Friendships are built on alliances, research shows

New research from the University of Pennsylvania is challenging some longtime assumptions about why human beings seek and keep their friends, and it reveals a somewhat darker side to the very nature of friendship itself.

Peter DeScioli, who recently earned his Ph.D. at Penn and is currently a fellow at Brandeis University, says his recent research, completed in conjunction with Robert Kurzban, Penn associate professor of psychology, and researchers at two other universities, offers new evidence supporting the so-called "alliance hypothesis" of friendship, which states that individuals' feelings about their are based mostly on how those friends feel about them.

This alliance hypothesis, which also states that are valued because of their usefulness during times of conflict, contrasts with the more conventional "reciprocity" theory of friendship, which holds that humans make friends mostly in order to reap the reciprocal benefits of those friendships.

The findings were published on Feb. 3 in the journal .

"Traditionally, one of the main theories about friendship is that friendships are essentially trade relationships," DeScioli said "You do things for your friends, and they do things for you. The problem with this theory is, if it were true, then we should be good accountants and keep track of what we do for friends and what they do for us. There is evidence, however, that we don't do that."

To figure out, then, if human beings make friends for reasons other than "trade," the researchers hit the Internet. Specifically, they went to MySpace, the social networking site that, unlike other sites, allows people to "rank" their friends.

Leveraging a massive database built from the site — about 11 million data points in all — the researchers set to out to determine how much of a factor "friend rank" played in an the perceived strength of friendships.

As it turned out, that rank was of massive importance.

Kurzban explained that, if Joe Smith was ranked No. 1 by one of his friends, he was significantly more likely to also rank that friend in the top spot. For example, the results showed that, comparing first- and second-ranked friends, 69 percent of people chose as their best friend the individual who ranked them better. And while other factors also played a role in how friends valued their friends — geography, for instance — none of them played as great a role as rank.

"In some ways, this is obvious, right?" Kurzban said. But “we argue in the paper that, while obvious, no theory predicts this finding, and, further, very little data exist to substantiate the intuition.”

The bottom line? People greatly value those friends who greatly value them above others. They are less impressed with those who rank them lower. We are, it seems, very jealous beings.

"If you think about friendships in terms of alliances, in the context of game theory and international relations, one of the main things you'll find about allies is that they are fundamentally jealous of each other,” DeScioli said. “If Saudi Arabia is allies with the , it's not just concerned about its relationship with the United States. It's also concerned about the relationship that the United States has with other nations such as Iran. In reciprocal or exchange relationships, you don't care about how, for example, Wal-Mart feels about other people. You just care about what you're getting out of the relationship."

This dynamic is so important, the researchers suggest, because humans apparently see their friends as protection — not to mention valuable assets that can be leveraged when conflict arises.

"You have to build friendships in advance," DeScioli said. "You have to build a network of people who care about you, before any arguments or scuffles come up. That's the theory, that humans create these networks so we can potentially use them in the future. When you have this network of allies, you don't have to worry about direct reciprocity."

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Be your best friend if you'll be mine: Alliance Hypothesis for Human Friendship

Citation: Friendships are built on alliances, research shows (2011, February 7) retrieved 17 September 2019 from
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Feb 08, 2011
The paper behind a paywall is
Peter DeScioli, Robert Kurzban, Elizabeth N. Koch, David Liben-Nowell

Best Friends: Alliances, Friend Ranking, and the MySpace Social Network
Perspectives on Psychological Science
January 2011 6: 6-8,

Feb 08, 2011
I wonder how would this hypothesis explain the formation of friendship between two people who initially hate each other.
I also wonder if people really know how high their friends "rank" them in real life outside of myspace.

Feb 08, 2011
@ orsr
I think they are not necessarily discounting the notion that friendships -can- arise in other situations even including the reciprocal relationship. However, the underlying commonality seems to be the availability of a friend as "leverage" against confrontations or as support in general.

To reply specifically to your wondering how initial hatred/enemies can become friends, it is the very same principle. Not necessarily based on jealousy as a fundamental, but in this case a respect that each other would be much better off having the other in a supportive role than a combative one. Respecting strengths (and in that way being jealous of them) may lead to desiring that strength to be with you rather than against you.

Feb 08, 2011
@ orsr (continued)

People are able to gain subtle social cues to let them know how their friends rank them in real life. First of all, if you never hear a person tell you that you are their best friend, chances are you are not ranked in the top spot or even any top spot. You may conclude by how often that person initiates contact with you or by how often introductions made by your friend result in a response of "oh so this is [your name], I've heard about you" and similar instances. How affectionate a friend is to you (whether they simply shake hands, give "daps," hug/bro hug, kiss on the cheek in the case of females or other cultures) is another good indicator of their perceived ranking of you. Also, how often you choose to initiate contact with or even think about that person and what they are doing.

There are plenty of indicators, including asking mutual friends or relatives. Now, whether most people are aware of their 'ranking' is debateable.

Feb 21, 2011
Am i the only one to think it weird for those researchers to consider that our so-called "friends" on social networks *are* friends?

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