Notes

CHAPTER 1: IN THE THICK OF IT

 1. R. V. Gould, “Revenge as Sanction and Solidarity Display: An Analysis of Vendettas in Nineteenth-Century Corsica,” American Sociological Review 65 (2000): 682–704.

 2. B. A. Jacobs, “A Typology of Street Criminal Retaliation,” Journal of Research in Crime and Delinquency 41 (2004): 295–323.

 3. A. V. Papachristos, “Murder by Structure: Dominance Relations and the Social Structure of Gang Homicide in Chicago,” December 2007, http://ssrn.com/abstract=855304.

 4. M. Planty, Third Party Involvement in Violent Crime, 1993–1999 (Washington, DC: Bureau of Justice Statistics Special Report, 2002).

 5. www.livingdonorsonline.com (accessed October 3, 2008).

 6. “Walk Strikes Close to Home for Organ Donor’s Family,” The Mississauga News, April 28, 2008.

 7. M. A. Rees and others, “A Nonsimultaneous, Extended, Altruistic-Donor Chain,” New England Journal of Medicine 360 (2009): 1096–1101.

 8. “ ‘Moon Tracking’ Station Readied at Canoga Park,” Los Angeles Times, November 25, 1957.

 9. P. Marsden, “Core Discussion Networks of Americans,” American Sociological Review 52 (1987): 122–31; see also: M. McPherson and others, “Social Isolation in America: Changes in Core Discussion Networks Over Two Decades,” American Sociological Review 71 (2006): 353–75.

10. I. de Sola Pool and M. Kochen, “Contacts and Influence,” Social Networks 1 (1978/1979): 5–51.

11. P. Kristensen and T. Bjerkedal, “Explaining the Relation Between Birth Order and Intelligence,” Science 316 (2007): 1717.

12. S. Milgram, L. Bickman, and L. Berkowitz, “Note on the Drawing Power of Crowds of Different Size,” Journal of Personality and Social Psychology 13 (1969): 79–82.

13. I. Farkas and others, “Mexican Waves in an Excitable Medium,” Nature 419 (2002): 131–32.

14. I. D. Couzin and others, “Effective Leadership and Decision-Making in Animal Groups on the Move,” Nature 433 (2005): 513–16.

15. J. Travers and S. Milgram, “An Experimental Study in the Small World Problem,” Sociometry 35, no. 4 (1969): 425–43.

16. P. S. Dodds and others, “An Experimental Study of Search in Global Social Networks,” Science 301 (2003): 827–29.

CHAPTER 2: WHEN YOU SMILE, THE WORLD SMILES WITH YOU

 1. A. M. Rankin and P. J. Philip, “An Epidemic of Laughing in the Bukoba District of Tanganyika,” Central African Journal of Medicine 9 (1963): 167–70.

 2. A. Hatfield and others, “Emotional Contagion,” Current Directions in Psychological Science 2 (1993): 96–99.

 3. C. N. Scollon and others, “Experience Sampling: Promise and Pitfalls, Strengths and Weaknesses,” Journal of Happiness Studies 4 (2003): 5–34; J. P. Laurenceau and N. Bolger, “Using Diary Methods to Study Marital and Family Processes,” Journal of Family Psychology 19 (2005): 86–97; R. Larson and M. H. Richards, Divergent Realities: The Emotional Lives of Mothers, Fathers, and Adolescents (New York: Basic Books, 1994).

 4. M. J. Howes and others, “Induction of Depressive Affect After Prolonged Exposure to a Mildly Depressed Individual,” Journal of Personality and Social Psychology 49 (1985): 1110–13.

 5. S. D. Pugh, “Service with a Smile: Emotional Contagion in the Service Encounter,” Academy of Management Journal 44 (2001): 1018–27; W. C. Tsai and Y. M. Huang, “Mechanisms Linking Employee Affective Delivery and Customer Behavioral Intentions,” Journal of Applied Psychology 87 (2002):1001–8.

 6. J. B. Silk, “Social Components of Fitness in Primate Groups.” Science 317 (2007): 1347–51.

 7. J. M. Susskind and others, “Expressing Fear Enhances Sensory Acquisition,” Nature Neuroscience 11 (2008): 843–50.

 8. Cited in Hatfield, “Emotional Contagion,” 97.

 9. M. Iacoboni, Mirroring People: The New Science of How We Connect with Others (New York: Farrar, Straus, and Giroux, 2008).

10. J. E. Warren and others, “Positive Emotions Preferentially Engage an Auditory-Motor ‘Mirror’ System,” Journal of Neuroscience 26 (2006): 13067–75.

11. J. F. C. Hecker, The Epidemics of the Middle Ages, trans. by B. G. Babington (London: Sydenham Society, 1844), 87–88.

12. T. F. Jones and others, “Mass Psychogenic Illness Attributed to Toxic Exposure at a High School,” New England Journal of Medicine 342 (2000): 96–100.

13. “Mass Hysteria Can Make Many Sick—Tennessee Case Shows How Anxiety Spreads,” Florida Times-Union, May 7, 2000.

14. Jones, “Mass Psychogenic Illness,” 100.

15. L. P. Boss, “Epidemic Hysteria: A Review of the Published Literature,” Epidemiological Reviews 19 (1997): 233–43.

16. D. M. Johnson, “The ‘Phantom Anesthetist’ of Mattoon: A Field Study of Mass Hysteria,’ in Readings in Social Psychology (New York: Henry Holt and Co., 1952), 210.

17. E. T. Rolls, “The Functions of the Orbitofrontal Cortex,” Brain and Cognition 55 (2004): 11–29.

18. J. Willander and M. Larsson, “Olfaction and Emotion: The Case of Autobiographical Memory,” Memory and Cognition 35 (2007): 1659–63.

