Illustration Credits

All illustrations are courtesy of the authors, with the exception of the following:

Adapted from Laumann and others, The Social Organization of Sexuality: Sexual Practices in the United States (Chicago: University of Chicago Press, 1994), 235.

Adapted from P. S. Bearman, J. Moody, and K. Stovel, “Chains of Affection,” American Journal of Sociology 110 (2004): 44–91.

Adapted from J. J. Potterat and others, “Sexual Network Structure as an Indicator of Epidemic Phase,” Sexually Transmitted Infections 78 (2002): 152–58.

Courtesy of C. Mamali, “Participative Pictorial Representations of Self-Other Relationships: Social-Autograph Method,” paper presented at the General Meeting of the European Association of Experimental Social Pyschology, Croatia, June 1–14, 2008.

Plate 1: Reprinted from J. H. Fowler and N. A. Christakis, “Dynamic Spread of Happiness in a Large Social Network,” British Medical Journal 337 (2008): a2338.

Plate 3: Reprinted from N. A. Christakis and J. H. Fowler, “The Spread of Obesity in a Large Social Network Over 32 Years,” New England Journal of Medicine 357 (2007): 370–79.

Plate 4: Reprinted from N. A. Christakis and J. H. Fowler, “The Collective Dynamics of Smoking in a Large Social Network,” New England Journal of Medicine 358 (2008): 2249–58.

Plate 5: Adapted from M. Kearns, S. Suri, and N. Montfort, “An Experimental Study of the Coloring Problem on Human Subject Networks,” Science 313 (2006): 824–27.

Plate 6: Reprinted with permission from L. A. Adamic and N. Glance, “The Political Blogosphere and the 2004 U.S. Election: Divided They Blog,” Proceedings of the 3rd International Workshop on Link Discovery (New York: Association for Computing Machinery, 2005): 37.

Plate 7: Reprinted from J. Kelly and B. Etling, “Mapping Iran’s Online Public,” Berkman Center Research Publication 2008–01 (2008): 1–36.