One of my favorite things to think about is that brief (archaelogically speaking) period of time when modern humans shared the European landscape with Neanderthals . . . maybe 25,000 to 30,000 years ago . . . you could be walking along the plain with your fellow hunters and see off in the distance a similar group of creatures, doing similar things, but so alien, so distant, so different . . . but maybe not so alien to be repulsive, if you know what I mean (Captain Kirk knows what I'm talking about).