British Psychological Society: Sex appeal? It's all down to smell

IT HAS been called the battle of the sexes but now it seems women really do use "chemical warfare" to trick men into believing that they are more attractive than they appear.

Female pheromones - airborne chemical messengers - may have evolved so that they can block a man's ability to judge a woman's attractiveness on the way she looks and the sound of her voice, scientists told the British Psychological Society's London conference yesterday.

But for women taking the contraceptive pill, the biologists from the University of Vienna had bad news - the Pill blocks the production of these useful pheromones.

The chemical signals, which affect behaviour and are often used by animals to attract mates, act as a love potion, attracting the man to a woman, although on the basis of sight and sound alone he might not have been interested in her.

There are about 240 different pheromones but only 15 to 20 have as yet been tested. In this study, the scientists exposed a group of 66 young men unknowingly to synthetic vaginal pheromones called copulins. Their reactions to photographs of women and to female voices were compared with what happened when the pheromones were replaced with ordinary water.

When the men had been exposed to copulin they rated the voices and faces as more attractive. Crucially, it equalised previous differences. The less attractive the woman was rated before, the bigger the rise in her perceived attractiveness when the men had been given copulin. "The more negative a woman was rated in attractiveness without smell, the more she gained through smell," Professor Karl Grammer said.

He added that the explanation was likely to be an evolutionary one. "[The pheromones] make all females equal," said Professor Grammer. "Women have learned to exploit men for their own advantage ... There is a lot of communication going on at a level we are not conscious of."

He also said that the amount of testosterone in the men's saliva increased after they had inhaled the pheromones. Merely by smelling the pheromones the men's ability to process information from their eyes and ears was altered.

Women also altered in the amount of pheromones they produced depending on the stage in their menstrual cycle, producing most as they approached their most fertile time.

But the professor warnedwomen who took the Pill, which inhibited copulin production: "This could have a negative effect on your sexual life."

Another study carried out at the University of Northumbria found that when men and women were knowingly exposed to pheromones from the other sex and were shown a fictional description, they rated them as more sexually and physically attractive. Men were also more likely to see the female character as more likeable, but women did not see the male character as more likeable or even as more intelligent.

The presence of male pheromones made both women and men feel more energetic, and the use of female pheromones made both sexes feel more elated and confident.