I still laugh from time to time about a seminar I attended at Cambridge where anthropologists and moral philosophers were talking about morality in cross-cultural perspective and the subject of private property came up. After various know-it-alls suggested there was no deep basis for private property ("cultural construction"), an ethologist piped up, "Have you ever tried to take a banana from a gorilla?" and there was just dead silence for about a minute and then everyone pretended nothing had happened and just continued as they had been.