Credit: James Fowler, UC San Diego
Happiness in a social network: The graph shows the largest component of friends, spouses and siblings in 2000. Circles are females, squares are males and the lines between them indicate relationships (black for siblings, red for friends and spouses). Colors show the average happiness of a person and all of his or her social relations, with blue for sad, yellow for happy and shades of green for inbetween.