Chimpanzee Police

Research published this week gives get another clue that humans are not the only animal with moral behavior. A team of scientists, led by anthropologist Claudia Rudolf von Rorh out of the University of Zurich, have been studying what they call "policing" behavior in several groups of captive chimpanzees. (Here is their published study.)

As we know from our experience as human animals, living in large social groups inevitably involves conflict, and effective management of these conflicts is essential to the stability of the group. Scientists studying animal behavior have found that animals have a wide range of strategies for dealing with internal conflict, including dominance, reconciliation, coalition building, and punishment. Another, somewhat rarer, form of conflict management is policing behavior, in which an impartial bystander intervenes in a conflict in order to maintain the peace.

Von Rorh's group explored how different factors within a group of chimpanzees might affect policing behavior. In the most striking example, they observed a group just after two potentially destabilizing events: a new female had recently been introduced and a rank reversal had occurred between two high-ranking males. As expected, policing behavior spiked within this group.

What's interesting about policing behavior, from an evolutionary perspective, is that the interventions are impartial and never involve aggression toward one of the contestants. The behavior seems to have no direct fitness benefits for the policing individual him or herself. In fact, the policing has potential costs to the individual, including the risk of getting injured. These policing animals are acting as arbitrators, trying to resolve conflicts within the group and increase group stability. As von Rorh and collegues suggest in their paper, policing is a form of prosocial behavior based upon "community concern" and may be "a precursor of human morality."

Policing behavior has also been reported in bonobos, mountain gorillas, captive orangutans, and macaques. Oh, and of course humans.

Marc Bekoff and I argued in our book Wild Justice: The Moral Lives of Animals

that moral behaviors like empathy, fairness, and helpfulness are present in many species animals, and that morality is an important ingredient in the evolution of sociality. This week's research adds yet another piece of evidence to the growing body of research into animal morality, and reminds us, again, that animal communities are vibrant, complex.