Everyone knows that natural selection depends on passing on the genes necessary for survival and possibly an advantage in obtaining food. When certain genes became more valuable both for fight, flight, and food, it was a no-brainer for the species to evolve with light skins in the northern latitudes.
Therefore the lighter skin genes became more valuable in snow covered areas. Like the snow rabbit, light-skinned humans could hide easier, blending into the terrain while avoiding dinosaurs and marauding dark skinned people.
And like the polar bear at a seal’s air hole, they could blend into their surroundings for an ambush.
OF course, this meant going naked in the snow-covered terrain which led to the gene that today makes otherwise rational people to go swimming in icy water during the winter.
All of the above is true and can be proven with some Biblical and literary references too long to continue to pull your leg, eh?
The most critical factor regarding light skin in the North and Vitamin D synthesis and absorption is the development of rickets with the lack of adequate Vitamin D. Without enough D, the pelvis does not develop well, and childbirth becomes difficult if not impossible. Thus gentlemen instinctively prefer blonds and well developed hips, because such women are much better able to give birth to live children. And thus the gene spreads rapidly. Also, avoiding dinosaurs was never a factor for humans.