Here’s an interesting question: why are Europeans so damn white? If you look at people from similar or even higher latitudes, Europeans are still damn white. I mean, when I grew up in Portland where there was no sun, I was incredibly pale. Once I moved to the UK, I suddenly had normal skin tone!
Anyway, here’s one explanation for our whiteness. The general idea goes as follows: human skin needs to be light enough to produce vitamin D but not too light to reduce folate (vitamin B9, basically). Most northern populations get their vitamin D from meat and fish. Europeans, however, subsisted on grains which do not contain this vitamin. In fact, Europe is special – even though it has very little sunlight, it can still grow grain. They support this by noting that art around the world suddenly starts depicting people as having light skin color.
In effect, Europeans are big babies! Pale skin, they suggest, swept along other features that are common in infants around the world that are lost to maturity, such as blonde hair and light-colored eyes. One could probably add a lactose tolerance that most of the world loses at a young age.
Of course, the arguments against this are obvious. First – we’re basing our history of skin color on cave paints? Really? Further, there’s the possibility that it’s due to genetic factors; maybe the founding population of Europe happened to have a gene that allowed this? After all, if you look at the aborigines in Australia, even the very southern people are much darker than you’d expect. Perhaps the opposite happened in Europe? It was recently reported in Science that the peoples who brought agriculture to Europe in what was basically a giant wave of colonization. Then again, you’d expect if that was the whole reason for the excessive lightness, the Sami people of northern Finland would be light-skinned due to even slight interbreeding with European populations. Instead, these hunter-gatherers got their vitamin D from meat-consumption. So maybe that’s not a big factor?