Following groups of children through life is one of the more interesting things that researchers do -- usually with the intention of improving public health, welfare and education policies.

An American study that began in 1921 with the aim of identifying the intellectual achievers of the future has now, nine decades later, yielded another kind of information: which childhood characteristics and experiences are likely to extend a person’s life or shorten it. These results have just been published in a book, The Longevity Project, by Howard S Friedman and Leslie R. Martin.

Lauro Landro reports in The Wall Street Journal:

There are no magic potions on offer here, but many of the findings are provocative. The best childhood predictor of longevity, it turns out, is a quality best defined as conscientiousness: "the often complex pattern of persistence, prudence, hard work, close involvement with friends and communities" that produces a well-organized person who is "somewhat obsessive and not at all carefree."

The original researcher, Stanford University psychologist Lewis Terman, asked teachers to select their brightest students (most were around the age of 10) but having a high IQ did not seem to play a direct role in longevity:

Neither did going on to an advanced degree. The authors suggest that persistence and the ability to navigate life's challenges were better predictors of longevity.

Fortunately, Terman’s questionnaires were very detailed and picked up all sorts of things about the students’ lives and later development. So, eight decades later it was also possible to see what things tend to shorten a person’s life, and there was one particularly strong family factor:

Some of the findings in "The Longevity Project" are surprising, others are troubling. Cheerful children, alas, turned out to be shorter-lived than their more sober classmates. The early death of a parent had no measurable effect on children's life spans or mortality risk, but the long-term health effects of broken families were often devastating. Parental divorce during childhood emerged as the single strongest predictor of early death in adulthood. The grown children of divorced parents died almost five years earlier, on average, than children from intact families. The causes of death ranged from accidents and violence to cancer, heart attack and stroke. Parental break-ups remain, the authors say, among the most traumatic and harmful events for children.

The world has changed a lot since those 1500 children grew up, matured and died, and they were a very select group to start with -- all white and middle-class, for starters -- but even given the limitations, the links Friedman and Martin have discovered are worth considering:

…The respondents to the study who fared best in the longevity sweepstakes tended to have a fairly high level of physical activity, a habit of giving back to the community, a thriving and long-running career, and a healthy marriage and family life. They summoned resilience against reverses and challenges— including divorce, loss of a spouse, career upsets and war trauma. By contrast, those with the darkest dispositions—catastrophizers, who viewed every stumble as a calamity—were most likely to die sooner…

The bad news about cheerful kids is a bit hard to swallow, but it seemed to be linked with recklessness later in life. Perhaps it depends on what you mean by “cheerful”. Friedman and Martin suggest that this finding underlines the importance of cultivating forethought and purposefulness in children.

One can be conscientious and still be cheerful, surely.