In The Third Chimpanzee, Jared Diamond describes this pattern in highland New Guinea, one of the last places in the world to make contact with outsiders. He wrote, “When I was living among Elopi tribespeople in west New Guinea and wanted to cross the territory of the neighboring Fayu tribe in order to reach a nearby mountain, the Elopis explained to me matter-of-factly that the Fayus would kill me if I tried. From a New Guinea perspective, it seemed so perfectly natural and self-explanatory. Of course the Fayus will kill any trespasser: you surely don’t think they’re so stupid that they’d admit strangers to their territory? Strangers would just hunt their game animals, molest their women, introduce diseases, and reconnoiter the terrain in order to stage a raid later.” Before outside contact, New Guinea highlanders spent their entire lives within a few miles of their villages, and as far as we know, none had ever seen the sea, which was just 100 miles away. It seems likely the whole world was like this in prehistory.