This question is based on the articles saying that the Mongoloid body plan was all due to an individual mutation from 35,000 years ago.

In science fiction, humanoid aliens that aren't of the human species are rampant.

enter image description here The sensual, shamrock-green seductresses of the constellation Orion.

enter image description here The blue or purple-skinned Asari.

These two are minimally alien. The most obvious difference is skin color. In our ethnogeographic history, there has never been evidence of a mutation turning human skin green, blue or purple. But among humans on Earth, could such genetic mutations be possible?

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    $\begingroup$ Not genetic but silver ingestion causes blue skin. $\endgroup$ Commented Dec 21, 2016 at 18:18
  • $\begingroup$ It's a tricky business! I'll ignore the blue fugates, how bout gorging down hundreds of potatoes dip in iodine... actually I found out no need iodine!💀 $\endgroup$
    – user6760
    Commented Dec 22, 2016 at 4:43
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    $\begingroup$ Nit: one can’t be “from” a constellation. Her ancesstors were from a planet named Orion. $\endgroup$
    – JDługosz
    Commented Dec 27, 2016 at 5:15
  • $\begingroup$ I’m serious about getting accurate flesh tones, even if they’re green. I adjusted the photo to match Mac Landscape Green though in sRGB it’s lacking. So, I don’t think your example of Susan Oliver is Shamrock. $\endgroup$
    – JDługosz
    Commented Dec 27, 2016 at 5:27
  • $\begingroup$ @JDługosz Do you know any other shades of green that fit the alliteration? $\endgroup$ Commented Dec 27, 2016 at 5:33

4 Answers 4


If our eyes can do it, our skin can do it. Depicted: Frank Sinatra and Emma Stone.

Frank Sinatra and Emma Stone

Humans have only one pigment molecule: melanin. Brown, blue and green eyes are caused by different distributions of melanin molecules in the eye, and different proportion of light absorbed and light scattered.


Melanin absorbs light, so the more melanin there is, the less light will be (reflected back out of the eye). Brown-eyed people have more melanin, less light.

The opposite is true for people with "blue" eyes. Those with less melanocytes can't absorb as much light, so more light is reflected back out of the eye. This is called scattering — and when light is scattered, it reflects back at shorter wavelengths. On the color spectrum, shorter light wavelengths correspond with the color — you guessed it — blue.

This Rayleigh scattering is the same thing which makes the sky look blue. If distribution of melanin in the eye can make blue or green there, it can make it in the skin as well.

There is another way to make green. We normally have bilirubin in our blood. It is a breakdown product of hemoglobin. Jaundice is caused by a buildup of bilirubin, from liver dysfunction or blockage of the bile ducts. Bilirubin is a sickly yellow color but biliverdin, a precursor product, is a vivid green. You can see this green in an old bruise: blood trapped beneath the skin goes from a dark purple to a vivid green to a mustard yellow as the hemoglobin breaks down.

Hemoglobin / biliverdin / biulirubin colors

Higher levels of heme breakdown products in the blood are not in themselves bad for you. A mutant which accumulated biliverdin in the blood and only slowly broke it down to bilirubin would have skin (and sclera) the vivid green of this pigment.

I found a described case of exactly this. This man turned bright green (as opposed to the typical yellow) when he became ill with end stage cirrhosis. His urine was also bright green.

Biomedical Scientist p362 June 2011

Results of the investigation suggested that green jaundice in this patient was the result of reduced biliverdin reductase activity that converts biliverdin to bilirubin, perhaps due to a defect in the gene that codes for the enzyme. Analysis of DNA from the patient’s blood cells and subsequent sequencing of his bilirubin reductase gene provided confirmation that this was indeed the case.


Yes, but probably just blue/purple.

It's not very likely for humans, but other primates do develop blue skin, so it's feasible that humans could (given our common ancestor).

enter image description here $_{Source}$

This paper describes that the blue coloring of the Mandrill flank (and another monkey's blue scrotum) is not due to pigmentation, but rather arises from a nanostructure that makes the skin appear blue.

