Lip-gloss at the ready, it’s February and that means Valentine’s Day and a great excuse for a guilt-free snog! Before you get your smackers moving take a moment to think about the famous words of Rudy Clark (and the dulcet tones of Betty Everett and Cher)… It’s in his Kiss. But what exactly is IT? In the harsh light of day kissing is weird – I mean, why our mouths? They are full of germs! Why not an elbow rub? An ear wiggle? Scientists here in Oxford are on a mission to find out.

Humans kiss, A LOT! Our relatives the chimps and other primates also kiss, though not as obsessively, so it is likely that it is something we have always done. The fact that so many people do it means there is also probably some evolutionary purpose. Scientists are looking at three main theories about our kissing compulsion.

The first theory is that kissing is designed to get us ready for the main game – sex. The act of kissing stimulates hormones that arouse us in all the right ways and places. In a survey, conducted by Rafael Wlodarski and Prof Robin Dunbar at the University of Oxford Department of Experimental Psychology, they found that people tend to kiss most before they have sex. But we do like to kiss even when we aren’t that interested in sex. So there must be more to it.

It seems that women think that kissing is an important part of maintaining a stable relationship. Theory number two is all about durability – that kissing is a show of affection that reinforces our commitment to a long-term partner.

The survey showed that couples who kissed a lot also reported being happy more often. The final theory that is gaining suction is that we kiss to assess a potential mate.

We humans are giving off chemical signals like pheromones (hormones that smell) all the time through our skin, urine, sweat and… well, most of our bodily fluids. By kissing it seems that we can sense a lot about the suitability of a mate including their health, immunity and potentially even their genetic suitability.

We don’t fully understand this, nor do we know what chemicals might be at play. Hormones are likely candidates, particularly things like testosterone. Women have been found to prefer the smell of men who have high levels of testosterone and the mouth may be one measure of a man’s testosterone levels. Wlodarski and Dunbar’s research suggests that our natural desire to kiss is probably down to a combination of all three theories – we kiss to test the talent, to enable us to perform in bed and to hang on to our chosen mate.

Whether you are looking to be swept off your feet or to croon starry-eyed at your long-time love, be comforted by the fact that Cher and the scientists agree.

You should certainly consider what’s in his kiss.