Cooperation? It's Human Nature

Society has thrived because of people's willingness to punish those who misbehave

THURSDAY, March 13, 2003 (HealthDayNews) -- When social scientists look at human society, they're struck by a basic difference between us and other mammals: humans are the only species that depends on cooperation among strangers.

In primates, our closest genetic relatives, cooperation occurs only among closely related groups -- mothers, fathers, children and other relatives share food, grooming and responsibility for protecting the group.

But in modern human societies, daily life involves cooperation among people who hardly know each other. This cooperation is evident in large ways (in our ability to form corporations and governments) and small (a waiter counts on getting tipped; you count on your neighbors to not steal your newspaper in the morning).

Now, new research offers evidence to explain how humans are able to accomplish this.

Many social scientists believe the key to maintaining order in such large, non-related groups is "altruistic punishment," that is, people stepping forward to keep members of the group in line even when the confrontation costs them, says study author Robert Boyd, an anthropology professor at the University of California, Los Angeles.

The problem with this concept, however, is that social scientists also believe people act in their own self-interest.

"The longstanding assumption is that people, like other animals, are mainly selfish," Boyd says. "Natural selection should not favor behavior that benefits others if it costs the individual doing the behavior."

Boyd's new research at least partially solves the dilemma.

Using a mathematical simulation of a simple human society, Boyd and his colleagues found that when society is functioning well, just the threat of punishment is enough to make the need for actual punishment rare.

Therefore, there isn't actually much cost to the altruistic punishers because they rarely have to take action.

"It's a sleight of hand," says John Hibbing, a professor of political science at the University of Nebraska in Lincoln. "The person who is willing to punish at cost to himself is not going to have to suffer many costs because there won't be many instances in which people behave badly."

The study appears in this week's issue of the Proceedings of the National Academy of Sciences.

The concept of altruistic punishment is widely accepted by social scientists, Hibbing explains.

One way of better understanding the concept is through a test called the "ultimatum experiment."

In it, participants are given some amount of money, say $20. Person A is told they can give Person B some portion of the money, but Person B has the right to refuse their offer. If Person B refuses the offer, neither gets to keep any money.

Experiments show Person A most often gives Person B about half of the money. But when Person A offers a paltry sum, Person B usually rejects the money, even though by punishing Person A for dividing the money unfairly Person B also loses.

Still other laboratory experiments have found that people are more likely to punish members of a group for behaviors that harm the group than to spontaneously do nice things for the group themselves.

To further test the theory of altruistic punishment, Boyd and his colleagues created a mathematical simulation of a simple society, in which humans were one of three personality types: "cooperators," who keep the wheels of the society spinning by doing what they're supposed to or expected to do; "defectors," who break the rules, and "altruistic punishers," who confront those who misbehave.

Previous research has shown societies that are dominated by "altruistic punishers" do the best over time.

Boyd's research found the mere threat of punishment from the altruistic punishers is enough to prevent most of the non-cooperation.

There is also some evidence that people occasionally do things that are not in their own self-interest to benefit the group, Boyd says.

That is the most controversial finding of the paper, Hibbing says. Many social scientists firmly believe there is no such thing as true altruism in human society, or the idea that people will act in a way that benefits the group at a cost to themselves.

"Most scholars who work in this area are very resistant to this idea, but it's starting to be talked about with increasing seriousness," he says.

More information

Read more about the role of altruism and self-interest in human societies at MIT. And here's more on human behavior and evolution.

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