“Humans learn empathy and understanding by watching how their actions affect other people. Empathy can’t flourish without immediate feedback, and it’s a very slow-developing skill. One analysis of seventy-two studies found that empathy has declined among college students between 1979 and 2009. They’re less likely to take the perspective of other people, and show less concern for others. The problem is bad among boys, but it’s worse among girls. According to one study, one in three teenage girls say that people their age are mostly unkind to one another on social network sites. That’s true for one in eleven boys aged twelve to thirteen, and one in six boys aged fourteen to seventeen.”