Huh.
And here I thought it was from ancient ancestors centuries long practice of bathing in lye so’s they could blend in with the snow (ice age generally means snowy, you know) to make it easier to sneak up on reindeer while hunting same.
That fist sentence is kinda gumped. I don’t mean the ancient ones would bath in lye for centuries at a time, I mean a short bleaching bath prior to the hunt, done over and over for centuries.
"The consensus among scientists has always been that lower levels of vitamin D at higher latitudes — where the sun is less intense — caused the lightening effect when modern humans, who began darker-skinned, first migrated north. "
"Vitamin D plays an important role in bone growth and the body's natural protection against certain diseases, and the inability to absorb enough in areas of less-powerful sunlight would have decreased life expectancies in our African ancestors. The further north they trekked, the more vitamin D they needed and the lighter they got over the generations, due to natural selection. "