19. R. S. Herz and others, “Neuroimaging Evidence for the Emotional Potency of Odor-Evoked Memory,” Neuropsychologia 42 (2004): 371–78; D. H. Zald and J. V. Pardo, “Emotion, Olfaction, and the Human Amygdala: Amygdala Activation During Aversive Olfactory Stimulation,” Proceedings of the National Academy of Sciences 94 (1997): 4119–24.

20. Boss, “Epidemic Hysteria,” 238.

21. M. Talbot, “Hysteria Hysteria,” New York Times, June 2, 2002.

22. N. A. Christakis, “This Allergies Hysteria Is Just Nuts,” British Medical Journal 337 (2008): a2880.

23. M. Csikszentmihalyi and R. Larson, “Validity and Reliability of the Experience-Sampling Method,” Journal of Nervous and Mental Diseases 175 (1987): 527; M. Csikszentmihalyi and others, “The Ecology of Adolescent Activity and Experience,” Journal of Youth and Adolescence 6 (1977): 281–94.

24. R. W. Larson and M. H. Richards, “Family Emotions: Do Young Adolescents and Their Parents Experience the Same States?” Journal of Research on Adolescence 4 (1994): 567–83.

25. P. Totterdell, “Catching Moods and Hitting Runs: Mood Linkage and Subjective Performance in Professional Sports Teams,” Journal of Applied Psychology 85 (2000): 848–59.

26. J. H. Fowler and N. A. Christakis, “Dynamic Spread of Happiness in a Large Social Network: Longitudinal Analysis Over 20 Years in the Framingham Heart Study,” British Medical Journal 337 (2008): a2338.

27. R. A. Easterlin, “Explaining Happiness,” Proceedings of the National Academy of Sciences 100 (2003): 11176–83.

28. J. Knight and R. Gunatilaka, “Is Happiness Infections?” (unpublished paper, Oxford University, 2009).

29. E. Diener, R. E. Lucas, and C. N. Scollon, “Beyond the Hedonic Treadmill: Revising the Adaptation Theory of Well-Being,” American Psychologist 61 (2006): 305–14.

30. D. Gilbert, Stumbling on Happiness (New York: Vintage, 2005).

31. S. Lyubormirsky and others, “Pursuing Happiness: The Architecture of Sustainable Change,” Review of General Psychology 9 (2005): 111–31.

32. J. M. Ernst and J. T. Cacioppo, “Lonely Hearts: Psychological Perspectives on Loneliness,” Applied and Preventive Psychology 8, no. 1 (1999): 1–22.

33. J. T. Cacioppo, J. H. Fowler, and N. A. Christakis, “Alone in the Crowd: The Structure and Spread of Loneliness in a Large Social Network,” Journal of Personality and Social Psychology (forthcoming).

34. H. Fisher, Why We Love: The Nature and Chemistry of Romantic Love (New York: Henry Holt and Co., 2004).

CHAPTER 3: LOVE THE ONE YOU’RE WITH

 1. http://www.city-data.com/forum/relationships/331411-how-i-met-my-spouse-3.html (accessed March 3, 2009). Reprinted by permission of the author.

 2. E. O. Laumann and others, The Social Organization of Sexuality: Sexual Practices in the United States (Chicago: University of Chicago Press, 1994).

 3. M. Bozon and F. Héran, “Finding a Spouse: A Survey of How French Couples Meet,” Population 44, no. 1 (1989): 91–121.

 4. Laumann, Social Organization of Sexuality.

 5. Bozon, “Finding a Spouse.”

 6. M. Madden and A. Lenhart, “Online Dating,” Pew Internet and American Life Project, http://www.pewinternet.org/pdfs/PIP_Online_Dating.pdf, ii (accessed February 28, 2009).

 7. Ibid.

 8. Ibid., iii.

 9. X. Xiaohe and M. K. Whyte, “Love Matches and Arranged Marriage: A Chinese Replication,” Journal of Marriage and Family 52 (1990): 709–22; see also N. P. Medora, “Mate Selection in Contemporary India: Love Marriages Versus Arranged Marriages,” in Mate Selection Across Cultures, ed. H. R. Hamon and B. B. Ingoldsby (Thousand Oaks, CA: Sage Publications, 2003): 209–30.

10. Laumann, Social Organization of Sexuality, 255.

11. J. K. Galbraith, The Affluent Society (Boston, MA: Houghton Mifflin, 1958).

12. A. Tverksy and D. Griffin, Strategy and Choice (Cambridge, MA: Harvard University Press, 1991).

13. S. J. Solnick and D. Hemenway, “Is More Always Better? A Survey on Positional Concerns,” Journal of Economic Behavior and Organization 37 (1998): 373–83.

14. L. Jin and others, “Reduction in Long-Term Survival in Men Given High Operational Sex Ratio at Sexual Maturity,” Demography (forthcoming).

15. R. K. Merton, Social Theory and Social Structure (New York: Free Press of Glencoe, 1957); R. K. Merton and A. S. Kitt, “Contributions to the Theory of Reference Group Behavior,” in Continuities in Social Research: Studies in the Scope and Method of “The American Soldier,” ed. R. K. Merton and P. F. Lazarsfeld (Glencoe, IL: Free Press, 1950), 40–105; A. Bandura, Social Learning Theory (New York: General Learning Press, 1971); L. Festinger, “A Theory of Social Comparison Processes,” Human Relations 7 (1954): 117–40.

16. B. C. Jones and others, “Social Transmission of Face Preferences Among Humans,” Proceedings of the Royal Society B 274 (2007): 899–903.

17. K. Eva and T. Wood, “Are All The Taken Men Good? An Indirect Examination of Mate-Choice Copying in Humans,” Canadian Medical Association Journal 175 (2006): 1573–74.

18. D. Waynforth, “Mate Choice Copying in Humans,” Human Nature 18 (2007): 264–71.

19. P. Bressan and D. Stranieri, “The Best Men Are (Not Always) Already Taken: Female Preference for Single Versus Attached Males Depends on Conception Risk,” Pyschological Science 19 (2008): 145–51.

