Mostly unique to humans, the romantic kiss may help men and women assess and then retain partners, for either casual encounters or the long-term bond.
The kiss, although seen to an extent in chimpanzees and bonobos, appears as a human courtship and mating-retention behavior across world cultures, as universal as language and facial expressions. In a survey of more than 900 people ages 18-63, men and women making choosier mating selections tended to place greater value on the kiss, lending credence to the theory that kissing helps assess the genetic quality of potential mates.
Women as a group tended to rate the kiss as higher in importance than others, perhaps given the biological resources and time spent following a single mating choice — nine-and-a-half months of gestation followed by several years of breastfeeding. Similarly, men and women who rated themselves higher in physical attractiveness also placed greater importance on the kiss, for either casual or longer term relationships, perhaps reflecting a wider array of options and the relative luxury of choice.
Investigators at Oxford University who conducted the study surmised that although the kiss may increase physiological arousal, survey data appears to support mating selection and retention goals as the primary drivers of the behavioral trait.
“Kissing in human sexual relationships is incredibly prevalent in various forms across just about every society and culture,” Rafael Wlodarski, a doctoral student who helped conduct the research, told reporters. “Kissing is seen in our closest primate relatives, chimps and bonobos, but it is much less intense and less commonly used.”
Leading the investigation, Robin Dunbar sought to test the three main theories explaining the romantic kiss, reporting their findings dually this month in the journals Human Nature and Archives of Sexual Behavior. “Mate choice and courtship in humans is complex,” she said. “It involves a series of periods of assessments where people ask themselves, ‘Shall I carry on deeper into this relationship?'"
Initially, attraction between two individuals may be based upon facial, bodily, and social cues, Dunbar said. “Then assessments become more and more intimate as we go deeper into the courtship stages, and this is where kissing comes in.”
Through time and space and across cultures, every man and every woman might at one point relate to romantic travails described in late 18th century English literature, according to Wlodarski. “In choosing partners, we have to deal with the ‘Jane Austen problem’: How long do you wait for Mr. Darcy to come along when you can't wait forever and there may be lots of you waiting just for him? At what point do you have to compromise for the curate?”
In the classic novel, the protagonist “realizes that people are extremely good at assessing where they are in the ‘mating market’ and pitch their demands accordingly,” Wlodarski said. “It depends what kind of poker hand you've been dealt. If you have a strong bidding hand, you can afford to be much more demanding and choosy when it comes to prospective mates.”
Among other findings, the researchers say women place even greater importance on the kiss during higher points of fertility in their monthly cycle, when they might most need to exercise discretion, to play their hand or to fold.
Source: Wlodarski, Rafael, Dunbar, Robin I. M., Menstrual Cycle Effects On Attitudes Toward Romantic Kissing. Human Nature. 2013.
Wlodarski, Rafael, Dunbar, Robin I. M., Examining The Possible Functions Of Kissing In Romantic Relationships. Archives Of Sexual Behavior. 2013.