For example, built-up frustration due to blocked goals or perceived disrespect. In humans, aggression can be caused by various triggers. It may occur either reactively or without provocation. Two warthogs preparing to fightĪggression is hostile and antagonistic behavior, often with the intent to cause harm, although it can be channeled into creative and practical outlets for some. Many mammals, such as the dog, bare their teeth as a sign of aggression a form of aposematism. For other uses, see Aggressive (disambiguation), Aggression (disambiguation), and Aggressive Behavior (journal). 'Aggressive' and 'Aggressive behavior' redirect here.