20. D. T. Gilbert and others, “The Surprising Power of Neighborly Advice,” Science 323 (2009): 1617–19.

21. S. E. Hill and D. M. Buss, “The Mere Presence of Opposite-Sex Others on Judgments of Sexual and Romantic Desirability: Opposite Effects for Men and Women,” Personality and Social Psychology Bulletin 34 (2008): 635–47.

22. M. D. Regnerus and L. B. Luchies, “The Parent-Child Relationship and Opportunities for Adolescents’ First Sex,” Journal of Family Issues 27 (2006): 159–83.

23. S. E. Cavanagh, “The Sexual Debut of Girls in Early Adolescence: The Intersection of Race, Pubertal Timing, and Friendship Group Characteristics,” Journal of Research on Adolescence 14 (2004): 285–312.

24. A. Adamczyk and J. Felson, “Friends’ Religiosity and First Sex,” Social Science Research 35 (2006): 924–47.

25. P. S. Bearman and H. Brückner, “Promising the Future: Abstinence Pledges and the Transition to First Intercourse,” American Journal of Sociology 106 (2001): 859–912.

26. W. Manning, M. A. Longmore, and P. C. Giordano, “Adolescents’ Involvement in Non-Romantic Sexual Activity,” Social Science Research 34 (2005): 384–407.

27. M. J. Prinstein, C. S. Meade, and G. L. Cohen, “Adolescent Oral Sex, Peer Popularity, and Perceptions of Best Friend’s Sexual Behavior,” Journal of Pediatric Psychology 28 (2003): 243–49.

28. Laumann, Social Organization of Sexuality.

29. I. Kuziemko, “Is Having Babies Contagious? Estimating Fertility Peer Effects Between Siblings,” http://www.princeton.edu/~Ekuziemko/fertility_11_29_06.pdf (accessed March 1, 2009).

30. D. E. Bloom and others, “Social Interactions and Fertility in Developing Countries,” PGDA Working Paper 34 (2008).

31. W. Farr, “Influence of Marriage on the Mortality of the French People,” in Transactions of the National Association for the Promotion of Social Science, ed. G. W. Hastings (London: John W. Park & Son, 1858), 504–13.

32. D. Lubach, quoted in F. Van Poppel and I. Joung, “Long Term Trends in Marital Status Differences in the Netherlands 1850–1970,” Journal of Biosocial Science 33 (2001): 279–303.

33. B. Turksma, quoted in Van Poppel and I. Joung, “Long Term Trends in Marital Status Differences in the Netherlands 1850–1970,” Journal of Biosocial Science 33 (2001): 279–303.

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35. F. Elwert and N. A. Christakis, “Variation in the Effect of Widowhood on Mortality by the Causes of Death of Both Spouses,” American Journal of Public Health 98 (2008): 2092–98.

36. L. J. Waite, “Does Marriage Matter?” Demography 32 (1995): 483–508.

37. L. A. Lillard and L. J. Waite, “ Til Death Do Us Part—Marital Disruption and Mortality,” American Journal of Sociology 100 (1995): 1131–56; L. A. Lillard and C. A. W. Panis, “Marital Status and Mortality: The Role of Health,” Demography 33 (1996): 313–27.

38. See, for example: K. Allen, J. Blascovich, W. B. Mendes, “Cardiovascular Reactivity and the Presence of Pets, Friends, and Spouses: The Truth about Cats and Dogs,” Psychosomatic Medicine 64 (2002): 727–39; J. K. Kiecolt-Glaser and others, “Marital Quality, Marital Disruption, and Immune Function,” Psychosomatic Medicine 49 (1987): 13–34.

39. T. J. Iwashyna and N. A. Christakis, “Marriage, Widowhood, and Health Care Use,” Social Science and Medicine 57 (2003): 2137–47; L. Jin and N. A. Christakis, “Investigating the Mechanism of Marital Mortality Reduction: The Transition to Widowhood and Quality of Health Care,” Demography (forthcoming).

40. D. Umberson, “Family Status and Health Behaviors: Social Control as a Dimension of Social Integration,” Journal of Health and Social Behavior 28 (1987): 306–19; D. Umberson, “Gender, Marital Status and the Social Control of Health Behavior,” Social Science and Medicine 34 (1992): 907–17.

41. F. Elwert and N. A. Christakis, “Widowhood and Race,” American Sociological Review 71 (2006): 16–41.

42. See, for example, ibid.

43. Y. Hu and N. Goldman, “Mortality Differentials by Marital Status: An International Comparison,” Demography 27 (1990): 233–50.

44. Elwert, “Widowhood and Race.”

45. D. Umberson and others, “You Make Me Sick: Marital Quality and Health Over the Life Course,” Journal of Health and Social Behavior 47 (2006): 1–16; see also D. Carr, “Gender, Pre-loss Marital Dependence, and Older Adults’ Adjustment to Widowhood,” Journal of Marriage and Family 66 (2004): 220–35.

46. G. Clark, Too Brief a Treat—Letters of Truman Capote (New York: Random House, 2004).

CHAPTER 4: THIS HURTS ME AS MUCH AS IT HURTS YOU

 1. http://www.rockdalecounty.org/main.cfm?id=2130 (accessed March 1, 2009).

 2. M. A. J. McKenna, “Teen Sex Tales Turn National Focus to Rockdale,” Atlanta Journal-Constitution, October 19, 1999; see also R. B. Rothenberg and others, “Using Social Network and Ethnographic Tools to Evaluate Syphilis Transmission,” Sexually Transmitted Diseases 25 (1998): 154–60.

 3. McKenna, “Teen Sex Tales.”

 4. C. Russell, “Venereal Disease Rampant Among America’s Teenagers; Health Officials Call for Prevention and Study,” Washington Post, November 26, 1996.

