These are the main findings from the scientific study of kissing

Love is in the air as Valentine’s Day fast approaches and Dr Naomi Lavelle is here to tell us all about the science behind kissing.
These are the main findings from the scientific study of kissing

With romance in the air this week it is a good time to look at the act of kissing, platonic or romantic, why do we do it at all and has science got anything to say on the matter? It turns out it has… there is even a name for the scientific study of kissing… it is called Philematology and here are some of its findings!

The origins and evolution of the kiss

Why do we kiss at all? If you think about it, it is a bit of an odd thing to do, so why did we start and why are we still doing it? There are a couple of theories on this.

The first is that it might have evolved from something called kiss feeding, when a mother chews food and passes it, mouth to mouth, to her baby. This may have become known as a sign of affection and developed into the types of kissing we know today.

Another theory is that we do it because it feels good and we are hot-wired to it from birth. The lips are one of the most sensitive parts of the body. As babies we use lip pressure to stimulate the suckling process.

Be it breast or bottle, we use the orbicularis oris muscle when sucking as infants. Is it a coincidence that these are the same muscles we use when we pucker up for a kiss? Is kissing a by-product of a nerve memory we laid down as infants?

Both activities tend to cause the release of oxytocin into our bodies, a feel good hormone, often called the cuddle chemical, that is part of the bonding process.

What other animals do it

Kissing does not seem to be prevalent in the animal kingdom, except among our closest relatives — chimpanzees and bonobos. With chimps, kissing seems to be more of the ‘kiss and make up’ kind, more platonic and social. Bonobos appear to use a more ‘romantic’ kiss just like we do.

What cultures don’t

Although kissing is a fairly human thing, we’d be wrong to assume that everyone does it. It is estimated that about 90% of humans kiss, but, if we take away platonic kissing and look just at the romantic kiss, a recent study (2015) reported that only 46% of cultures actually use it.

The study associated romantic kissing with more socially complex cultures. Many hunter-gatherer groups studied did not. Others, such as the Inuit culture, may express affection differently, such as the rubbing of noses.

What can we tell from a kiss?

So why do we kiss at all? One reason might be to check out a potential mate. Kissing allows us to get close enough to smell someone, are we unconsciously checking out their pheromones?

Can we tell how compatible we are just by their smell? A 1995 study showed that women were more attracted to the smell of T-shirts worn by men that had different genes linked to our immune system make-up (the Major histocompatibility complex (MHC) genes).

It would make sense to pick a mate in this way, as children from such as couple would get a mix of these immune system genes, giving them a healthy advantage in life. If this is true it certainly gives strength to the old saying that opposites attract.

  • Naomi is a science communicator and mother to three inquisitive children. She can be found at
  • If your child has a question email

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