On Sat, 13 Dec 2014 03:53:26 -0500, Patrik Austin <[log in to unmask]> wrote:

>I've had no attempts of my own but in case you're interested in a biological point of view, it's known as Gloger's rule that warm-blooded animals living in intense sunlight have darker skin, so this would probably be true on an alien planet as well. There are known exceptions to the rule

The plain old adaptive theory seems to have won the day in at least the popular imagining (I don't really know the state of play among biologists) but one shouldn't forget sexual selection as an influence.  Among human phenotypic characters, skin colouration is far and away one of those at once most salient and least intrinsically influencing one's quality of life.  These are exactly the settings in which sexual selection thrives.  

I've lost my good links on this, but Peter Frost <> has written on it, and <> also discusses it.