Romantic kissing is done the world over. The vast majority of human beings kiss. In fact, about 90% of the world’s population kisses in a romantic way.

Researchers at Layfayette College in Pennsylvania studied kissing and it’s impact on romantic relationships. We have often heard that someone being a terrible kisser is often a deal-breaker and the relationship often falters and ends if no improvement is seen. Yes, it seems – kissing is that important! And it’s not just a social or societal thing – it’s scientific.

Kissing releases the hormones oxytocin and cortisol – the former relates to social bonding while the latter connects to stress. These hormones in men and women in the study reacted differently. Women are usually attracted to men with a different immune system to theirs and scents released in kissing can allow a woman to unconsciously detect the man’s immune system.

Also discovered? Women want kissing before a sexual encounter more than men. Another study showed that bad kissing can end a relationship 50% of the time.

The science of kissing even has a name: philematology. Research on the subject was presented at the annual meeting of the American Association for the Advancement of Science in Chicago on Friday.

“Kissing is not just kissing. It is a major escalation or de-escalation point in a powerful process of mate choice,” said Helen Fisher, professor at Rutgers University and author of the book “Why Him, Why Her: Finding Real Love by Understanding Your Personality Type.”