People stop their cars simply because a little light turns from green to red. They crowd onto buses, trains and planes with complete strangers, yet fights seldom break out. Large, strong men routinely walk right past smaller, weaker ones without demanding their valuables. People pay their taxes and donate to food banks and other charities.
Most of us give little thought to these everyday examples of cooperation. But to biologists, they’re remarkable — most animals don’t behave that way.
“Even the least cooperative human groups are more cooperative than our closest cousins, chimpanzees and bonobos,” says Michael Muthukrishna, a behavioral scientist at the London School of Economics. Chimps don’t tolerate strangers, Muthukrishna says, and even young children are a lot more generous than a chimp.
Human cooperation takes some explaining — after all, people who act cooperatively should be vulnerable to exploitation by others. Yet in societies around the world, people cooperate to their mutual benefit. Scientists are making headway in understanding the conditions that foster cooperation, research that seems essential as an interconnected world grapples with climate change, partisan politics and more — problems that can be addressed only through large-scale cooperation.
Behavioral scientists’ formal definition of cooperation involves paying a personal cost (for example, contributing to charity) to gain a collective benefit (a social safety net). But freeloaders enjoy the same benefit without paying the cost, so all else being equal, freeloading should be an individual’s best choice — and, therefore, we should all be freeloaders eventually.
