You saw it on 'Survivor': Alliances matter
While they didn't study the hit television show, researchers at the University of Pennsylvania conducted experiments on the motives behind human friendship. The prevailing theory is that humans build friendships in order to exchange goods and services, Penn psychologist Peter DeScioli, a co-author of the study, said in a news release. But that theory doesn't explain studies that show people usually don't keep tabs on the benefits they get from a friendship and will often help friends who are unable to repay them.
The new theory, called the Alliance Hypothesis for Human Friendship, argues that friendships form because of cognitive mechanisms aimed at creating alliances -- or ready-made support groups of people. Under this theory, how you rank your best friends is closely related to how they rank you. And friends tend to be valued according to who is the most helpful in settling conflicts and based on how many strong commitments they have to others.
"Friendships are about alliances," said psychologist Robert Kurzban, the other co-author of the study. "We live in a world where conflict can arise and allies must be in position beforehand. This new hypothesis takes into account how we value those alliances. In a way, one of the main predictors of friendships is the value of alliances. The value of an ally, or friend, drops with every additional alliance they must make, so the best alliance is one in which your ally ranks you above everyone else as well."
The researchers came to this conclusion by performing a series of question-and-answer studies in which participants ranked their closest friends in a number of ways. Friendship rankings were most strongly correlated with individuals' own perceived rank among their partners' other friends.
"In this hypothesis," Kurzban said, "it's not what you can do for me, it's how much you like me."
The study is published online in the journal PLoS One.
-- Shari Roan
Photo credit: Carolyn Cole / Los Angeles Times