As for the other suggestion, that would involve the mammoth task of crossing the ices of Greenland during the post-ice age. It could of course be possible but common sense tells me that human movements (and evidence with skeletons too) were of a northwards type in the post-glacial, as hunters chased the last groups of big mammals (like deer and like mammoth much earlier in time) that moved north escaping climate change in southern europe. Since the Middle Paleolithic, Northern Europe had been a huge ice shelf until that time and that now it began to melt. Those southern hunters that refused to adapt to the new era must have been the first inhabitants to move into northern europe following their beasts once the ice age came to an end. Cave painting even came to an abrupt end at that time and the Sahara became a desert. Its painters must have themselves moved northwards too and influenced much of the Mediterranean and the Levant, whose art is entirely different from the cave painters of S.France/N.Spain.