We spend two weeks of our lives kissing. Whether to show love, greet someone, exhibit affection or express respect, everyone does it. The thing is: no one knows exactly why we started doing it. Not surprisingly, Romans were the ones responsible for spreading the act of kissing across Europe and parts of North Africa. They basically had three types of kiss: osculum referring to a kiss on the cheek or hand; basium when it was a kiss on the lips, often between relatives; and suavium when it was a love kiss.
Despite the fact that more than 90% of human cultures are familiar with kissing, scientists still don’t know why we kiss. Some think it’s a learned behaviour, while others believe it’s an instinct we were all born with. Bonobo apes actually do kiss, which makes the instinct hypothesis a little bit more robust. Interestingly, a few cultures thought that the soul exists in the breath of a person, so kissing was an effort to bring the souls closer to each other. One very popular hypothesis says that kissing had its origins in kiss-feeding – the act of transferring chewed food from parent to children in order to feed them -, a behaviour seen in various mammals. Needless is to say that french kissing has some striking similarities with kiss-feeding.
Kissing someone on the lips can potentially transmit some diseases though, such as herpes and mononucleosis (also called ‘kissing disease’). Recently, researchers proposed that kissing may be an evolutionary adaptation to protect pregnant women against fetal malformations caused cytomegalovirus. Females can only gain this benefit if they also avoid becoming infected by other males, which also constitutes an evolutionary pressure towards monogamy.
But, fortunately, the benefits don’t stop there. A research paper published in the Western Journal of Communication found that the experimental group of people they instructed to increase the frequency of romantic kissing in their relationships for only 6 weeks experienced lower levels of stress and cholesterol and higher satisfaction with their relationships compared to the control group. Another study also found out that kissing may be linked to the decrease of IgE, the immunoglobulin our body produces in the allergic reactions. Does that mean you should start kissing your loved one more often to treat your allergies? Probably not, but it wouldn’t hurt you!