For example, if a dog shows extreme aggression every time it sees another dog of the same sex, it is showing abnormal behaviour. However, this behaviour is not likely to be pathological unless it is due to hormonal or organic changes in the brain. The word aggression often carries negative connotations. The word is usually associated with struggle and violence. Yet according to some scientists, aggression is what makes personal relationships possible-it's the basis for friendship and love.
Conspecifics compete over vital resources like food, territory and sexual partners.
It is of great importance for animals to have certain mechanisms with which they can control others. Aggression is the drive behind the initial desire of one individual to kill another, or preferably chase it away. Encounters between individuals of many species occur in this way. For example, a tiger cub's worst enemy, besides a human, is an adult male tiger, which may even be their own father. However, other animals have realised that they need help from conspecifics to survive.