorial (like Afro-Asiatic demons);
  2. They can be of any morality, but because of their powers, they are physically more dangerous than anatomically modern humans, and they tend to have a blue and orange morality (some things like stealing, both sex and romance between juveniles and non-juveniles, and doing recreative drugs at any age, for example, are considered totally normal for them) (like both Indo-European and Japanese demons);
  3. They vary greatly in size (like Japanese demons);
  4. They are vespertine (mostly active during the dusk and evening) (like Indo-European demons);
  5. They have horns (like both Afro-Asiatic and Japanese demons);
  6. They have a venomous bite (like both Afro-Asiatic and Indo-European demons);
  7. They have possession powers (like all of the three);
  8. They are eusocial (unlike any of the three) (their eusociality looks like a mixture of naked mole-rats and termites).

Also, demons are MUCH more likely to be colour blind than anatomically modern humans:

  • 24 % of genetically male demons and 1.22 % of genetically female demons are green-red colour blind (in Caucasoid anatomically modern human populations, 8 % of genetic males and 0.5 % of genetic females are green-red colour blind) (green-red colour blindness includes protanopia, protanomaly, deuteranopia, deuteranomaly, and blue cone monochromacy) (except that in anatomically modern humans, deuteranomaly is the most common of the five, the second most common is protanomaly, the third the most common is protanopia, the second rarest is deuteranopia, and blue cone monochromacy, the rarest) (in demons, from the most common to the rarest: protanomaly, deuteranomaly, deuteranopia, protanopia, and blue cone monochromacy, they are respectively found in 12 %, 6 %, 4 %, 3 %, and 1 % of genetic males);
  • 10 % of demons of any genetic sex have blue-yellow/blue-green colour blindness (7 % have tritanomaly, and 3 % have tritanopia) (in comparison, only 0.01 % of anatomically modern humans have tritanomaly, and 0.015 % of anatomically modern humans have tritanopia);
  • 1 % of demons of any genetic sex have achromatopsia (only one anatomically modern human out of 33,000 have achromatopsia in non-inbred populations).

So, I wonder why would demons be MUCH more likely to have dyschromatopsia than anatomically modern humans.

  • 1
    $\begingroup$ You may want to check your arithmetic. For example, if females are so much less likely than males to have less-than-normal red-green color discrimination, it follows that this is a condition triggered by homozygosis on a locus on the X chromosome. But $\sqrt{0.015}$ is $0.122$, half of your $0.24$. $\endgroup$
    – AlexP
    Jul 17, 2022 at 14:44
  • $\begingroup$ Can you be catarrhinian and be in the homo genus? I thought the catarrhinians were monkeys. $\endgroup$
    – Willk
    Jul 17, 2022 at 15:54
  • $\begingroup$ Yes. Catarrhines only means Old World simians (so technically, apes like humans are from this clade too). $\endgroup$ Jul 17, 2022 at 15:57
  • 1
    $\begingroup$ @Willk: Primates are of two kinds -- strepsirrhines (wet-nosed) lemurs, and haplorrhines (dry-nosed) monkeys and apes. Haplorrhines are of two kinds -- platyrrhines (flat-nosed) New World monkeys, and catarrhines (downward-nosed) Old World monkeys and apes. Catarrhines are of two kinds -- the superfamilies Cercopithecoidea (Old World monkeys) and Hominoidea (apes) . $\endgroup$
    – AlexP
    Jul 17, 2022 at 19:49

1 Answer 1


Achromatopsia helps them see better in the dark. Perhaps they even see better than normal humans with it. This reflects their active times.

The others help see through camouflage because it is adapted to normal color vision. This reflects more hunting or more warfare.

  • 1
    $\begingroup$ This was where I was going. There is no DISadvantage to colorblindness if you always operate in the dark. I would say it would be more likely the whole species would be colorblind; otherwise, they may have adopted being nocturnal more recently and are slowly losing the ability to see color. $\endgroup$
    – DWKraus
    Jul 18, 2022 at 13:26

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