For Europe that would certainly be post-glacial rebound. Gulf of Bothnia cut off from the Baltic Sea, and England slowly sinking (many people would have strong

For Europe that would certainly be post-glacial rebound. Gulf of Bothnia cut off from the Baltic Sea, and England slowly sinking (many people would have strong opinions about it, I guess). Netherlands and Venice are a league on their own with sea flooding problems. Then pale skin and blonde/red hairs evolved when humans started to reclaim land after withdrawal of glacier in the same region of Europe, so 5k-10k years is sufficient for a new appearance feature in humans to evolve.