Scientists love to solve the unanswerable questions in life, wrapping up tidy answers with equations or charts or definitions, leaving no gray area. Unfortunately for some researchers, not everything is so black and white. Can we really define love? Is success simply the sum of the right variables put into the right equation? Does happiness have a graph or flow-chart that guarantees statistically significant results?

The secret to a happy life has eluded mankind for generations. Ancient philosophers, progressive thinkers, and contemporary educators have all offered theories and opinions on what makes us happy. But no one has collected more objective evidence on the subject than researchers from the Harvard Medical School. The Harvard Study of Adult Development began in 1937, examining more than 200 healthy, well-adjusted Harvard sophomores. The study has become the preeminent example of a longitudinal study, following its subjects for more than 70 years. The group of men is not at all representative of the population as a whole, consisting entirely of well-educated, socioeconomically-favored males, but the homogenous group of subjects has still uncovered some surprises in the quest for happiness.

Over the years of the study, researchers have collected extensive information on the men’s physical, mental, and emotional health, and compared this to their accomplishments in their occupations, marriages, and hobbies, as well as their self-perceived level of satisfaction with life. Researchers have found that cholesterol levels in middle age had no correlation to overall health in old age. They concluded that regular exercise in college was positively correlated with mental health later in life. They discovered that religious involvement, in contrast to many previously reported studies, was not associated with physical, mental, or social well-being.

Successful aging and happiness later in life, the researchers have concluded, is predicted by many difference variables — some of which can be controlled, and some of which cannot: parental social class, family cohesion, major depression, ancestral longevity, childhood temperament, physical health at age 50, alcohol abuse, smoking, marital stability, exercise, body mass index, coping mechanisms, and education. Ultimately, there is no one secret to a happy, successful life. Men who seemed to have every advantage in life failed to succeed in careers and family life, and many have died prematurely or unexpectedly. Men, on the other hand, who seemed doomed for failure due to their circumstances rose to the challenge and eventually led exceptional lives.

It turns out that success and happiness might not be determined by what you know, but by who you know. The closest thing that researchers have been able to identify as a single secret to happiness is successful relationships. High levels of intelligence, social aptitude, physical strength, or mental health mean very little in the pursuit of happiness. Positive relationships — with parents, siblings, spouses, children, friends, neighbors, and colleagues — as early as childhood are the most important predictors of happiness and success as we age. Largely, loving relationships and an appreciation for beauty positively predict life satisfaction.

Of course, happiness and life satisfaction are individually defined, depending on culture, society, and personality. Self-expression and individualism play an important role in happiness in many cultures, while simple survival constitutes a successful life in others. But, however we define happiness, positive emotions are linked to resilience and a satisfaction for life. As much as scientists are called to delineate objective measures of subjective experiences, maybe we should heed Albert Camus’s warning:

You will never be happy if you continue to search for what happiness consists of.

References

Cohn, M., Fredrickson, B., Brown, S., Mikels, J., & Conway, A. (2009). Happiness unpacked: Positive emotions increase life satisfaction by building resilience. Emotion, 9 (3), 361-368 DOI: 10.1037/a0015952

ISAACOWITZ, D., VAILLANT, G., & SELIGMAN, M. (2003). STRENGTHS AND SATISFACTION ACROSS THE ADULT LIFESPAN The International Journal of Aging and Human Development, 57 (2), 181-201 DOI: 10.2190/61EJ-LDYR-Q55N-UT6E

Kuppens P, Realo A, Diener E. The role of positive and negative emotions in life satisfaction judgment across nations. J Pers Soc Psychol. Jul 2008;95(1):66-75. doi:10.1037/0022-3514.95.1.66

VAILLANT, G., TEMPLETON, J., ARDELT, M., & MEYER, S. (2008). The natural history of male mental health: Health and religious involvement Social Science & Medicine, 66 (2), 221-231 DOI: 10.1016/j.socscimed.2007.09.011

Vaillant, G., DiRago, A., & Mukamal, K. (2006). Natural History of Male Psychological Health, XV: Retirement Satisfaction American Journal of Psychiatry, 163 (4), 682-688 DOI: 10.1176/appi.ajp.163.4.682

Vaillant, G. (2001). Successful Aging American Journal of Psychiatry, 158 (987), 839-847 DOI: 10.1176/appi.ajp.158.987.839

Waldinger RJ, Vaillant GE, Orav EJ. Childhood sibling relationships as a predictor of major depression in adulthood: a 30-year prospective study. Am J Psychiatry. Jun 2007;164(6):949-954. doi:10.1176/appi.ajp.164.6.949

Shenk JW. What Makes Us Happy? The Atlantic; 2009.