The comparison with aggressive behaviour and play led to the hypothesis that quasi-aggressive behaviour is a form of social exploration, a means for youngsters to learn about their social environment.
Two functional forms can be distinguished:
1. Reducing uncertainty, directed by male and female youngsters towards female targets;
2. Investigating authority, directed by male youngsters towards adult males.
Social learning in young chimpanzees does not occur only through observation, imitation and conditioning, but also through the exploratory activities of the youngsters themselves.
As youngsters grow older, gradual changes occur in the nature of the behaviour displayed and in the objectives the youngsters try to achieve.
Young chimpanzees in the Arnhem Zoo chimpanzee colony are frequently observed throwing sticks and stones at adult groupmembers, slapping or punching them. This behaviour becomes noticeable at the age of two and continues until adolescence at about the age of nine. Even occasional punishment does not discourage the youngsters from persisting in this type of annoying behaviour, also referred to as teasing, pestering, harassment, provocative behaviour, etc.