New research has found that adults who are over age 50 are generally happier than their younger counterparts. Is it because the stress of getting stuck in traffic causes less anger among those who are older, or is it that the stress is being experienced by individuals who are less inclined to bad moods? "A negative mood set and depression are risk factors of death and mortality," said Adam Davey, a developmental psychologist at Temple. "As people who are sadder and more depressed select out of the population, those who are left are generally happier and more content."