 5. McKenna, “Teen Sex Tales.”

 6. Rothenberg, “Using Social Network and Ethnographic Tools.”

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

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

 9. E. O. Laumann and Y. Youm, “Racial/Ethnic Group Differences in the Prevalence of Sexually Transmitted Diseases in the United States: A Network Explanation,” Sexually Transmitted Diseases 26 (1999): 250–61.

10. F. Liljeros and others, “The Web of Human Sexual Contacts,” Nature 411 (2001): 908–9.

11. S. Helleringer and H. P. Kohler, “Sexual Network Structure and the Spread of HIV in Africa: Evidence from Likoma Island, Malawi,” AIDS 21 (2007): 2323–32.

12. H Epstein, The Invisible Cure: Africa, the West, and the Fight Against AIDS (New York: Farrar, Straus, and Giroux, 2007).

13. B. Wansink, Mindless Eating: Why We Eat More Than We Think (New York: Bantam, 2006); V. I. Clendenen, C. P. Herman, and J. Polivy, “Social Facilitation of Eating among Friends and Strangers,” Appetite 23 (1994): 1–13.

14. 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.

15. J. H. Fowler and N. A. Christakis, “Estimating Peer Effects on Health in Social Networks,” Journal of Health Economics 27(2008): 1386–91.

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25. A. R. Lucas and others, “50-Year Trends in the Incidence of Anorexia Nervosa in Rochester, Minn.: A Population-Based Study,” American Journal of Psychiatry 148 (1991): 917–22; American Psychiatric Association Work Group on Eating Disorders, “Practice Guideline for the Treatment of Patients with Eating Disorders,” American Journal of Psychiatry 157 (2000): 1–39.

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34. See, for example: UPI, “Japanese Internet Suicide Clubs Targeted by Police,” October 7, 2005; BBC News, “Nine Die in Japan Suicide Pacts,” October 12, 2004; and S. Rajagopal, “Suicide Pacts and the Internet,” British Medical Journal 329 (2004): 1298–99.

35. P. S. Bearman and J. Moody, “Suicide and Friendships Among American Adolescents,” American Journal of Public Health 94 (2004): 89–95.

36. P. Hedstrom, K. Y. Liu, and M. K. Nordvik, “Interaction Domains and Suicides: A Population-Based Panel Study of Suicides in Stockholm, 1991–1999,” Social Forces 87 (2008): 713–40.

37. M. D. Resnick and others, “Protecting Adolescents from Harm: Findings from the National Longitudinal Study of Adolescent Health,” Journal of the American Medical Association 278 (1997): 823–32.

38. Centers for Disease Control, “Suicide Contagion.”

39. M. Gould, P. Jamieson, and D. Romer, “Media Contagion and Suicide Among the Young,” American Behavioral Scientist 46 (2003): 1269–84.

40. R. R. Wing and R. W. Jeffery, “Benefits of Recruiting Participants with Friends and Increasing Social Support for Weight Loss and Maintenance,” Journal of Consulting and Clinical Psychology 67 (1999): 132–38.

41. A. A. Gorin and others, “Weight Loss Treatment Influences Untreated Spouses and the Home Environment: Evidence of a Ripple Effect,” International Journal of Obesity 32 (2008): 1678–84; see also A. L. Shattuck, E. White, A. R. Kristal, “How Women’s Adopted Low-Fat Diets Affect Their Husbands,” American Journal of Public Health 82 (1992): 1244–50; R. S. Zimmerman and others, “The Effects of a Worksite Health Promotion Program on the Wives of Firefighters,” Social Science and Medicine 26 (1988): 537–43.

42. T. W. Valente and P. Pumpuang, “Identifying Opinion Leaders to Promote Behavior Change,” Health Education and Behavior 34 (2007): 881–96.

43. D. B. Buller and others, “Randomized Trial Testing the Effect of Peer Education in Increasing Fruit and Vegetable Intake,” Journal of the National Cancer Institute 91 (1999):1491–1500; K. J. Sikkema and others, “Outcomes of a Randomized Community-Level HIV Prevention Intervention for Women Living in 18 Low-Income Housing Developments,” American Journal of Public Health 90 (2000): 57–63.

44. D. J. Watts and P. S. Dodds, “Influentials, Networks, and Public Opinion Formation,” Journal of Consumer Research 34 (2007): 441–58.

45. D. Bahr and others, “Exploiting Social Networks to Mitigate the Obesity Epidemic,” Obesity 17 (2009): 723–28.

46. R. Cohen, S. Havlin, and D. Aen-Avraham, “Efficient Immunization Strategies for Computer Networks and Populations,” Physical Review Letters 91 (2003): 247901.

47. J. Leskovec and others, “Cost-Effective Outbreak Detection in Networks,” in Proceedings of the 13th ACM SIGKDD International Conference on Knowledge Discovery and Data Mining (New York: Association for Computing Machinery, 2007), 420–29.

CHAPTER 5: THE BUCK STARTS HERE

 1. P. Trowbridge and S. Thompson, “Northern Rock Experiences Second Day of Withdrawals,” Bloomberg, September 15, 2007.

 2. Ibid.

 3. “Panic Grips Northern Rock Savers for Second Straight Day,” AFP, September 13, 2007.

 4. B. Livesey and J. Menon, “Northern Rock Stock Tumbles Further Amid Run on Bank,” Bloomberg, September 17, 2007.

 5. “The Great Northern Run,” Economist, September 20, 2007.

 6. M. Oliver, “Customers Rush to Withdraw Money,” Guardian, September 14, 2007.

 7. J. Werdigier, “A Rush to Cash out of Northern Rock,” International Herald Tribune, September 17, 2007.

 8. D. Segal, “In Letter, Buffet Accepts Blame and Faults Others,” New York Times, March 1, 2009.

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10. M. Grabell, “Dallas: Venue Closing for 5 Months After Prostitution Arrests,” Dallas Morning News, February 6, 2007.

