So at the end of the last ice age, or the beginning of the global warming period, When people could move North, they lost their tans.
Frikkin Scientific Geniuses they are.
Well, no, you're not quite getting it. Moving North doesn't make skin whiter (if that were true, there wouldn't be any black people in the US). Rather, mutations in genes, favored by natural selection, make skin whiter.
This study indicates that the mutations of interest occurred later than earlier hypotheses had suggested, but long after the first human beings migrated to Europe.