In the field of human biodiversity, there recently has been more attention on color variation, such as Rushton and Templer’s “Do pigmentation and the melanocortin system modulate aggression and sexuality in humans as they do in other animals?”
And as noted by Peter Frost and others, there seems to be same-race variation in pigmentation. Both among Europeans and North Asians, one finds that the upper classes tend to be fairer skinned, and the lower classes darker skinned. Think of the “fair princess” (beauty = fair skin) and epithets throughout literature, such as “white-armed Andomache” or the fact that fair-skinned women are often thought of as more virtuous.
Globally, women will go to great lengths to make themselves appear more fair, as skin-lightening products are some of the most-sold beauty products in the world. In short, surveying history, one could say fairness is adaptive; swarthiness, maladaptive, at least as they concern recent post-hunter-gatherer societies. Is fairness part of the domestication of Europeans and North Asians (as with foxes)?
Why, then, in the West, the radical changes of the past 40 years or so? Why is tanning among white women now considered hip? Why do some white women intentionally try to make themselves look darker?
In short, one could say much in the West is now dysgenic; whatever the media (and those who have real power) prescribe is probably contrary to reality.
Also note that the rise of the tanning phenomenon coincides with the sexual revolution. Does tanning of women denote sexual availability? Are tan women perceived as being sexually easier?
I have no hard data on this but from my experience (of frequently going out for a decade in major American and European cities) guys internally view fair women as marriage material, and overly tanned women as sluts. (If this is true, this could be a powerful weapon for women looking to snag a husband.)