This Valentine’s Day, as lovers everywhere exchange boxes of chocolates, bouquets of roses and sweet nothings, there’s actually a lot more going on under the surface, say Kansas University researchers.

Adrianne Kunkel, associate professor of communication studies, researches the dynamics of romantic relationships. She said the holiday, which is Sunday, can be an opportunity for many.

“Valentine’s Day offers an opportunity to get involved in a relationship, and it also offers an opportunity for somebody who’s already involved in a relationship to take it to the next level,” she said.

A partner may be motivated by a desire not to spoil the celebration, and might be more willing to accept the offer, she said.

Those opportunities can be a little tricky, though, if navigated improperly by either person in a romantic partnership.

“I think the most important thing is for people to be honest, straightforward and direct, and not try to cover their intentions with red and pink frosting,” she said.

And, after all, humans are hard-wired to want these kinds of relationships, said Omri Gillath, assistant professor of psychology.

Hugging, kissing and other more amorous pursuits trigger the release of a chemical called oxytocin into the bloodstream, he said.

The chemical acts as a kind of “glue,” making two people feel good when they engage in this kind of activity, he said. Another chemical, dopamine, is released when humans take risks, like skydiving, or beginning new relationships, he said.

And, he said, while it may not sound romantic, there’s a scientific reason the body is producing these chemicals when we seek out relationships.

“At the end of the day, from an evolutionary perspective, the purpose of all that is to reproduce,” Gillath said.