Bullying is not easy to define, namely because there is no one way to bully. It comes in many forms, from physical playground scuffles to verbal attacks. Even governments have a hard time defining it, often referred to as a repeated behaviour with the intent to hurt someone either physically or emotionally. By this definitions, there are many ape and monkey bullies, too. In fact, any hierarchical society is likely to have bullies in its midst.

An unfortunate monkey at the bottom of the hierarchy is repeatedly attacked and picked upon by those higher up in the group - they are sometimes beaten up every day. Bullying amongst rhesus macaques, for example, seems to release tensions among the higher-ups. Bullying seems to reinforce their bonds, a ...