A new study has confirmed that a naturally present chemical in men's sweat may act as a primitive love potion that increases their attractiveness in women's eyes.
The substance is derived from the male sex hormone testosterone.
To reach the conclusion, Tamsin Saxton of the University of St Andrews studied the influence of androstadienone by dabbling a drop of it on the upper lip of 50 women who took part in the evening trial before they "dated" a series of men.
"For some of the women we gave them androstadienone and we put it in clove oil solution so they just smelt clove oil. Some of the women had clove oil alone, and the third group had just water so there was no odour at all," she told the British Science Festival.
"We got the women to mark how attractive they thought the men were on a one to seven scale after they interacted with each man," she said.
"We found that the women given androstadienone had given slightly higher ratings of attractiveness to the men. That suggested this constituent of sweat does seem to have some kind of impact on attraction," she told the festival.
"Some people don't seem to be able to smell it all, some people say it smells OK or a bit sweaty, whereas others say it smells really awful, like babies' nappies," Saxton said.
According to the expert, one hypothesis is that it could be a "pheromone", or chemical messenger that acts between individuals in much the same way that hormones act as messengers within the body.
"It's something that people investigate on the topic of pheromones. When you talk of animal pheromones, they are involved in very specific reactions," Saxton said.
"People do value somebody's natural skin smell and it's worth bearing in mind that this may be part of your appeal - how you smell naturally," she told the festival.