Scientists might be able to predict how long you'll live based on … what your friends think of you.
So says a study published in Psychological Science, in which researchers found that subjects whose friends viewed them as more conscientious and open tended to have longer lives. The men seen as the most conscientious had a 30 percent lower mortality risk than average; the women considered the most emotionally stable and agreeable had a 15 percent lower risk.
How come you can't just rank yourself to predict when you'll die? As Pacific Standard explains, "your friends’ beliefs about your traits are, when averaged, more reliable than your own." (Researchers found a weaker connection between mortality and how men assessed themselves, while women's self-assessments were actually inaccurate at predicting longevity, Psych Central reports.)
Not only might you be biased, the way you see yourself could change based on external variables.
Other studies that have linked personality traits to health and mortality are more limited than this one, because they have relied on subjects rating their own traits. So, in this case, researchers used data from the Kelly Longitudinal Study, in which 300 young married couples were assessed starting in the mid-1930s. Part of the study involved three to eight friends of each couple answering questions about their personalities. Researchers then compared those results to death records (or confirmation, in some cases, that the subjects had not yet died) for all but seven of the subjects. Of course, it should be noted that the friends' assessments were taken decades ago — when, the Huffington Post notes, people may have had different ideas about what it means to be an "agreeable" and "emotionally stable" woman.
(Another recent study found that optimism is good for your heart.)