A baby’s first smiles are not likely an expression of inner emotion but “first smiles teach infants the positive associations attached to a smile that we adults already feel,” says one professor of psychology. “Daniel Messinger, a professor of psychology at the University of Miami, suspects that learning to smile—and learning what’s meant by a smile—is a process, much like learning how to walk. ‘I take smiling to be a social signal,’ Messinger says. ‘I really think that babies are learning what joy is by sharing it with someone else.’ In other words, smiling might not be so much an expression of a preexisting state as a path we take to get to that state.”