11. S. Scott and C. Duncan, Biology of Plagues: Evidence from Historical Populations (Cambridge: Cambridge University Press, 2001).

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14. R. Shiller, Irrational Exuberance (Princeton, NJ: Princeton University Press, 2005).

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33. M. Yunus, Banker to the Poor: Micro-Lending and the Battle Against World Poverty (New York: Public Affairs, 2003), 62.

34. C. Geertz, “The Rotating Credit Association: A ‘Middle Rung’ in Development,” Economic Development and Cultural Change 10 (1962): 241–63.

35. T. Besley, S. Coate, and G. Loury, “The Economics of Rotating Savings and Credit Associations,” American Economic Review 83 (1993): 792–810; S. Ardner, “The Comparative Study of Rotating Credit Associations,” Journal of the Royal Anthropological Institute 94 (1964): 202–29.

CHAPTER 6: POLITICALLY CONNECTED

 1. A. Smith and L. Raine, “The Internet and the 2008 Election,” June 15, 2008, http://www.pewinternet.org/~/media//Files/Reports/2008/PIP_2008_election.pdf (accessed April 4, 2009).

 2. A. Downs, An Economic Theory of Democracy (New York: Harper, 1957).

 3. W. Riker and P. Ordeshook, “A Theory of the Calculus of Voting,” American Political Science Review 62 (1968): 25–42.

 4. A. J. Fischer, “The Probability of Being Decisive,” Public Choice 101 (1999): 267–83; I. J. Good and L. S. Mayer, “Estimating the Efficacy of a Vote,” Behavioral Science 20 (1975): 25–33; G. Tullock, Towards a Mathematics of Politics (Ann Arbor, MI: University of Michigan, 1967).

 5. C. B. Mulligan and C. G. Hunter, “The Empirical Frequency of a Pivotal Vote,” Public Choice 116 (2003): 31–54.

 6. A. Gelman, G. King, and J. Boscardin, “Estimating the Probability of Events That Have Never Occurred: When Is Your Vote Decisive?” Journal of the American Statistical Association 93 (1998): 1–9.

 7. A. Blais and R. Young, “Why Do People Vote? An Experiment in Rationality,” Public Choice 99 (1999): 1–2, 39–55.

 8. T. Carpenter, “Professor Registers to Vote,” Lawrence Journal-World, November 12, 1996.

 9. M. Fiorina, “Information and Rationality in Elections,” in Information and Democratic Processes, ed. J. Ferejohn and J. Kuklinski (Urbana, IL: University of Illinois Press, 1990): 329–42.

10. A. Campbell, G. Gurin, and W. E. Miller, The Voter Decides (Evanston, IL: Row, Peterson and Company, 1954); W. A. Glaser, “The Family and Voting Turnout,” Public Opinion Quarterly 23 (1959): 563–70; B. C. Straits, “The Social Context of Voter Turnout,” Public Opinion Quarterly 54 (1990): 64–73; S. Knack, “Civic Norms, Social Sanctions, and Voter Turnout,” Rationality and Society 4 (1992): 133–56; C. B. Kenny, “Political Participation and Effects from the Social Environment,” American Journal of Political Science 36 (1992): 259–67; C. B. Kenny, “The Microenvironment of Political Participation,” American Politics Quarterly 21 (1993): 223–38; P. A. Beck and others, “The Social Calculus of Voting: Interpersonal, Media, and Organizational Influences on Presidential Choices,” American Political Science Review 96 (2002): 57–74.

11. P. F. Lazarsfeld, B. Berelson, and H. Gaudet, The People’s Choice (New York: Columbia University, 1944); B. Berelson, P. F. Lazarsfeld, and W. N. McPhee, Voting (Chicago: University of Chicago Press, 1954).

12. R. Huckfeldt and J. Sprague, Citizens, Parties, and Social Communication (New York: Cambridge University Press, 1995).

13. R. Huckfeldt, “Political Loyalties and Social Class Ties: The Mechanisms of Contextual Influence,” American Journal of Political Science 28 (1984): 414.

14. R. Huckfeldt, P. E. Johnson, and J. D. Sprague, Political Disagreement: The Survival of Diverse Opinions within Communication Networks (New York: Cambridge University Press, 2004).

15. J. H. Fowler, “Turnout in a Small World,” in The Social Logic of Politics: Personal Networks as Contexts for Political Behavior, ed. A. Zuckerman (Philadelphia: Temple University Press, 2005): 269–87.

16. R. Putnam, Bowling Alone (New York: Simon and Schuster, 2001).

17. D. W. Nickerson, “Is Voting Contagious? Evidence from Two Field Experiemtns,” American Political Science Review 102 (2008): 49–57.

18. A. de Tocqueville, Democracy in America, trans. and ed. H. C. Mansfield and D. Winthrop (Chicago: University of Chicago Press, 2000).

19. B. C. Burden, “Voter Turnout and the National Election Studies,” Political Analysis 8 (2000): 389–98.

20. K. T. Poole and H. Rosenthal, Congress: A Political-Economic History of Roll Call Voting (New York: Oxford University Press, 1997).

21. Congressional Record (Senate), September 11, 2006, S9297.

22. J. H. Fowler, “Legislative Cosponsorship Networks in the U.S. House and Senate,” Social Networks 28 (2006): 454–65; J. H. Fowler, “Connecting the Congress: A Study of Cosponsorship Networks,” Political Analysis 14 (2006): 456–87.

23. “Brazen Conspiracy,” Washington Post, November 29, 2005.

