Testosterone, the so-called macho hormone, actually promotes reasonableness and fair play, a new study claims.
Scientists found that giving people a testosterone boost in the shape of a pill made them more likely to act in a friendly and altruistic way.
They claim the results finally dismiss the myth – sometimes even used in court – that the sex hormone testosterone is the cause of much male aggression and anti-social behavior.
However the popular belief that it makes you more ruthless and rebellious is so strong that if people believe they are taking the hormone they tend to fulfill their beliefs.
“This shows that the popular belief that testosterone makes you aggressive is inaccurate, ” said Michael Naef, at the Royal Holloway Hospital, north London, where some of the research was carried out.
“People use it as an excuse. It appears that it is not testosterone 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.”
Mr. Naef said it was more accurate to describe testosterone as the “status” steroid.
In places like prison – where it was survival of the toughest – then it promoted aggressive behavior as that was the only way to increase social standing.
However in normal life the opposite was true – as friendliness and co-operation boosted your position in society.
Mr. Naef, and scientists from the University of Zurich, who published their findings in Nature, tested the theory on a group of 121 volunteers.
Half the group were given a testosterone pill, and the other half a placebo. They were not told which was which. They then took part in a behavioral game which involved the sharing out of money.
The rules allowed for both fair and unfair sharing by a proposer whose actions could be rejected or accepted by a receiver. If they could not agree to share then no one got the money.
The findings showed that those that were given the testosterone were more likely to propose fair offers of sharing and more likely to be co-operative even if it the sharing seemed unfair.
Dr Christoph Eisenegger, a neuroscientist, said: “The preconception that testosterone only causes aggressive or egotistic behavior in humans is thus clearly refuted.”
However in a separate test, if the volunteers were told they had been given testosterone then they did act in an aggressive and anti-social way.