Your friends know how long you will live: a 75-year study of peer-rated personality traits.

Although self-rated personality traits predict mortality risk, no study has examined whether one's friends can perceive personality characteristics that predict one's mortality risk. Moreover, it is unclear whether observers' reports (compared with self-reports) provide better or unique information concerning the personal characteristics that result in longer and healthier lives. To test whether friends' reports of personality predict mortality risk, we used data from a 75-year longitudinal study (the Kelly/Connolly Longitudinal Study on Personality and Aging). In that study, 600 participants were observed beginning in 1935 through 1938, when they were in their mid-20s, and continuing through 2013. Male participants seen by their friends as more conscientious and open lived longer, whereas friend-rated emotional stability and agreeableness were protective for women. Friends' ratings were better predictors of longevity than were self-reports of personality, in part because friends' ratings could be aggregated to provide a more reliable assessment. Our findings demonstrate the utility of observers' reports in the study of health and provide insights concerning the pathways by which personality traits influence health.