A myth is busted: Testosterone not tied to aggression

A new study challenges the common belief that testosterone causes aggression in humans and proposes instead that the hormone encourages status-seeking behaviour, the journal Nature reported.

The study involving 120 women, also showed that folk wisdom about the effects of the sexual hormone is so strong that people behave more aggressively if they believe they have been given a dose even if they have not, the journal said.

Testosterone is a steroid hormone secreted by the male testes and to a lesser extent by the female ovaries that affects brain development and sexual behaviour. Research has found that it leads to a substantial increase in aggressive behaviour in rodents.

“Folk wisdom generalises and adapts these findings to humans, suggesting that testosterone induces antisocial, egoistic, or even aggressive human behaviours,” says the study published on Tuesday.

This wisdom has even reached the courtrooms because steroid-induced rage has been used as legitimate legal defence in the United States, it says. But research by the universities of Zurich and London shows that the steroid does not have the same effect in humans as it does in animals, it says.

The women, some of whom were administered testosterone and some a placebo, took part in an experiment in which they had to bargain to receive money. Common opinion would have held that subjects who received testosterone would have adopted aggressive, egocentric and risky strategies, regardless of the consequences, experts said.

“The study’s results, however, contradict this view sharply,” the statement says. “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.”

This suggested that subjects who received testosterone placed a higher value on social status than those who had taken the placebo, with the hormone increasing the sensitivity for status, it says. “The preconception that testosterone only causes aggressive or egoistic behavior in humans is thus clearly refuted,” adds neuroscientist Christoph Eisenegger from the University of Zurich.

For animals with simple social systems, an increased awareness for status may express itself in aggressiveness, the researchers add.