Scientific American:

Aiding others can even help you live longer. A study of older adults compared receiving social support and giving it as predictors of mortality over a period of five years. Whereas it would be intuitive to think receiving such support would be good for oneself, the results showed it was giving social support that predicted longevity: Those who provided instrumental support to friends, relatives and neighbors as well as those who provided emotional support to their spouses were more likely to be alive at the end of the study period compared with less pro-social participants. These results held true even when the researchers controlled for various demographic factors such as health, mental health, personality and marital status.

More than 10 studies have also demonstrated regular voluntary work predicts longevity. Helping behavior can even buffer against the negative effect that stress typically has on mortality: Among 846 participants around Detroit, stressful events predicted subsequent mortality among people who did not provide help to others in the past year but not among those who did.

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