This is based on the theory that everything human beings do would have to be learned from other human beings. Aggression must be learned as we grow. It is not just simply there from the moment of birth. A person behavior is something that is taught to him rather than being an unmanageable instinct. For example, a newborn baby is breathing because it is an uncontrolled reaction. But on the other hand, a father may tell his young son to beat up the school buly who is picking on him. As a result, the boy is dealing with the situation by using violence.
In order for a human being to display aggression, violence and anger, it must be driven by an instinct interacting with that persons surroundings. The word instinct is defined as an inherited or innate psycho-physical disposition which determines its possessor to perceive, and to pay attention to, objects of a certain class, to experience an emotional excitement of a particular quality upon perciving such an object, and to act in regard to its particular manner, or, at least, to experience an impulse to such action. This definition, explains that people have different reactions for different situations they are put in. Therefore, an individual is expected to act a certain way when he is encouraged to do so from his surrounding environment. For example, an Eskimo does not have an inborn instinct that allows him to survive in his climate. He has to work with his people in order to survive when he is at a very young age.
Furthermore, when people are brought up in a society, they learn a certain way of life and traditions. These customs are usually taught to them because its part of their societys way of life, even if some of the customs may be brutal and horrible to others. For example, cannibalism is distasteful to us, but in some prehistoric cultures, to eat an enemy is to gain his or her strength. This aggressive behavior was taught to the people of this culture and is the cause for its existence. People need to have contact with aggressiveness in society in order to act aggressive. For example, there was a tribe in New Guinea, who were violent warriors that were always fighting and killing each other.
The children of these people learned this aggressive act from their parents and then acted in the same way. A parents method of child rearing has a huge impact on the childs aggression. For example my own brother found a way, which will convince my parents to buy him what he wants. All he has to do is cry and if he doesnt get what he wants he will start smashing, kicking and throwing thinks that he find around him.
Moreover, when a group of people are isolated, their behavior does not change unless they interact with other people. There was tribe made up of a group of people who were completely isolated fro the rest of the world. They did not show any signs of aggression due to the fact that they had no words for weapon, aggression, anger or war. All they did was gathering food. So the tribe and had no use for weapons. The tribe only used knives and other things that might be thought as weapons or tools to gather food. They even rejected the spear, the bow and arrow because they could not use them to gather food. There could not been anything in their genetic makeup that made them act in an aggressive or peaceful manner. This was just their way of life that was taught from generation to generation, to gather food which was needed to survive.
The source of human aggression lies in factors such as society and culture. Aggression is a learned emotion that is built up on different factors in a persons surrounding environment. It the combination of environment, society and culture that creates aggressive behavior. It is the persons instincts that are the basis for the three. While one tribe is a peaceful group of people, and the other a group of aggressive warriors. Both of the tribes had the ability for aggression and peaceful life but it was their environment, society and culture that have driven them to choose totally opposite paths.