EVEN OUR SALIVA IS DIFFERENT . . .

THE composition of men’s and women’s saliva is also different, which means kissing is not only romantic, it also transmits important information about how good the kissers are as potential mates.

A woman’s saliva changes throughout her menstrual cycle and her kisses tell the man about her fertility.

Around ovulation, it contains more sugar and her kiss is sweeter — this was possibly an evolutionary tool to encourage mating at the time when chances for impregnation are highest.

Meanwhile, the testosterone a man passes through his saliva is meant to signal his sexual prowess and enhance a woman’s willingness to have sex.

In addition, it is likely that a woman can subliminally ‘read’ her partner’s saliva to determine the robustness of his immune defences.

A 2007 U.S. study found that more than half of women attracted to a particular partner discontinued contact after a few kisses.

The study, reported in the journal Evolutionary Psychology, suggested that the most likely reason was the woman had unknowingly assessed the man as incompatible healthwise, rather than judging him to be a poor kisser.