“Social animals are smart animals,” the social psychologist Jonathan Haidt explained in his 2006 book,  The Happiness Hypothesis . Once humans developed technologies like writing and printing, Haidt wrote, they could imagine communities beyond their immediate surroundings and thus invoke such things as a nation and even humanity. People are motivated to maintain constant, lightly mediated communication with each other, Haidt observes: “Success is largely a matter of playing the social game well.