Intraspecific aggression is activated by rivals, and by anti-social behaviour. The goal of the drive is to cause avoidance, submission, or worse of the rival. Biological significance is even distribution of a species over available land to reduce the possibility of food shortages and epidemics. As well as survival of a species and a pack by selecting the fittest animals for reproduction and as leaders. In species with a social hierarchy behaviours developed from the aggressive drive, which limit the negative results and guarantee the positive results of social aggression such as threatening, dominance, submission, and rituals of non-physical combat.
Aggression increases through maturation and practise.
It can also be increased or decreased through training and through external influences, for example pain can be aggression stimulating. Other factors which affect aggressive behaviour are location and hormone levels. A negative side effect of aggression in dog training is that it greatly reduces the dog's learning ability. Too often high quality dogs don't reach their potential because their owners want to see them aggressive right from the start, forgetting about the fact that the dog has to learn many intricate exercises before he can walk onto the competition field. So if possible teach the dog an exercise first, then make him perform it aggressively.