If you think longevity solely comes down to genes and diet, think again. Our social life -- the family ties and the bonds you have with friends and community -- might also play a vital role. Adolfo Melis, who lives on the island of Sardinia, in Italy, is testament to this way of thinking.

He might be 94, but he says he feels like 50. Melis is still active -- he's one impressive pool player -- he doesn't need glasses to read the newspaper, and he gets up early enough to serve coffee from 6 a.m. onwards at his coffee shop. Importantly, "'all my customers are my friends, and everyone knows each other," Melis said.