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The Cause of Aggression

Vicky Tu's picture

 There has been an enormous amount of violence committed by humans throughout our history, like the Nazis, serial killers, or simply the abusive husbands. The questions are: What causes all these atrocious behaviors? What is going on in the brain of these people as they cruelly push a knife into the flesh of another innocent human being who looks and thinks like themselves? Is it in all of us to commit such crimes? Finding out the answers to these questions is essential to the future prevention of violence.

Alcohol has been a universal cause of aggression. I am currently taking a Russian folklore class in which I am learning about many aspects of the life of Russian peasants in the older times. Apparently the husbands beat and tortured their wives brutally when drunk yet they could act very affectionately to their wives when sober. This is an example that demonstrates the cause-and-effect relationship between alcoholism and violence. When the amount of alcohol consumed by a person exceeds the amount oneÆs body can tolerate, the alcohol can cause an increase in excitability by decreasing inhibitory inputs. It changes the activities of some chemicals in the brain like ?-aminobu¡ tyric acid (GABA) and serotonin, which are all chemicals related to violence. The complete effects of alcohol in the system is very complicated and yet to be discovered. But it is certain that it can cause aggression by changing the level of neurotransmitters that are related to violence. In fact, many Nazi German soldiers confessed that they relied on alcohol ôto boost up their courageö to perform genocide during the Holocaust.

Besides alcohol, two other important factors may cause aggressive behaviors: influences from the environment and ôviolentö gene. The influences from the outside environment include abusive family, neglected childhood, or poverty. The ôviolentö gene causes a natural-born tendency for a person to turn violent. Serotonin is the main neurotransmitter that controls and inhibits violent behavior and depression in a negative environment. Study has shown that people with a low serotonin level in their cerebrospinal fluid has a high tendency to attempt a violent suicide and to have long-term aggressive behaviors. The conditions of these neurotransmitters are usually passed on genetically. They are determined by gene expressions. Yet gene expressions can be altered by the way an individual animal is brought up and the environment the individual grows up in.

The parts of brain that control violent behaviors seem to be pre-frontal cortex and sub-cortex. The former regulate decision-making and social behaviors. The later moderates many basic body functions and information processing. The people who display violent behaviors have a lower than normal activity level in their pre-frontal cortex and a higher activity level in their sub-cortex.

The brain is such an intricate ômachineö that it is still very hard to determine the detailed cause of aggressive behaviors. Is it in all of us to commit atrocities? Actually, it could. Even though genetically ônormalö people have low tendency to turn violent, they are capable commit atrocities when the level of their serotonin or other neurotransmitters change when extreme situations occur. During the Holocaust, many of the Nazi German soldiers were actually common people with a well-rounded education background and good family.  Due to the pressure from the authority and peer pressure (fear of being called a coward), they went against their conscience and committed one of the biggest crimes in the world. This shows that normal people could turn violent in extreme circumstances.  This is why we need to create a peaceful, loving, and alcohol-free environment for our future generations.



(1) Alcohol Research & Health

(2) The Journal of Neuropsychiatry and Clinical Neurosciences

(3) Sciencentral Archive



Paul Grobstein's picture

aggression, alcohol, and the brain

"we need to create a peaceful, loving, and alcohol-free environment for our future generations."

In some contexts, alcohol contributes to "peaceful, loving," no?  And certainly some violence is committed without it.  So maybe we need acknowledge that neither alcohol nor any thing else is a "detailed cause of aggressive behaviors"?  And perhaps even that "agressive behaviors" themselves are desireable or undesireable in different contexts?  Not all aggression results in murder.  And some is pursued in the interests of creating "peaceful, loving" environments.