Last Updated 23 Jun 2020

Human aggression

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Human aggression is innate; others say that it has biological roots. Looking at the biological standpoint, similarities between non-primate, animal aggression and human aggression seem to present that human aggression stemmed from animal aggression. Testosterone levels in animals, which are related to aggression, also seem to contribute in the aggressive behavior of animals. This, however, is not the case. Considering another biological aspect, the neurology of humans, seems to play a crucial role in human aggression.

However, the arguments presented by the view that human aggression has biological roots are not entirely without fault and repercussions. Biological Roots of Human Aggression The meaning of human aggression varies from person to person. Human aggression is the competitive form of social behavior among Homo sapiens (Go, 1983). It is also defined as the behavior wherein the underlying objective is to cause pain, harm, physical distraction or injury (Net Industries, 2008; Baron & Richardson, 1994).

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Using the definition of aggression in which pain or harm is the motive to act violently or hurt others and the self, aggression may be classified in several ways. Aggression may be classified as either passive or active. It may also be categorized as direct or indirect, physical or verbal or any combination of the three classifications (Net Industries, 2008). Some also classify aggressive behavior into three – social aggression, predatory aggression and threatening aggression. Social aggression is considered as unprovoked aggression towards another for establishing power and dominance.

Predatory aggression refers to killing and murder. Threatening aggression pertains to attacks delivered when an aggressor is present (Schaffhausen, 2008). In a way, the classifications narrow the definition of aggression. The subject of human aggression has been the topic of debates, especially its cause (Go, 1983). Some suggest that human aggression is innate and cannot be changed. They believe that aggression is within humans and that humans respond to it naturally and spontaneously by releasing aggressive energy.

If this energy is not released, humans explode into violence. This implies that releasing aggressive energy in a constant and healthy manner would make humans less aggressive since their aggressive energy is dissipated part by part. It also implies that aggression can be purged out of a human being’s system by continuously engaging in activities that vent out the aggressive energy such as sports (Kohn, 1988). However, the theory of aggression as innate is being critically questioned, especially by the Seville Statement.

It states that it would be scientifically incorrect to say that human beings have inherited the aggression present in animals. It is also scientifically incorrect to state that aggression is embedded in the genetics of humans. There have been no scientific evidences showing that genes produce individuals that are predisposed to violence. It is also not correct to say that aggression is caused by instinct or just a single intent (Spanish National Commission for UNESCO, 1986). To debunk the theory that aggression is innate, others say that it is due to some biological causes.

To understand the roots of human aggression from a biological perspective, scientists study the behavior of the origins of the humans. This is because human aggression has a number of substantial features similar to animal aggression. Surviving in the wild has become a necessity for animals. Human aggression has stemmed from that also; it became normal because of the need for survival and adaptation (Gordon & Smith, 2000). Also, similar to animal aggression, human aggression is present at all age levels and is displayed by both male and female.

It is also not dependent on seasonal changes and in fluctuating hormone levels or pragmatic events like sexual activity. These data support the inference that human aggression has its roots in the defensive aggression of non-primate animals (Alber, Jonik & Walsh, 1993). One of the earliest attempts to discover the biological roots of human aggression occurred in the 1960s. The researchers tried to link human aggression to genes by considering the extra Y chromosome in males. The researches thought that the extra Y chromosome gave males more inclination towards violence and aggression.

However, this was not the case and the studies shown that there was no significant difference between males with the extra Y chromosome (Schaffhausen, 2008). The origin of human aggression, from a biological view, was then inferred from studies of the testosterone levels of non-primate animals and its affect in the animals’ aggression. Testosterone is linked to social aggression in animals. Reducing testosterone in the male leader or a male of high position by castration eliminates the male’s dominant social status.

But restoring testosterone by means of injection may allow him to regain his social status as the male leader. However, there have been studies that show that the correlation between the testosterone levels in animals has no bearing in humans. Testosterone levels between high-physical aggression and low-physical aggression do not have a significant difference. This is also supported by the fact that physical aggression does not increase during puberty wherein the testosterone levels of both males and females dramatically increase.

