Men like to push to make kisses sloppier, while women want to keep them long, suggest a new study.
Also, a kiss shared between a man and a woman seems more like a clash of spirits than a meeting of souls.
"Women tend to use kissing to create a bond with their partners, and to assess them as potential mates. Meanwhile, men use kissing as a means to an end," said Susan Hughes, a psychologist at Albright College in Pennsylvania, told Life’s Little Mysteries.
And that end is sex.
"Males are kissing primarily to increase arousal for their partner," she said.
Hughes and her colleagues researchers probed the kissing preferences and opinions of more than 1,000 males and females in their sexual prime - college undergraduates - who were asked to mark their answers to a series of detailed kissing questions on a 5-point scale.
The results showed that both men and women consider kissing an important and highly intimate interaction. Both sexes use kissing to gauge the relationship compatibility of themselves and their partners.
Furthermore, both may become more or less attracted to their partners based solely on their experience kissing them, a result that lends support to the theory that pheromones and other important biochemical signals get exchanged when people kiss.
But the similarities end there. While women usually consider a bad kiss to be a deal-breaker, men reported that they would more than likely still have sex with a woman even if she were a bad kisser.
In fact, the data showed that males feel much more strongly that kissing should lead to sex than females do.
"Whereas females felt there was a greater likelihood that kissing should lead to sex with a long-term partner than a short-term partner, males felt that in either instance, kissing should lead to sex," wrote the researchers.
Men also like significantly wetter kisses. The gender divide becomes drastic when the kissing involves short-term partners, who presumably hold primarily sexual rather than romantic appeal. In the short-term, men like kisses to be wet, while women do not.
Psychologists hypothesize that males "perceive a greater wetness or salivary exchange during kissing as an index of the female’s sexual arousal/receptivity, similar to the act of sexual intercourse," wrote Hughes.
Follow-up research conducted by Helen Fisher, an anthropologist at Rutgers University, in 2009 even found that men pass testosterone to women via their saliva, which may momentarily increase the women’s sex drive.