Pangaea

At least four times in Earth's history, the continents have come sliding together to form a single mass-a super-continent. Geologists have dubbed the most recent such formation Pangaea. Of course, Pangaea broke up a long time ago, and because it did, different portions of mankind developed in drastically different climes and circumstances. But what if we were living on one of the super-continents? What if all of humanity was confined to a single landmass . . . and had been so confined for a...