Testosterone does not induce aggression

New scientific evidence refutes the preconception that testosterone causes aggressive, egocentric, and risky behavior. A study at the Universities of Zurich and Royal Holloway London with more than 120 experimental subjects has shown that the sexual hormone with the poor reputation can encourage fair behaviors if this serves to ensure one's own status.

Popular scientific literature, art, and the media have been attributing the roll of aggression to the arguably best known sexual hormone for decades. Research appeared to confirm this - the castration of male rodents evidently led to a reduction in combativeness among the animals. The prejudice thus grew over decades that testosterone causes aggressive, risky, and egocentric behavior.

The inference from these experiments with animals that testosterone produces the same effects in humans has proven to be false, however, as a combined study by neuroscientist Christoph Eisenegger and economist Ernst Fehr, both of the University of Zurich, and economist Michael Naef of Royal Holloway in London demonstrates. "We wanted to verify how the hormone affects ," Dr. Christoph Eisenegger explains, adding, "we were interested in the question: what is truth, and what is myth?"

For the study, published in the renowned journal Nature, some 120 test subjects took part in a behavioral experiment where the distribution of a real amount of money was decided. The rules allowed both fair and unfair offers. The negotiating partner could subsequently accept or decline the offer. The fairer the offer, the less probable a refusal by the negotiating partner. If no agreement was reached, neither party earned anything.

Before the game the test subjects were administered either a dose of 0.5 mg testosterone or a corresponding placebo. "If one were to believe the common opinion, we would expect subjects who received testosterone to adopt aggressive, egocentric, and risky strategies - regardless of the possibly negative consequences on the negotiation process," Eisenegger elucidates.

The study's results, however, contradict this view sharply. Test subjects with an artificially enhanced testosterone level generally made better, fairer offers than those who received placebos, thus reducing the risk of a rejection of their offer to a minimum. "The preconception that testosterone only causes aggressive or egoistic behavior in humans is thus clearly refuted," sums up Eisenegger. Instead, the findings suggest that the hormone increases the sensitivity for status. For animal species with relatively simple social systems, an increased awareness for status may express itself in aggressiveness. "In the socially complex human environment, pro-social behavior secures status, and not aggression," surmises study co-author Michael Naef from Royal Holloway London. "The interplay between testosterone and the socially differentiated environment of humans, and not testosterone itself, probably causes fair or aggressive behavior".

Moreover the study shows that the popular wisdom that the hormone causes aggression is apparently deeply entrenched: those test subjects who believed they had received the testosterone compound and not the placebo stood out with their conspicuously unfair offers. It is possible that these persons exploited the popular wisdom to legitimate their unfair actions. Economist Michael Naef states: "It appears that it is not itself that induces aggressiveness, but rather the myth surrounding the hormone. In a society where qualities and manners of behavior are increasingly traced to biological causes and thereby partly legitimated, this should make us sit up and take notice." The study clearly demonstrates the influence of both social as well as biological factors on human .

Source: University of Zurich

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Dec 08, 2009
And what is the result of high testosterone coupled with denial of the social status being sought? I think we can guess the answer to that one.

Dec 08, 2009
Next step is to isolate those whose aggression level is enhanced by testoserone and search for a genetic predisposition which is affected by increased testosterone

Dec 08, 2009
@po6ert, as far as psychosocial affairs, who's aggression level would be better to test? And what are we defining as "aggression?" If we're talking about anti-social behavior, we need to look at the limbic system and its emotional high pressure valve, the amygdala. Dr. Derrick Lonsdale has linked aggressive, antisocial behavior with high calorie malnutrition, usually relegated to poor neighborhoods and 3rd world countries.

As for myself, I've been on testosterone precursors for months. I get a little mad at times, but most of the time, people enjoy my company. I also feel like I take a few more risks than usual; risks in matters of the heart, career, finance, social status.

That extra testosterone also helps me shed extra pounds and be a "marathon man." It also helps keep up my mood and I've never caught the flu yet, so it must be helping there too.

Dec 08, 2009
for example insulin injections lead to low blood sugar, but for a diabetic this is a favorable out come. testosterone may not affect the limbic system in most individuals but ther maybe some in the population that there is an increase in aggression. I use testoterone on a daily basis, and I too show no usual aggresive tendencies.
(if you don't consider murdering a deer as agressive)
generalization are always dangerous

Dec 08, 2009
"In the socially complex human environment, pro-social behavior secures status, and not aggression,"

agression defines the boundaries and keeps players in a certain zone of behavior. within that zone, social and other more subtle issues come to play (like family history, or size, etc).

the agressiveness and such behavior in humans would be more likely if the game they set up involved cheating the test subject. then the pro social actoin is a more agressive response so as to not only stop it, but to prevent future attempts. (up and down a scale this forms a pecking order)

also. momentary actions can change the order as winning and losing can change the level.

it is interesting to note that if you apply that knowlege to what they say there. a winning man is a kinder more generous man... a losing man would lower their testosterone and would do less social postitive acts... (ie selfish)

Dec 09, 2009
Seems to me that this experiment measures logic not aggression. One could use logic to deduce that a fair offer is the one most likely to result in reward. Aggression not needed. Aggression and logic are not mutually exclusive. A person may use his aggression in a logical way to garner the best outcome. Before testing for aggression, I think we need to better define what constitutes aggressive behavior. It doesn't preclude logic.

Dec 09, 2009
The study's results, however, contradict this view sharply.
Moreover the study shows that the popular wisdom...
The study clearly demonstrates the influence...
Hold your horses, pilgrims! You have one single study, with one single amount of hormone, and one single test game.

For such ground breaking claims, it would be prudent to at least have some more research to back it up. Geez!

Dec 09, 2009
qwrede - quantity is irrelevent.. quality counts.

a million wrongs dont make a single right... do they?

and one single right, dashes all wrongs...

so your point is irrelevent...

(it applies to politics too)

Dec 18, 2009
Have to agree with Carolina Scotsman, this isn't a good test for "aggression". It is however, a good test for "manipulation".

Aggression has to do with impulse control, and unprovoked attack. A test for that would be more open-ended, set up the subjects to be frustrated and see how they respond.

Dec 18, 2009
The researchers here have my deepest sympathy. It must be terrible, to spend all one's time and energy on a study, only to have it invalidated in two seconds.

But at least we know what not to test for next time, and that's still progress.

Dec 18, 2009
I've just been doing more reading, and it seems this particular practice of measuring manipulation and then conflating that for "aggession" has been done many times before. Could you folks stop repeating bad methodology, hoping for a different result?

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