TESTOSTERONE is a hormone with a reputation. Though both sexes generate the stuff, that reputation is macho. Numerous experiments on non-human animals show that boosting testosterone levels boosts levels of aggression. And in most species—humans included—males are the more aggressive sex.
Doing experiments specifically designed to increase aggression in people is ethically problematic. Aggression is not, however, the only behavioural trait that seems to differ between the sexes. Generally speaking, males are also more impulsive than females. And that, too, may be linked with testosterone levels—a link that Gideon Nave at the University of Pennsylvania and Amos Nadler at Western University in Ontario have recently been exploring.
Impulsiveness can be measured in many ways. That chosen by Dr Nave and Dr Nadler was mathematical. In the largest experiment yet conducted on the effect of testosterone on human behaviour, which they have just reported in <em…Continue reading