The willingness of people to punish others who lie, cheat, steal or violate other social norms even when they weren't harmed and don't stand to benefit personally, is a distinctly human behavior. There is scant evidence that other animals, even other primates, behave in this "I punish you because you harmed him" fashion. Although this behavior called third-party punishment has long been institutionalized in human legal systems and economists have identified it as one of the key factors that can explain the exceptional degree of cooperation that exists in human society, it is a new subject for neuroscience.
In a paper published online on April 15 by the journal Nature Neuroscience, a pair of neuroscientists from Vanderbilt and Harvard universities has proposed the first neurobiological model for third-party punishment. It outlines a collection of potential cognitive and brain processes that evolutionary pressures could have re-purposed to make this behavior possible.
"The concepts of survival of the fittest or the selfish gene that the public generally associates with evolution are incomplete," said Ren Marois, associate professor of psychology at Vanderbilt, who co-authored the paper with Joshua Buckholtz, assistant professor of psychology at Harvard. "Prosociality voluntary behavior intended to benefit other people even when they are not kin does not necessarily confer genetic benefits directly on specific individuals but it creates a stable society that improves the overall survival of the group's offspring."
One of the underlying mental abilities that allows humans to establish large-scale cooperation between genetically unrelated individuals is the capability to create, transmit and enforce social norms, widely shared sentiments about what constitutes appropriate behavior. These norms take a variety of forms, ranging from culturally specific standards of behavior (such as "thou shall greet an acquaintance of the opposite s
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