What's the exact recipe for happiness? What's the alchemy to assure success? What are the clear signs that in your twenties you will be off the tracks in your forties? You could delve deep into the Big Think archives for these answers, or you could take note of a Harvard endeavor that began in 1942.

Longitudinal case studies can be breathtakingly boring and uninsightful, but, given the right documentary lens, they can authoritatively highlight life's great lessons.

There's the masterful BBC series Seven Up! which interviews 14 Brits every seven years across five decades. Throughout the conversations, the importance of social class in British society gets thorough treatment, revealing a few surprises and confirming prior assumptions.

In 1937 Harvard psychiatrist George Vaillant started a little Seven Up of his own, the Grant Study, which the Atlantic brings to light this month.

With the aim of reducing “the disharmony of the world at large,” Vaillant traced, and continues to trace, the life histories of 269 Harvard students investigating in large part how well his subjects were able to adapt to life's troubles and the quotient of happiness they afforded themselves by their adaptations.

The crux of one's success or failure to adapt, Vaillant found, was in an individual's defense mechanisms. As the magazine writes:

"Vaillant explains defenses as the mental equivalent of a basic biological process. When we cut ourselves, for example, our blood clots—a swift and involuntary response that maintains homeostasis. Similarly, when we encounter a challenge large or small—a mother’s death or a broken shoelace—our defenses float us through the emotional swamp. And just as clotting can save us from bleeding to death—or plug a coronary artery and lead to a heart attack—defenses can spell our redemption or ruin."

In introducing the Grant Study, Vaillant elaborates on "the miserable process of getting from 25 to 35." Take note, the whole life thing does get better over time, he says.

Before you tackle the Grant Study, listen to one of Big Think's neuroscientists, John Cacioppo, who gives us a working definition of happiness.