Testosterone makes men wimps, while oestrogen, the female hormone, may be the culprit behind human aggression.
First identified nearly half a century ago as the androgen that makes men manly, testosterone has had a bad press. This lone chemical is routinely blamed for many of society's ills, including wife beating, bar-room brawling, loud public burping, speeding, hair loss and Mike Tyson.
But scientists at the University of California have concluded that male antisocial behaviour may be the result of too little testosterone, rather than too much. The scientists studied 54 men with abnormally low testosterone levels and found that, instead of leaning toward "sugar and spice and all things nice", the men were uniformly grumpy, paranoid and pugnacious.
When their testosterone levels were artificially raised, their spirits lifted and they stopped wanting to thump each other.
"The positive mood increased, the negative mood decreased. Every parameter we looked at went in the same direction," Dr Christina Wang said.
Both sexes possess male and female hormones, and other studies have prompted the unlikely conclusion that oestrogen, the female androgen, may be the root cause of much antisocial behaviour.
When male laboratory mice were genetically deprived of the ability to respond to oestrogen by scientists from Rockefeller University and the National Institutes of Health they became more laid-back and sociable.
The male mouse is highly territorial and tends to patrol the edges of open spaces such as fields, attacking any intruders. When deprived of oestrogen receptors, however, the mice became timid toward fellow rodents and tended to stay in mid-field, trying to avoid confrontation.
So the hoary old cliche of the aggressive male, pumped up with testosterone and looking for a fight, may have to be replaced with another image: the macho male just too much of a woman for his own good.
While testosterone may not make men fierce, it certainly improves the sex drive. The 54 male patients with low levels reported feeling little interest in sex but became more perky after a dose of extra testosterone.
- The Times