Also, castration and anti-androgen administration, in which testosterone levels decrease, does not correspond to a significant decrease in aggression (Alber, Jonik & Walsh, 1993). The neurological roots are also necessary to understand the biological roots of human aggression. The brain activities of a group of adolescent kids, considered as reactively aggressive, were studied to determine the neurological processes related to aggressive behavior. At the exact moment when the boys have reacted aggressively, the teenagers seem as if they cannot help but do so, at least for the moment.

To monitor their brain activity at the precise moment of aggression, researchers used a functional magnetic brain imaging. They also deduced that similar to aggression, fear is considered as a trait, which appears to teenagers at an exact moment, and the teenagers cannot help but feel fear given certain stimuli. In the study, the stimuli used were images of threatening faces. Using the brain-imaging instrument, the amygdala, the part of the brain associated with fear, had a significantly greater activity and the prefrontal cortex, the part of the brain involved in decision making and reasoning, had a relatively lower activity.

This indicate that that affected teenagers feel fearful, as implied by the overactive amygdala, but have less capacity to control their reactions, due to a less than reactive prefrontal cortex (Singer, 2007). The study points to the prefrontal cortex as the part of the brain involved in aggression and violence. However, other studies also support that the prefrontal cortex is related to aggression and violence. EEG and other instruments for monitoring brain functions have long suggested that violent criminals have impaired neurological processes (Singer, 2007).

A study, using positron emission tomography, monitoring brain activity of murderers and anti-social people, people considered as having relatively aggressive traits, as subject showed that the subjects’ prefrontal cortices were significantly smaller and there was also heightened activity in the sub-cortical regions such as the thalamus. A meta-analysis also showed the same results. It also showed that people with a history of violent behavior have functional and structural impairments in the prefrontal cortex, which impairs the decision-making and increases impulsive behavior (Raine, Buchsbaum, & LaCasse, 1997).

Other neurological studies show that serotonin may play a key role in aggressive and violent behavior. Serotonin is the neurotransmitter in the brain that plays a key role in processing emotions and sleep. It transmits nerve signals between the nerve ends and acts as a chemical messenger as well (Schaffhausen, 2008; Mann, 1999). Experiments show that enhancing the level of serotonin leads to a reduction in aggressive behavior. It also shows that knockouts of certain serotonin receptors cause an increase in aggressive behavior of mice. Decreasing levels of serotonin also shows an increase in aggression of vervet monkeys.

Because of the similarities of aggression between animals and humans, the connection between serotonin and aggressive behavior in humans was studied. The studies regarding humans showed that serotonin is related to human aggression. People with history of violent and aggressive behavior such as violent criminals show low levels of serotonin in their cerebral spinal fluid. The studies also show that serotonin related inductions in aggressive psychiatric patients led to reduction in violent outbursts and hostile sentiments. Neurosis is also linked to the cause of human aggression, based from the biological outlook.

Neurosis consists of acts that cause significant harm to other people as well as the self. Neurosis, however, is brought about by the frustration due to obtaining the basic human needs (Wollstein, n. d. ). However, the claims that human aggression is caused by biological causes are not without faults and repercussions. Human aggression, although it has similarities with animal aggression, is not necessarily the same. For one, drawing conclusions from the aggressive behavior of animals to state arguments about human aggression is not correct.

The force of culture and society and the human being’s capability to think and reason out sets a big difference between human aggression and animal aggression. In addition, animal aggression may not be in the same context as human aggression. Aggression that is carefully planned rarely occurs in animals as compared to humans, except when it comes to killing for food (Go, 1983). In addition, extremes were present in some of the studies done to show that the amygdala and some other parts of the brain are related to aggression.