24. Y. Zhang and others, “Community Structure in Congressional Networks,” Physica A 387 (2008): 1705–12.

25. M. McGrory, “McCain, Gramm a Strange Pairing,” Omaha World Herald, November 18, 1995.

26. J. Zengerle, “Clubbed,” New Republic, May 7, 2001.

27. R. L. Hall, “Measuring Legislative Influence,” Legislative Studies Quarterly 17 (1992): 205–31; B. Sinclair, The Transformation of the U.S. Senate (Baltimore, MD: Johns Hopkins University, 1989); S. Smith, Call to Order (Washington, DC: Brookings Institution, 1989); B. Weingast, “Fighting Fire with Fire: Amending Activity and Institutional Change in the Postreform Congress,” in The Post-Reform Congress, ed. R. Davidson (New York: St. Martin’s Press, 1991).

28. D. P. Carpenter, K. M. Esterling, and D. M. J. Lazer, “Friends, Brokers, and Transitivity: Who Informs Whom in Washington Politics?” Journal of Politics 66 (2004): 224–46; D. P. Carpenter, K. M. Esterling, and D. M. J. Lazer, “The Strength of Weak Ties in Lobbying Networks—Evidence from Health-Care Politics in the United States,” Journal of Theoretical Politics 10 (1998): 417–44.

29. A. Hoffman, Steal This Book (New York: Grove Press, 1971).

30. M. T. Heaney and F. Rojas, “Partisans, Nonpartisans, and the Antiwar Movement in the United States,” American Politics Research 35 (2007): 431–64.

31. Smith and Raine, “The Internet and the 2008 Election.”

32. See, for example: L. A. Henao, “Columbians Tell FARC: ‘Enough’s enough’—In a March Organized on Facebook, Hundreds of Thousands Protested Against the Leftist Rebel Group Monday,” Christian Science Monitor, February 6, 2008.

33. 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), 36–43.

34. J. Kelly and B. Etling, “Mapping Iran’s Online Public: Politics and Culture in the Persian Blogosphere,” Berkman Center Research Publication 2008-01 (2008): 1–36.

35. Kelly and Etling, “Mapping,” 6.

CHAPTER 7: IT’S IN OUR NATURE

 1. “Survivor Recaps,” http://www.cbs.com/primetime/survivor/recaps/?season=2 (accessed March 5, 2009).

 2. B. Holldobler and E. O. Wilson, The Superorganism: The Beauty, Elegance, and Strangeness of Insect Societies (New York: W. W. Norton, 2009).

 3. I. McEwan, Enduring Love (New York: Anchor Books, 1998).

 4. R. Axelrod, The Evolution Corporation (New York: Basic Books, 1984).

 5. C. Hauert and others, “Volunteering as Red Queen Mechanism for Cooperation in Public Goods Games,” Science 296 (2002): 1129–32.

 6. R. Boyd and P. J. Richardson, “Punishment Allows the Evolution of Cooperation (or Anything Else) in Sizable Groups,” Ethology and Sociobiology 13 (1992): 171–95.

 7. J. H. Fowler, “Altruistic Punishment and the Origin of Cooperation,” Proceedings of the National Academy of Sciences 102 (2005): 7047–49.

 8. C. Hauert and others, “Via Freedom to Coercion: The Emergence of Costly Punishment,” Science 316 (2007): 1905–7.

 9. J. S. Mill, Essays on Some Unsettled Questions of Political Economy (London: Longmans, Green, Reader, and Dyer, 1874): V.46.

10. W. Güth, R. Schmittberger, and B. Schwarze, “An Experimental Analysis of Ultimatum Bargaining,” Journal of Economic Behavior and Organization 3 (1982): 367–88.

11. J. H. Fowler, “Altruism and Turnout,” Journal of Politics 68 (2006): 674–83; J. H. Fowler and C. D. Kam, “Beyond the Self: Altruism, Social Identity, and Political Participation,” Journal of Politics 69 (2007): 813–27; C. D. Kam, S. Cranmer, and J. H. Fowler, “When It’s Not All About Me: Altruism, Participation, and Political Context” (unpublished paper); C. T. Dawes, P. J. Loewen, and J. H. Fowler, “Social Preferences and Political Participation” (unpublished paper).

12. “Cash Found in House’s Walls Becomes Nightmare,” Associated Press, November 8, 2008.

13. R. Frank, T. Gilovich, and D. Regan, “Does Studying Economics Inhibit Cooperation?” Journal of Economic Perspectives 7 (1993): 159–71.

14. J. Henrich, “Does Culture Matter in Economic Behavior? Ultimatum Game Bargaining Among the Machiguenga,” American Economic Review 90 (2000): 973–79.

15. H. Xian and others, “Self-Reported Zygosity and the Equal-Environments Assumption for Psychiatric Disorders in the Vietnam Era Twin Registry,” Behavior Genetics 30 (2000): 303–10; K. S. Kendler and others, “A Test of the Equal-Environment Assumption in Twin Studies of Psychiatric Illness,” Behavior Genetics 23 (1993): 21–27; S. Scarr and L. Carter-Saltzman, “Twin Method: Defense of a Critical Assumption,” Behavior Genetics 9 (1979): 527–42.

16. D. Cesarini and others, “Heritability of Cooperative Behavior in the Trust Game,” Proceedings of the National Academy of Sciences 105 (2008): 3721–26.

17. J. H. Fowler, C. T. Dawes, and N. A. Christakis, “Model of Genetic Variation in Human Social Networks,” PNAS: Proceedings of the National Academy of Sciences 106 (2009): 1720–24.

18. Worlds Collide Theory, http://www.urbandictionary.com/define.php?term=Worlds+Collide+Theory (accessed March 4, 2009).

19. D. I. Boomsma and others, “Genetic and Environmental Contributions to Loneliness in Adults: The Netherlands Twin Register Study,” Behavior Genetics 35 (2005): 745–52.

20. Ibid.

21. M. M. Lim and others, “Enhanced Partner Preference in a Promiscuous Species by Manipulating the Expression of a Single Gene,” Nature 429 (2004): 754–57.

