Aggressive Behaviour

Aggressive Behaviour
any action of an animal that serves to injure an opponent or prey animal or to cause an opponent to retreat. The term is used in manydifferent ways, however, and no single definition can possibly cover all of its meanings. When considering human aggression, for example, some psychiatrists consider any act that has destructive consequences (including suicide) to be aggressive. (For a discussion of aggressivebehaviour in man, see emotion.) Thus, the role of aggression in behaviour has been—and continues to be—debated by psychologists and ethologists, as is the meaning of the term itself. Frequently, aggressive behaviour encompasses both attack and defense. Other investigators exclude food-gathering behaviour, though it may involve attack on another animal.

In order to avoid these ambiguities of definition, a distinction must be made between causation, function, and description of observed behaviour. It is frequently assumed that a single motivational system (aggression) causes all recognizably aggressive behaviour in higher animals. This assumption is certainly invalid for invertebrates and for most higher vertebrates, in which a variety of motivational bases appear to exist. A motivational definition of aggression is thus difficult. The only possible rigorous approach is to list patterns of behaviour, usually held on both functional and causative grounds to be aggressive. Because aggressive behaviour has been most studied in mammals, mammalian behaviour will be examined here first as a basis for comparison with other animals.