Testosterone – the hormone of aggression?

testosterone and aggression

Testosterone deserves a special approach. Studies on the impact of this hormone on the aggressive behavior are being carried out for centuries. It is well known that, in animal world, for example in birds, the individuals who have a higher level of testosterone behave more aggressively and they can even attack their brothers; they are more combative, more sexually active and bolder in claiming or searching for food [Müller et al., 2014].

When it comes to human species, the important role of testosterone in forming the aggressive and dominating character, especially in men, has been proved [Mazur, Lamb, 1980; Mazur, Booth, 1998; Archer, 2006]. In one of the studies, it has been found that the level of testosterone in delinquents that have been convicted for crimes that implied unprovoked violence is higher than in those who have been convicted for nonviolent crimes, and this trait is characteristic both for men and women [Kreuz, Rose, 1972; Dabbs et al., 1988].

As regarding the impact of testosterone on the induction of a deviant behavior, the Evolutionary Neuroandrogenic Theory has been proposed, which states that the masculine sexual hormones (androgenes), testosterone in the first place, have a specific influence on neural processes, are responsible for a competitive behavior and create a predisposition towards criminality. These types of behavior have evolved especially in men, in order to boost their ability to obtain resources, social status and sexual partners [Ellis, 2003, 2004]. It is why the usage of medical or sportive drugs that contain testosterone (Anabolic Androgenic Steroids) could develop a higher aggressiveness among men, which leads to the fact that they get engaged more often in violent acts [Pope et al., 2000; Beaver et al., 2008].

It is important to stress that the high level of testosterone will not always cause a violent, egoistic and antisocial behavior, towards the members of one’s own group. When their native group is engaged in a competition with a foreign group, the effects of testosterone are completely different and men will display the so-called „parochial altruism”: the favoritism and in-group cohesion, as well as out-group hostility will increase.

Men with a high level of testosterone in their blood will suddenly become more generous towards their group members and, at the same time, more aggressive towards the foreign rivals; they will be more willing to risk for the sake of their group, to engage in competition and fights for the common good and to punish those who cheat or refuse to fight for the group’s cause. This altruist behavior of self-sacrifice usually applies only to competition and intergroup conflicts. Therefore, testosterone does not necessarily induce antisocial attitudes and actions, but is rather involved in a much more complex behavioral mechanism, which has an adaptive role [Diekhof et al., 2014].

We also have to understand that the effects of testosterone on behavior are not unidirectional; the testosterone does not necessarily raise the overall level of violence, but rather the motivation of individuals to assert themselves and to compete for a higher social rank. And it already depends on the personality of the individual and his lifestyle whether this rank can be obtained by means of violence or other, more intelligent, methods.

Psychologists have examined the criminal incidences of 4.462 men whose level of testosterone was measured way back when they served in the army. They have found out that the level of testosterone is strongly associated with an antisocial behavior, but only in individuals who were living in unfavorable social conditions. More exactly, from the same sample of people with high level of testosterone, the educated individuals from the upper classes were able to ensure a high social status by means of financial, academic, political and bureaucratic competition, while those who were socially disadvantaged, without higher education and career, have showed they inclination towards competition in the area of criminal activities, by directly using their inner predisposition towards aggression [Dabbs, Morris, 1990].

Other studies have shown that the presence of a high level of testosterone in blood can make individuals act aggressively only when injustice is done. Particularly, experiments carried out on women have shown that testosterone could be associated with the desire for justice and righteousness in social relationships [Burns, 2011]. What we do understand is that the environment and social context partially affect the parameters of the manifestation of some predispositions that are caused by androgen hormones, by stimulating those predispositions, decreasing or redirecting them.

As a general conclusion, it appears that people who have a specific genetic or hormonal status are more prone towards agonistic behavior than their peers and that in certain social conditions it is harder for them to control their impulses. Therefore, it is no wonder that predictions regarding the behavior of individuals can be made based on the analysis of their hormonal content.

Thus, in a research that has been carried on male minors, the salivary concentration of three hormones has been carried out: testosterone, cortisol and dehydroepiandrosterone, and the results have shown a clear correlation between the concentration of these hormones and aggressiveness; the minors who had a higher salivary concentration of these hormones demonstrate a higher degree of aggression [Barzman et al., 2013].

However, things are more complicated with cortisol; a study that was carried out on 78 youngsters has found out that the level of cortisol was lower in the saliva of those who were more sexually aggressive [Peterson et al., 2014]. Finally, some subtleties of the hormonal status’ relation with aggressiveness are still to be clarified, so that more pertinent conclusions could be drawn.


© Dorian Furtună, ethologist

Photo: You are wrong / Flickr / https://www.flickr.com/photos/digitalgrace/90705344/

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