It’s all about trust, cultural norms and territoriality. The average family size around the world is seven people, plus or minus two. The optimal team size is seven people, plus or minus two. Google’s new facilities in Switzerland and Ireland are filled not only with wide-open spaces, but with rooms with eight desks in them. Coincidence? Not likely. The anthropological research across cultures indicates that groups of seven people, plus or minus two, create the strongest trust bonds and best reinforce cultural norms.