Anthropologists now reveal that chimpanzees mediate conflicts between other group members, not for their own direct benefit, but rather to preserve the peace within the group. Their impartial intervention in a conflict — so-called “policing” — can be regarded as an early evolutionary form of moral behavior.
…primatologists from the University of Zurich can now confirm that chimpanzees intervene impartially in a conflict to guarantee the stability of their group. They therefore exhibit prosocial behavior based on an interest in community concern.
…The willingness of the arbitrators to intervene impartially is greatest if several quarrelers are involved in a dispute as such conflicts particularly jeopardize group peace.
…It is primarily high-ranking males or females or animals that are highly respected in the group that intervene in a conflict. Otherwise, the arbitrators are unable to end the conflict successfully. As with humans, there are also authorities among chimpanzees.
The article is here and for the pointer I thank Eduardo Pegurier.