Cheyan (cheyinka) wrote in little_details,

Effect of total sunlight deprivation on skin color

My story is set in the 2030s on Mars.

A group of human scientists from Earth have discovered an underground, alien-made habitat with humans inside it, and I'm wondering what color the skin of the habitat-dwelling humans would be. They were all taken from what would today be Ohio, in the mid-1100s CE, and none of them have ever been exposed to sunlight (or any other kind of ultraviolet radiation) at any point in their lives.

I know that the skin generates melanin to protect itself against UV rays, and that darker-skinned humans don't have more melanocytes than fairer-skinned humans, but rather their melanocytes produce more melanin with the same amount of exposure - I just don't know how much melanin would be produced with *no* ultraviolet exposure. It doesn't make sense that there wouldn't be any at all, as I gather that there's a range of colors in newborn skin.

Also, I assume that their hair would be black or dark brown, even without exposure to sunlight, since typically sunlight lightens hair rather than darkening it. Am I on the wrong track here? [Edit: I know people can have light hair without sun exposure, but since people can have dark hair without sun exposure, melanin in hair doesn't need to be "activated" - so if the population initially had dark hair, they'd still have dark hair centuries later. Right?]

(I know the sunlight-deprived individuals will need a variety of supplements, and they're not being kept in the dark, just away from sunlight. This will have gone on for generations by the time they appear in the story I'm writing, but I'm pretty sure 800-900 years is too little time for their *genes* to be affected.)

Google searches: "melanin"; "skin color without sunlight", "sunlight deprivation", "newborn skin color"
Wikipedia: Human skin color, Melanogenesis, Melanin, Sun tanning
I have also read (which gives me the effects of not being in sunlight for a while, but not what would happen to someone who had never been in sunlight)

[Edit: The original post said "600-700 years". This is because I can't do math. Obviously 1100s to 2030s is 930 to 840 years.]
Tags: ~medicine (misc)

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