‘Sweat is sexy’ – but a smile is much sweeter.

It's not hard to spot those tell-tale signs when a man is happy to see a woman.

A twinkle in the eye, a spring in the step and a relentless smile are usually surefire giveaways.

Now, scientists are saying a women can tell when a man is interested in her, at least subconsciously, by the smell of his sweat.

Tests conducted at Texas’ Rice University showed that women reacted differently to the underarm sweat of a man feeling frisky and a man going about his day-to-day activities.

The results have prompted researchers to suggest that human beings use pheromones to subconsciously communicate with one another, much in the same way animals do.

In the tests, sweat was collected with polyester pads attached to the armpits of men. One sample was collected whilst the test subjects watched an educational film for 20 minutes, whilst a second sample was collected whilst they watched pornographic material. The two samples were then compared.

Nineteen women in their 20s were subjected to the samples, and all responded subconsciously to the different smells.

Their brain waves were monitored with functional magnetic resonance imaging.

Professor Denise Chen, who led the study, said that the “sexual” sweat lit up different regions of the women’s brains, suggesting that the female brain can recognise the smell of a man who is attracted to her.

Francesca Johns, a 21 year-old administration assistant from Lincoln doesn’t think a woman should rely on her subconscious to determine whether or not a man fancies them.

“There are much more reliable ways you can use to gauge if a man is interested in you or not,” she said.

“Eye contact is usually the best way. If he looks directly at you whilst he’s talking to you, then you know the evening’s probably going to have a good chance of success.

“Other than that, if he makes slight physical contact, then you know he’s definitely interested. A slight brush of the hand or something like that.

“What’s the point in relying on pheromones, which may or may not exist in human beings, when you can’t consciously decode them anyway?”

John Barraclough, a 22 year-old television salesman based in North Hykeham, agreed with this point, saying a man would not usually try to hide his intentions anyway.

“It’s all very well and good talking about pheromones and the effects they might have,” he said.

“But if a man is interested in a women, he’s going to let her know about it.

“She’s not going to have to rely on some cryptic code which needs figuring out, or some subtle signals.

“The general rule is, if you’ve had to spend time trying to figure out whether or not a man is interested in you, then he’s probably not.”