The difference between abnormal and pathological behaviour is that the latter involves greater qualitative differences, while abnormal behaviour is an exaggeration of the norm. 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.

NORMAL BEHAVIOUR, PATHOLOGICAL BEHAVIOUR.
 
 
 

Aggression

Aggression is a drive-purposeful energy-which is aroused by meeting with a conspecific. 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. This is not a product of an individual's consciousness, but occurs at a species level-the fittest under specific circumstances is the survivor. For example, it is difficult for a lone wolf to get food for itself, but if there are two of them they significantly increase the chance of acquiring food, if there are three they can begin hunting systematically. In some species, selection favours those individuals who are best at inhibiting their aggression and co-operate instead. This does not mean aggression disappears, rather it assumes other forms through ritualised behaviour: greeting ceremonies, pacifying behaviour and rank ordering. Instead of killing each other, the animals engage in ritualised behaviour where they display some of the original aggression without damaging each other.

Animals which have learned to ritualise their aggression still have a need for it though, such as when they meet strangers. A wolf pack cannot grow unreservedly. While members of a small group have a better chance of acquiring food than a lone wolf, a huge pack would contradict its own interests. This means that wolves are very keen to chase non-pack members away.

Very aggressive animals need to know each other individually. For example, it could be a fatal mistake to attack a superior conspecific more than once. The rituals that two individuals perform are unique to both, and thus they come to know each other. Other animals that live in groups, like rats, do not know each other individually - they only know whether or not they belong to the same group. Rats lack the rituals we see among other animals such as wolves, dogs, geese, chimpanzees and humans.
 

Aggression does not only lead to agonistic behaviour; it is the reason for the bond between individuals. How aggressive a species or population is, is determined by selection. In a society where all individuals are aggressive, a peaceful mutant will have greater chances of survival since it will not fight with others as often as aggressive individuals. In a population of peaceful individuals, an aggressive mutant will have a better chance, since it will win all the fights it has. The quantity or the lack of aggression in a population is a result of many factors, all concerned with self-preservation. No animal is only aggressive and no animal is totally devoid of aggression. Aggression is a quantitative trait, depending on the benefits for that individual under specific circumstances. The individual that has the greatest chance of survival also has the greatest chance to mate successfully and have offspring that will inherit 50 per cent of its traits.

The aggressive dog bares its teeth. If it is dominant as well, i.e. self-confident, it will have raised ears, curled lips, a well-defined stop, staring eyes and will make its body appear large and stiff. If it is submissive, i.e. insecure, it will flatten its ears, draw back its lips, flatten its forehead and narrow its eyes. It will crouch to make its body appear as small as possible and may creep along the ground. How obvious these signals are and when they are shown together depends on circumstances, rank order and so on.

Aggression is not a disease, but it can be the cause of pathological behaviour. If an individual shows aggression, which has qualitative and/or quantitative differences from the average for that species and population in a certain period of time, it can be considered abnormal behaviour. Certain dogs show exaggerated aggression in situations where other dogs would be unresponsive. If we don't treat this behaviour in good time it can develop into pathological behaviour. Aggression may then be elicited by factors, which wouldn't normally result in such behaviour.

Aggression varies in intensity and this can be seen clearly in the dog's facial and bodily expressions.

AGONISTIC BEHAVIOUR, FEAR, DOMINANCE, SUBMISSION, DRIVE, RITUALS, SOCIAL ANIMALS, GREETING, SELECTION, PATHOLOGICAL BEHAVIOUR.
 
 

Allelomimetic behaviour

Allelomimetic behaviour is contagious behaviour, i.e. behaviour which influences another to do the same.

Dogs commonly show allelomimetic behaviour. It is often advantageous for social animals to display this sort of behaviour. In prey animals like deer, zebra or wildebeest, one individual has the ability to trigger the whole herd to flee. This trait is so important for self-preservation that farm animals like sheep, cows and horses still retain it. Social predators show these traits for hunting purposes. If one member of the pack suddenly runs after possible prey it is likely to trigger the same response in the whole pack. The wolf's howl may also be considered allelomimetic. When one wolf begins howling, the whole pack joins in, in chorus, especially if a high-ranking wolf has initiated it.

Dogs clearly show allelomimetic behaviour when they bark because the neighbour's dog is barking, or when they run after playing children.

Copyright: Roger Abrantes