A kiss is more than just a kiss – it acts as a screening tool to help us find the right partner, new research suggests.
When two people kiss, they get very close, allowing each individual to assess the other through taste or smell. The signals kissing provides may provide biological cues for compatibility, genetic fitness or general health, scientists believe.
Researchers investigated the smooching truth by conducting an online survey in which more than 900 adults answered questions about the role of kissing.
"Kissing in human sexual relationships is incredibly prevalent in various forms across just about every society and culture," said psychologist Rafael Wlodarski, from Oxford University, who led the study.
"And we are still not exactly sure why it is so widespread or what purpose it serves."
The survey responses, reported in the journals 'Archives of Sexual Behaviour' and 'Human Nature', showed that women rated kissing as generally more important in relationships than men.
Men and women who rated themselves as being attractive, or who tended to have more short-term relationships, also saw kissing as more important.
Both men and women who are more attractive, or have many casual partners, are also known to be extra picky when looking for a long-term potential mate.
Since, according to the survey, both groups also place a high value on kissing, it suggests that kissing may help in mate assessment.
Co-author Professor Robin Dunbar, from the Department of Experimental Psychology at Oxford University, said: "Mate choice and courtship in humans is complex. It involves a series of periods of assessments where people ask themselves, 'shall I carry on deeper into this relationship?'.
"Initial attraction may include facial, body and social cues. Then assessments become more and more intimate as we go deeper into the courtship stages, and this is where kissing comes in."