Using murderers and psychiatric patients represent the extreme end of human aggression. Aggression may also be done in means less violent such as punching a person or beating up a person. There are also plenty of people who may have brains with damaged prefrontal cortex but do not inevitably show aggressive behavior or commit violent, or possibly, hideous acts. Using instruments for mental activity and brain imaging such as the PET scans cannot be automatically used to support the claim that the prefrontal cortex is associated with human aggression (Singer, 2007).

Moreover, as interesting as the findings regarding the neurotransmitter serotonin may appear to be, the direction of the effect is not clear. Aggressive behavior could possibly be the effect of a decrease in the serotonin levels or vice versa, the serotonin levels decrease because of the aggressive behavior. Testosterones are also not very good indicators of aggression. Some evidence is present that males with high testosterone levels are more likely to be socially aggressive compared to ones with lower levels of testosterone but there is no proof that these men are necessarily more violent.

These men are usually in the top of the corporate ladder are competitive ones. Women, who are typically associated with having low-levels of testosterone, might not necessarily be less aggressive than men. Women engage more in non-physical aggression. Thus, the testosterone levels may indicate that it has no connection between physical aggression but the other forms of aggression cannot be clearly deduced from the testosterone levels present in a human’s body (Schaffhausen, 2008).

However, even though researchers have successfully linked some of the biological factors such as serotonin, etc with human aggression, they have yet to figure out if these are the concrete biological roots that cause aggressive behavior in humans. There are no neurological markers that might determine which people has more aggressive tendencies or when an aggressive behavior is determined by the mind. The brain has yet to be completely figured out and definitive tests have yet to be managed and done.

Also, different forms of aggression, other than physical aggression, are yet to be linked to some of the biological links being studied by researchers (Schaffhausen, 2008) The scientific agreement regarding aggression is that it is a combination of many different factors. The biology part related to aggression – the amygdala, the limbic system, the hypothalamus, etc. only plays a small role in aggressive behavior (Marsh, 1984). References Alber, D. J. , Jonik, R. H. , & Walsh, M. L. (1993) Aggression in humans: what is its biological foundation? Neuroscience and Biobehavioral Reviews.

17(4):405-25. Vancouver. Baron, R. A & Richardson, D. R. (1994) Human Aggression. (2nd Ed. ) New York: Plenum. Go, J. L. (1983). Aggression. In Funk & Wagnalls New Encyclopedia. (Vol. 1, pp. 236-237). Rand McNally & Company. Marsh, F. (1984)Biology, Crime and Ethics: A Study of Biological Explanations for Criminal Behavior. Anderson Pub Co Gordon, L. & Smith, D. (2000). The Nature of Human Aggression. Retrieved April 6, 2008, from http://jrscience. wcp. muohio. edu/reflections/FinalArticles/TheNatureOfHumanAggressio. html Kohn, A. (1988). Are Human Innately Aggressive?

Retrieved April 6, 2008, from http://www. alfiekohn. org/miscellaneous/aggression. htm Mann, JJ. (1999) Role of the serotonergic system in the pathogenesis of major depression and suicidal behaviour. Neuropsychopharmacology, 21 (2): 99S-105S. Net Industries. (2008). Aggression – definition. Retrieved April 7, 2008 from http://social. jrank. org/pages/25/Aggression-Definition. html Raine, A. , Buchsbaum, M. , LaCasse, L. (1997). Brain abnormalities in murders indicated by positron emission tomography," Biological Psychiatry, 42: 495-508. Schaffhausen, J. (2008).

The Biological Basis of Aggresssion. Retrieved April 6, 2008, from http://www. brainconnection. com/topics/printindex. php3? main=fa/aggression Singer, E. (2007). The Neurological Roots of Aggression: Recent findings shed light on the brain deficits that underlie aggression and could aid in the development of preventative treatments. Retrieved April 6, 2008, from http://www. technologyreview. com/Biotech/19679/ Spanish National Commission for UNESCO. (1986). The Seville Statement on Violence. Retrieved April 8, 2008, from http://en. wikipedia. org/wiki/Seville_Statement_on_Violence.

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