22. A. Knafo and others, “Individual Differences in Allocation of Funds in the Dictator Game Associated with Length of the Arginine Vasopressin 1a Receptor Rs3 Promoter Region and Correlation Between Rs3 Length and Hippocampal mRNA,” Genes, Brain and Behavior 7 (2008): 266–75.

23. J. C. Flack and others, “Policing Stabilizes Construction of Social Niches in Primates,” Nature 439 (2006): 426–29.

24. K. Faust and J. Skvoretz, “Comparing Networks Across Space and Time, Size, and Species,” Sociological Methodology 32 (2002): 267–99.

25. J. H. Fowler and D. Schreiber, “Biology, Politics, and the Emerging Science of Human Nature,” Science 322 (2008): 912–14.

26. M. A. Changizi, Q. Zhang, and S. Shimojo, “Bare Skin, Blood and the Evolution of Primate Colour Vision,” Biology Letters 2 (2006): 217–21.

27. E. Herrmann and others, “Humans Have Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis,” Science 317 (2007): 1360–66.

28. 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.

29. N. Epley and others, “Creating Social Connection Through Inferential Reproduction: Loneliness and Perceived Agency in Gadgets, Gods, and Greyhounds,” Psychological Science 19 (2008): 114–20.

30. A. B. Newberg and others, “The Measurement of Regional Cerebral Blood Flow During the Complex Cognitive Task of Meditation: A Preliminary SPECT Study,” Psychiatry Research: Neuroimaging 106 (2001): 113–22; A. B. Newberg and others, “Cerebral Blood Flow During Meditative Prayer: Preliminary Findings and Methodological Issues,” Perceptual and Motor Skills 97 (2003): 625–30.

31. R. Dunbar, “Coevolution of Neocortex Size, Group Size, and Language in Humans,” Behavioral and Brain Sciences 16 (1993): 681–735.

CHAPTER 8: HYPERCONNECTED

 1. E. T. Lofgren and N. H. Fefferman, “The Untapped Potential of Virtual Game Worlds to Shed Light on Real World Epidemics,” Lancet Infectious Diseases 7 (2007): 625–29.

 2. S. Milgram, “Behavioral Study of Obedience,” Journal of Abnormal and Social Psychology 67 (1963): 371–78; S. Milgram, Obedience to Authority: An Experimental View (New York: Harper Collins, 1974).

 3. T. Blass, “The Milgram Paradigm After 35 years: Some Things We Now Know about Obedience to Authority,” Journal of Applied Social Psychology 29 (1999): 955–78.

 4. M. Slater and others, “A Virtual Reprise of the Stanley Milgram Obedience Experiments,” PLoS ONE 1, no. 1 (2006): e39. doi:10.1371/journal.pone.0000039.

 5. See, for example: A. Case, C. Paxson, and M. Islam, “Making Sense of the Labor Market Height Premium: Evidence from the British Household Panel Survey,” NBER Working Paper 14007, May 2008; D. Hamermesh and J. Biddle, “Beauty and the Labor Market,” American Economic Review 84 (1994): 1174–94; B. Harper, “Beauty, Stature and the Labour Market: A British Cohort Study,” Oxford Bulletin of Economics and Statistics 62 (2008): 771–800; E. Loh, “The Economic Effects of Physical Appearance,” Social Science Quarterly 74 (1993): 420–37.

 6. N. Yee and J. Bailenson, “The Proteus Effect: The Effect of Transformed Self-Representation on Behavior,” Human Communication Research 33 (2007): 271–90.

 7. Ibid.

 8. N. Yee, J. Bailenson, and N. Ducheneaut, “The Proteus Effect: Implications of Transformed Digital Self-Representation on Online and Offline Behavior,” Human Communication Research 36 (2009): 285–312.

 9. P. W. Eastwick and W. L. Garnder, “Is It a Game? Evidence for Social Influence in the Virtual World,” Social Influence 1 (2008): 1–15.

10. N. Yee and others, “The Unbearable Likeness of Being Digital: The Persistence of Nonverbal Social Norms in Online Virtual Environments,” CyberPyschology and Behavior 10 (2007): 115–21.

11. A. Cliff and P. Haggett, “Time, Travel, and Infection,” British Medical Bulletin 69 (2004): 87–99.

12. Ibid.

13. D. J. Bradley, “The Scope of Travel Medicine” in Travel Medicine: Proceedings of the First Conference on International Travel Medicine, ed. R. Steffen (Berlin: Springer-Verlag, 1989): 1–9.

14. M. C. Gonzalez, C. A. Hidalgo, and A. L. Barabási, “Understanding Individual Human Mobility Patterns,” Nature 453 (2008): 779–82.

15. T. Standage, The Victorian Internet (New York: Walker and Company, 1998).

16. I. de Sola Pool, Forecasting the Telephone: A Retrospective Technology Assessment of the Telephone (Norwood, NJ: Ablex Publishing, 1983): 86.

17. Ibid., 49.

18. C. S. Fischer, America Calling: A Social History of the Telephone to 1940 (Berkeley, CA: University of California Press, 1992): 26.

19. C. H. Cooley, quoted in R. McKenzie, “The Neighborhood,” reprinted in Rodrick D. McKenzie on Human Ecology, ed. A. Hawley (Chicago: University of Chicago Press, 1921 [1968]): 51–93.

20. Fischer, America Calling; M. Mayer, “The Telephone and the Uses of Time,” in The Social Impact of the Telephone, ed. I. de Sola Pool (Cambridge, MA: MIT Press, 1977), 225–45; N. S. Baron, Always On: Language in an Online and Mobile World (New York: Oxford University Press, 2008).

21. H. N. Casson, “The Social Value of the Telephone,” The Independent 71 (1911): 899.

22. K. Hampton, “Netville: Community On and Offline in a Wired Suburb,” in The Cybercities Reader, ed. S. Graham (London: Routledge, 2004): 260.

