“A friend will always be there for you.” Yes, but why?

Tracing the evolutionary roots of friendship is proving to be more difficult than expected. What are the evolutionary benefits of friendship? Friendship doesn’t boost the survival of the family genes, since friends are outside the family. And although altruism and “giving back” have indirect evolutionary advantages, such reciprocity is not a strict requirement for being friends. What about loyalty? True, the loyalty that comes with friendship can help a friend survive. But how do such devoted relationships get started? It takes more than mere similarity and more than just being members of the same group.

Alliances among animals may hold a clue. A BBC piece summarizes animal studies suggesting that friendship might have evolved from relationships that provide social standing or protection. One study describes two groups of dolphins that, after having fought each other in the past, came to their mutual defense when a third group started attacking one of them. Such an alliance does seem like the kind of relationship that could develop into the “us against the world” ideal of friendship that humans cherish.

I like such explorations that, although they are only hypotheses and observations along the way towards an explanation, highlight an aspect of our experience that we may not even be conscious of—especially when it is as gussied up by cliches and marketing hype as friendship is. Thinking over my handful of long-time friendships, I think a sense of alliance—not of the defensive sort but a sense of solidarity—has indeed played a role in them, either early on or after a while.

Friendship-as-alliance certainly makes sense when you consider how quickly we humans can leap to suspicions about others around us, from siblings to other nations. So it’s not surprising that we’ve also inherited habits of stocking our lives with allies of many kinds, friends among them. Our lives, like all lives, are partly about protection—protection from injury, from death, from chaos. The pleasures of friendship and the energy that we invest in it are signals of a sort from evolution that friendship is a valuable protection.