Biologists have long observed that groups of animals can coordinate their actions so tightly that each animal does what is best for the group rather than what is best for itself -- even when group members are unrelated. But explaining how such genetically selfless behavior could have evolved has long been just beyond the reach of scientists seeking to employ standard evolutionary theory.

In new theoretical research, Erol Akçay (Princeton) and SFI Omidyar Fellow Jeremy Van Cleve demonstrate the crucial role flexible behaviors might play in the evolution of high levels of cooperation. Such behaviors can include simple negotiations involved in food sharing and the social norms that prevent an individual’s cowardly retreat when a group must defend itself against hostile outsiders. Their work appears in the February issue of The American Naturalist.

By incorporating flexible behaviors into standard biological theory that describes how cooperation evolves based solely on genetic kinship, the researchers suggest that high levels of cooperation can evolve even in groups not composed of close relatives.

Specifically, they find that cooperation can evolve to group-optimal levels when individuals match each other’s actions closely, regardless of the relatedness between individuals.

But kinship does matter. They also find that whether a psychology that enables such behavior-matching evolves or not depends on the relatedness of between-group members.

“Relatedness and behavioral responses can interact synergistically and promote much higher levels of cooperation together than each of them can sustain by themselves,” explains Akçay.

Jeremy says an exciting characteristic of their approach is that it can be used to study the evolution of psychological mechanisms that generate specific behaviors. They demonstrate this by studying how prosocial preferences -- i.e., intrinsic motivations to help others -- can evolve to maximize group benefit.

Although popular in economic theories, prosocial preferences have received little attention by biologists. How easily prosocial preferences evolve depends on the kind of activity in which animals might cooperate.

“When animals hunt cooperatively, they can capture much larger prey than when alone, which is good for all, and this can make high levels of cooperation easier to evolve,” says Jeremy.

For activities where adding additional cooperators makes less of a difference, such as emitting alarms calls when predators are nearby, high levels of cooperation are harder to evolve.

Read the study in The American Naturalist (February 2012)

Watch Jeremy Van Cleve describe his research interests in an SFI video (3 minutes)

Read the article in the SFI Update (March-April 2012)

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