23. Hampton, “Netville,” 260.

24. D. M. Boyd and N. B. Ellison, “Social Network Sites: Definition, History, and Scholarship,” Journal of Computer-Mediated Communication 13 (2007): 210–30.

25. Ibid.

26. “Eliot Students Petition for Tape; Kirklanders Fast for Facebook,” Harvard Crimson, December 1, 1984.

27. S. C. Faludi, “Help Wanted: Brass Tacks,” Harvard Crimson, September 28, 1979.

28. “Facebook Statistics,” http://www.facebook.com/press/info.php?statistics (accessed March 7, 2009)

29. K. Lewis and others, “Tastes, Ties, and Time: A New (Cultural, Multiplex, and Longitudinal) Social Network Dataset Using Facebook.com,” Social Networks 30 (2008): 330–42.

30. The Colbert Report, July 31, 2006.

31. J. H. Fowler, “The Colbert Bump in Campaign Donations: More Truthful than Truthy,” PS: Political Science & Politics 41 (2008): 533–39.

32. A. Ebersbach and others, Wiki: Web Collaboration (New York: Springer-Verlag, 2008).

33. J. Giles, “Internet Encyclopaedias Go Head to Head,” Nature 438 (2005): 900–1.

34. “When Sam Met Allison,” Children’s News, September 2008.

35. “ACOR Acorlists,” http://www.acor.org/about/about.html (accessed March 7, 2009).

36. J. D. Klausner and others, “Tracing a Syphilis Outbreak Through Cyberspace,” Journal of the American Medical Association 284 (2000): 447–49.

37. A. Lenhart, L. Rainie, and O. Lewis, Teenage Life Online: The Rise of the Instant-Message Generation and the Internet’s Impact on Friendship and Family Relationships (Washington, DC: Pew Internet and American Life Project, 2001).

38. A. Lenhart, M. Madden, and P. Hitlin, Teens and Technology (Washington, DC: Pew Internet and American Life Project, 2005).

39. J. L. Whitlock, J. L. Powers, and J. Eckenrode, “The Virtual Cutting Edge: The Internet and Adolescent Self-Injury,” Developmental Psychology 42, no. 3 (2006): 1–11.

40. Ibid.

41. Ibid., 7.

42. http://gangstalkingworld.com (accessed November 6, 2008).

43. S. Kershaw, “Sharing Their Demons on the Web,” New York Times, November 12, 2008; see also V. Bell, A. Munoz-Solomando, and V. Reddy, “ ‘Mind Control’ Experiences on the Internet: Implications for Psychiatric Diagnosis or Delusions,” Psychopathology 39 (2006): 87–91.

44. “Woman Arrested for Killing Virtual Reality Husband,” CNN, October 23, 2008.

45. “Virtual World Affair Ends with Real-Life Divorce,” Western Morning News, November 14, 2008.

CHAPTER 9: THE WHOLE IS GREAT

 1. Genesis, 11: 6 (King James Version).

 2. T. Hobbes, The Leviathan, ed. M. Oakshott (Oxford: Oxford University Press, 1962): 100.

 3. B. Holldobler and E. O. Wilson, The Superorganism: The Beauty, Elegance, and Strangeness of Insect Societies (New York: W. W. Norton, 2009).

 4. M. Nowak, “Five Rules for the Evolution of Cooperation,” Science 314 (2006): 1560–63.

 5. I. D. Couzin and others, “Effective Leadership and Decision-Making in Animal Groups on the Move,” Nature 433 (2005): 513–16; I. D. Couzin and others, “Collective Memory and Spatial Sorting in Animal Groups,” Journal of Theoretical Biology 218 (2002): 1–11.

 6. D. P. Bebber and others, “Biological Solutions to Transport Network Design,” Proceedings of the Royal Society B 274 (2007): 2307–15; “Transport Efficiency and Resilience in Mycelial Networks,” remarks by Mark Fricker at the Meeting of the German Physical Society, Dresden, March 27, 2009.

 7. T. Nakagaki, H. Yamada, and A. Toth, “Maze-solving by an Amoeboid Organism,” Nature 407 (2000): 470.

 8. G. Palla, A. L. Barabási, and T. Vicsek, “Quantifying Social Group Evolution,” Nature 446 (2007): 664–67.

 9. S. Crabtree and B. Pelham, “Religion Provides Emotional Boost to World’s Poor,” March 6, 2009, http://www.gallup.com/poll/116449/Religion-Provides-Emotional-Boost-World-Poor.aspx.

10. E. L. Glaeser, B. Sacerdote, J. A. Scheinkman, “Crime and Social Interactions,” Quarterly Journal of Economics 11 (1996): 507–48.

11. A. J. Reiss, “Understanding Changes in Crime Rates,” in Indicators of Crime and Criminal Justice: Quantitative Studies, ed. S. Feinberg and A. J. Reiss (Washington, DC: Bureau of Justice Statistics, 1980).

12. F. Gino, S. Ayal, and D. Ariely, “Contagion and Differentiation in Unethical Behavior: The Effect of One Bad Apple on the Barrel,” Psychological Science 20 (2009): 393–98.

13. Independent Sector, “Giving and Volunteering in the United States—2001,” www.independentsector.org.

14. K. G. Carman, “Social Influences and the Private Provision of Public Goods: Evidence from Charitable Contributions in the Workplace,” Stanford Institute for Economic Policy Research Discussion Paper 02-13, January 2003.

15. J. K. Goeree and others, “The 1/d Law of Giving,” http://www.hss.caltech.edu/~lyariv/Papers/Westridge.pdf (accessed March 4, 2009).

16. S. Leider and others, “Directed Altruism and Enforced Reciprocity in Social Networks: How Much Is a Friend Worth?” (May 2007), NBER Working Paper No. W13135, http://ssrn.com/abstract=989946.