Friends are fun to hang out with? So that's what we keep them around for! And – bonus – not only do friends make us happy, but they're also good for our health, too, since they make our lives less miserable and pathetic.
Lots of research has been conducted to figure out whether friendship is really worth the cost of having friends. Turns out it is. Perhaps the starkest and most macabre study discovered that over a 10-year period, people with lots of friends were 22 percent less likely to die [source: New York Times]. So that's a plus. Friends have also been shown to make compadres more optimistic (enemies aren't often heralded for boosting self-esteem) and they can help lower stress levels, too.
Friendship can be a double-edged sword, however, because friends can also be your downfall. Another study found that if one friend gains weight, others in the close social circle have a 60 percent chance of following suit. After all, it's not like somebody with friends is going to go at the Cheesecake Factory all alone, right?
So we guess the takeaway is, um, to paraphrase "Indiana Jones and the Last Crusade": Choose wisely, for true friends will give you life and false ones will take it from you.