Summary at bottom.

I have a character from a homemade alien species. The species has silver/white hair and blue/violet eyes. I know these are traits of a melanin deficiency, but I imagined her having tan skin and some bright red skin markings. Could she have pale hair/eyes but colourful skin?I'm okay if the answer is no - if it's too complicated, I will just make the species all fair. I'm just curious.

For reference they evolved in a colossally sized, deep, dark rainforest so paleness probably makes sense (the colourful skin markings were for camouflage). Their environment also has a thin atmosphere so the air is thinner and temperatures are more drastic in certain places - not sure if that would effect their skin/hair/eyes.

  • $\begingroup$ @WeareMonica. changed it, hope this helps. $\endgroup$ – delaney Dec 7 '19 at 18:00
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    $\begingroup$ You first have to explain why your alien species would even have melanin in the first place, or why lacking it would be considered a deficiency? Perhaps your aliens have evolved to use carotinoids (what makes carrots orange) or anthocyanins (responsible for fall colors in decidous trees) instead. $\endgroup$ – jamesqf Dec 7 '19 at 18:22
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    $\begingroup$ @jamesqf Well... if I had enough knowledge on melanin/biology/whatever you're talking about, would I be on here asking questions about it or would I just be figuring it out myself? I'm an art student trying to write a story. Not everyone on here is equipped to answer those questions. That's why we're here. $\endgroup$ – delaney Dec 7 '19 at 18:26
  • $\begingroup$ I've edited the tags, so that you are asking for the plausibility of your idea - rather than any scientific critique of it. That's what reality-check is best for above the science-based one. I hope this helps you develop your ideas. If you don't like it, then you should feel free to revert the edit. $\endgroup$ – Tantalus' touch. Dec 7 '19 at 18:29
  • $\begingroup$ @delaney: OK, to make things really simple, your alien is something that evolved on another planet. That means that there is no reason why it would use the same pigment chemical as Earth mammals. It could use any pigment, within the limits of basic chemistry. Though if you want to have red patterns, or other bright colors, your alien to be at least trichromatic. Earth mammals are mostly dichromats, except for primates which regained trichromaticity revatively recently (in evolutionary terms), which probably explains why they mostly just use boring brown melanin for coloration. $\endgroup$ – jamesqf Dec 8 '19 at 2:11

This question makes a number of different assumptions, most of which are wrong.

1. The biggest, as covered by Slarty's answer, is that an alien species would even use the same pigments that Earth species use.

It's a common misconception that evolution is a gradual progression to the most efficient solution to a problem. It's not. For a trait to exist in many or all Earth species doesn't mean that it was the best or only trait to provide the needed functionality. It just happened to be the one that some common ancestor ended up with, and wasn't ever enough of a hindrance to be selected away.

We don't even know if alien life will use DNA the same way Earth life does, much less melanin and other pigmentation.

2. Melanin is required for pigmentation.

You're probably aware that most tree leaves are green. You likely know why, too. (If you don't, I'll give you a hint. It's not melanin.) Fish have three different pigments, Erythrin, Melanin, and Xanthrin. Birds use carotenoids, melanins, and porphyrins. Just because a species doesn't have any melanin, doesn't mean it has no pigmentation at all.

3. The presence of pigmentation is binary, either you have it or you don't.

You're probably familiar with the term albino, for a person or animal with a total lack of pigmentation. But there's a much less commonly known trait called leucism, where an animal will only partially lack their natural pigmentation. Sometimes this just means that their eyes are blue instead of pink, but it can also lead to some stunning piebald effects

4. Blue or red eyes necessarily means a lack of pigmentation elsewhere

And now I bring you the Blue-eyed black lemur, which naturally has shockingly blue eyes despite a black or tan fur coloration. Similarly, the red-eyed tree frog has (you guessed it!) brilliant red eyes.

The natural world is full of variations and exceptions. Never assume that just because two traits are commonly associated, that they are always related. You might as well say that all winged animals are birds, or that all vertebrates have spines. There's always an exception.

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  • $\begingroup$ WRT #3, the most obvious example is the wide range of human skin & hair colors, due to differences in melanin concentration. #4: Blue eyes are also common in some dog breeds, even though they have much the same coat colors as their brown-eyed kin: mysmelly.com/content/dogs/breeds-of-dogs-with-blue-eyes.htm $\endgroup$ – jamesqf Dec 8 '19 at 2:28

Yes it’s all possible. But melanin probably wouldn’t be used by the aliens or at least probably wouldn’t be used for the same purpose. With a completely alien biogenesis and billions of years of randomly triggered evolution most of the biochemistry will likely be completely different.

If the rain forest they evolved in is dark it would make sense that they were dark as well, but there are many reasons why this might not be the case. Sexual selection can produce some amazing structures. For instance the peacock’s tail is not very camouflaged but is still successful at surviving because they are favoured by female peacocks.

Temperature might well affect the alien’s evolution but is more likely to affect skin insulation and thickness than colouration. And colour adaptions to reflect or absorb heat have to compete with other possibly more important considerations. Polar bears are white for camouflage not black to absorb heat.

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  • $\begingroup$ Wait, but don't all creatures have melanin? How would my species not use it? Or use it differently? I can ask Google if you are busy but you could probably give me a better answer - thanks! $\endgroup$ – delaney Dec 7 '19 at 19:59
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    $\begingroup$ Earth creatures have melanin. Why would this mean that aliens who evolved in a totally different environment would use melanin? $\endgroup$ – Arcanist Lupus Dec 7 '19 at 20:40
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    $\begingroup$ Perhaps a little background would help. Every cell of every living organism is a vast molecular workshop where thousands of complex chemical reactions take place to help build and maintain the cell. You can see a part of the process here: biochemical-pathways.com/#/map/1 This process was not designed it evolved over billions of years of trial and error with random adjustments to the process. In an alien world evolution would unfold differently and the scope of chemical possibility is almost endless. Potential chemicals outnumber those in the diagram by many orders of magnitude. $\endgroup$ – Slarty Dec 7 '19 at 20:48
  • $\begingroup$ So regardless of the need (or lack) of melanin on Earth, it is unlikely to be needed on your alien world as the aliens would work differently because there are so very many different ways of achieving things chemicaly. $\endgroup$ – Slarty Dec 7 '19 at 20:51
  • $\begingroup$ @delaney: Even if other creatures have melanin, many of them also have other pigments. Bitds for instance use carotenoids & porphyrines: academy.allaboutbirds.org/how-birds-make-colorful-feathers They also use structural coloration, as in peafowl. On top of that, most birds are tetrachromats, which means they can see a whole range of colors that humans can't. $\endgroup$ – jamesqf Dec 8 '19 at 2:20

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