We used fibre-optic spectrophotometry, light microscope histology, transmission electron microscopy (TEM) and 2-D Fourier analysis of TEM images to investigate structurally coloured skin from four species of mammals: the mandrill, Mandrillus sphinx, and the vervet monkey, C. aethiops (Cercopithecidae; Primates); and the mouse opossum, Marmosa mexicana, and the wooly opossum, Caluromys derbianus (Didelphidae; Marsupialia). We found that structural colours of mammal skin are produced by coherent scattering from quasi-ordered arrays of dermal collagen fibres. These arrays are exactly convergent with colour-producing collagen that has evolved numerous independent times in the skin of birds (Prum and Torres, 2003a), in the tapetum fibrosum of the sheep eye (Bellairs et al., 1975) and in the iridescent corneal stroma of certain fishes (Lythgoe, 1974).

I think knowing the likely genetic source makes it a little less alluring than the blue alien/human/people are meant to be. If you met a blue person (hard to say they'd be human) you might not be able to stop thinking that they share that trait with monkey perineum, buttocks, and/or scrotum.

It might even make Kirk think twice. But probably not.

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    $\begingroup$ Orange or bloodred seem like likely colors as well, although I'm not sure. $\endgroup$ Commented Dec 21, 2016 at 19:02
  • $\begingroup$ @XandarTheZenon Entirely, but the OP asked about "green, blue or purple". $\endgroup$
    – Samuel
    Commented Dec 21, 2016 at 19:05
  • $\begingroup$ "I think knowing the likely genetic source makes it a little less alluring than the blue alien/human/people are meant to be." Meaning? $\endgroup$ Commented Dec 21, 2016 at 22:34
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    $\begingroup$ @JohnWDailey Well, in popular science fiction the green or blue women are usually portrayed as sexy. But, knowing they have that coloring because they're expressing monkey scrotum skin DNA is not very sexy. It's just a joke. $\endgroup$
    – Samuel
    Commented Dec 21, 2016 at 22:37
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    $\begingroup$ @Zxyrra Sure, green has an easy evolutionary advantage, but I couldn't find any cases of primates, or even mammals, stumbling upon that adaptation in nature (for hair or skin). So I deem it unlikely for the OP's question. $\endgroup$
    – Samuel
    Commented Dec 22, 2016 at 17:19

A conditional no we haven't, and a yes we could.

This will be a behavioral evolution trait in humans if it does come about. Same thing that occurred in Dino's...as much as we like to point towards survival of the fittest, in truth it's survival of the most capable of breeding and traits that attract mates tend to amplify quickly and get out of hand (a peacocks tail as a modern day example). No reason this trend couldn't happen in a population of humans.

The conditional above : We do have a blue skin mark as a semi common genetic trait...https://en.wikipedia.org/wiki/Mongolian_spot Mongolian spot (or mongolian blue spot) is a blue pigmentation on the skin (does that count as blue skin?). If this trait somehow became heavily favorable in attracting a mate, it could amplify in a few generations.

As a side note...blue/purple only. I really can't find much that pigments green.


No, humanity has never experienced that sort of pigmentation through any sort of natural mutation, and is unlikely to ever experience it either. After all, all the examples you've provided are of alien species from the far future.

It's quite possible that future genetic engineering, or nano-technology will allow people to customize their appearance to that degree.

  • $\begingroup$ The examples were just visual analogs. $\endgroup$ Commented Dec 21, 2016 at 18:25
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    $\begingroup$ To nitpick those examples are simple changes to make humans seem alien which only means it's not a normal thing now, not that it never could have been. Some monkeys have patches of colored skin, so it seems to be possible in primates, whether those colored patches do what we need skin to do I have no idea though. $\endgroup$
    – user25818
    Commented Dec 21, 2016 at 18:48
  • $\begingroup$ @notstoreboughtdirt - I'm not trying to nitpick, simply pointing out that there's no known precedent, and thus even the OP had to resort to imaginary future species. I could have cut my answer off at the first sentence, but that would have been a little short. $\endgroup$
    – AndreiROM
    Commented Dec 21, 2016 at 18:50
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    $\begingroup$ This isn't an answer. It is merely an assertion that it hasn't happened yet, but gives no further reasoning why it is impossible to occur naturally. $\endgroup$
    – SRM
    Commented Dec 22, 2016 at 2:34
  • $\begingroup$ Claims without reasons or evidence do nothing to help the OP. If everyone either said "yes" or "no" and ended it there, the OP would get absolutely nothing useful out of the question. It's most helpful to say "it won't happen in the future because _______" $\endgroup$
    – Zxyrra
    Commented Dec 22, 2016 at 3:09

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