In 1976, a Greek veteran who had immigrated to the United States was diagnosed with lung cancer and given nine months to live.  Facing death, he decided to return to his native Greek island, Ikaria.  There, he prepared to die.  But, after a few months, he starting feeling better.  In fact, today, three-and-a-half decades later, he’s still alive.

This story, remarkable in its own right, isn’t the only one of its kind.  The island of Ikaria is being studied by several demographers who are investigating the places in the world where people live longer.  Dan Buettner, who travels the globe in an effort to better understand longevity, recently explained in the New York Times that he, Dr. Gianni Pes of the University of Sassari in Italy, and Dr. Michel Poulain, a Belgian demographer, work together to study these “blue zones.”

Starting in 2002, we identified three other populations around the world where people live measurably longer lives than everyone else. The world’s longest lived women are found on the island of Okinawa. On Costa Rica’s Nicoya Peninsula, we discovered a population of 100,000 mestizos with a lower than normal rate of middleage mortality. And in Loma Linda, Calif., we identified a population of Seventhday Adventists in which most of the adherents’ life expectancy exceeded the American average by about a decade.

These researchers had their work cut out for them.  Tracking down the ages of people, especially those who didn’t have birth certificates, proved difficult to say the least.  “One year they were 80; a few months later they were 82. Pretty soon they claimed to be 100.”  It’s easy to lose track.

Once they were assured that these blue zones were real, they turned to studying their ways of life.  Buettner spent time learning more about the Greek Island of Ikaria, which you can read here.  As he details, their diets are important, consisting of much olive oil and wild greens, low amounts of dairy (except goat’s milk) and meat products, and moderate amounts of alcohol.   But, communal lifestyle also seems to matter.  Ikaria is a communal place—an “us place,” not a “me place.”  As a resident told Buettner,

 “Do you know there’s no word in Greek for privacy?…When everyone knows everyone else’s business, you get a feeling of connection and security…If your kids misbehave, your neighbor has no problem disciplining them. There is less crime, not because of good policing, but because of the risk of shaming the family. You asked me about food, and yes, we do eat better here than in America. But it’s more about how we eat.Even if it’s your lunch break from work, you relax and enjoy your meal. You enjoy the company of whoever you are with. Food here is always enjoyed in combination with conversation.”

In fact, social structure might be one of the most important reasons behind their (and other Blue Zones’) secrets to longevity.  Beyond community, the centenarians in these locations often live engaging lives together, which gives them meaning.  As the Nicoyans in Costa Rica like to put it, they have a “plan de vida,” or a lifelong sense of purpose.