Two personality traits for men and women that contribute to a longer lifespan

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Men with conscientious personality traits and those who are open to experience live longer, a new study finds. For women, those who are more agreeable and emotionally stable enjoy a longer life.

The kicker is that it's your friends — not you — who are better at judging these personality traits from the outside.

The results, published in the journal , come from one of the longest studies in history, spanning 75 years (Jackson et al., 2015).

Dr Joshua Jackson, the study's first author, said:

"You expect your friends to be inclined to see you in a positive manner, but they also are keen observers of the personality traits that could send you to an early grave."

The researchers used data from research that began in the 1930s, following a group of couples then in their mid-20s.

Almost all were about to be married and tests of their personality traits were conducted on the engaged couples and their friends also reported on the couple's personalities.

Dr Jackson said:

"Our study shows that people are able to observe and rate a friend's personality accurately enough to predict early mortality decades down the road.

It suggests that people are able to see important characteristics related to health even when their friends were, for the most part, healthy and many years from death."

But why is it that friends are better at judging how long we'll live from personality traits?

Dr Jackson says:

"There are two potential reasons for the superiority of peer ratings over self ratings.

First, friends may see something that you miss; they may have some insight that you do not.

Second, because people have multiple friends, we are able to average the idiosyncrasies of any one friend to obtain a more reliable assessment of personality.

With self reports, people may be biased or miss certain aspects of themselves and we are not able to counteract that because there is only one you, only one self-report."

Dr Jackson pointed out that the personality traits which predict long life may be different if the study were started again today. That's because the personality traits associated with a longer life in the 1930s may reflect out-dated gender roles.

In the 1930s women's roles in society — often as easy-going, supportive wives — were much more confined. Nevertheless, the study is a fascinating demonstration of the link between personality and longevity.

Dr Jackson said:

"This is one of the longest studies in psychology.

It shows how important personality is in influencing significant life outcomes like health and demonstrates that information from friends and other observers can play a critical role in understanding a person's health issues.

For example, it suggests that family members and even physician ratings could be used to personalize medical treatments or identify who is at risk for certain health ailments."