A recent study suggests that dogs actually can tell the difference when people are sad or happy, and that they’ll more often approach a person crying rather than someone who is joyfully humming.  The study was published in the May 30 journal Animal Cognition, and researchers said that while the dogs’ behavior may indicate that they understand when a human is in pain, they could offer no solid proof that was the case.  One researcher, Deborah Custance, said that the dogs’ different responses to crying and humming wasn’t solely driven by curiosity.  “The crying carried greater emotional meaning and provoked a stronger overall response,” she said.   The studies were carried out in the homes of 18 dogs and their guardians, with the breeds including mutts, Labs, Goldens and others.  Read more here.