Today's "Well, duh!" research:
A new study suggests that lonely people attract fellow "lonelies" and influence others to feel lonely, too.
"Loneliness can spread from person to person to person -- up to three degrees of separation," said James H. Fowler, co-author of the study published in the December issue of the Journal of Personality and Social Psychology, and professor of political science at the University of California, San Diego.
Indeed, the study suggests that not only is loneliness contagious, but lonely people tend to isolate themselves in small groups that somehow compound or increase those feelings of solitude.
Do you suppose the opposite could possibly also be true, that gregariousness is catching, that not only do happy people make other people happy but also tend to segregate themselves into groups of happy people? We don't have the research on that yet, so better not say it too confidently.