I enjoyed a recent episode of the "This American Life" podcast, about who is in the tribe and who isn't Here's a bit of the transcript, where the author of The World Until Yesterday describes how meeting new people is a new phenomenon created by modern societies. Jared Diamond: "The idea that you could just wander around and meet someone is utterly impossible in New Guinea. If you ran across a strange person on your land, that could only mean that they were there for some bad reason. They were there to scout out your land for a raid, or to steal a woman, or to steal a pig.
And so if you ran into a strange person in the forest and you couldn't run away from him, you came around a corner and there he was, then the two of you would sit down. And you'd have a long conversation in which each of you names all your relatives, trying to find some relative in common which gives you a reason not to kill each other. And if after two hours you haven't found any relative in common, then one of you starts running or you try to kill the other person."
So next time you meet someone, realize it's in your genes to find common ground with them. Sit down and find out what you have in common before you go any further. If that fails, I suggest that you take off running before they try to kill you!