The Science Behind Kissing (Why Do We Kiss)

We all remember that first kiss.

A person who made us feel special, the butterflies in our stomach as we lean forward to touch

lips and share a moment of intimacy.

This human ritual of touching lips and kissing has been around for generations, and it has

different meanings depending on the culture and context.

Everything from love, passion, romance, to sexual attraction.

But we also share 80 million bacteria when we kiss each other!

Wow, that’s quite an exchange for a moment of passion.

So what’s it all about?

That’s what we’ll be looking at in this episode of The Infographics Show: Why Do People


It may seem that kissing is something that everyone does, but analysis suggests that

less than half of all cultures actually do it and kissing is also very rare in the animal


So what really motivates us to kiss and if it was really meant to be everyday behavior,

why don’t all humans and some animals do it?

According to the BBC, a study of kissing preferences, which looked at 168 cultures from around the

world, only 46% of those cultures kiss for romantic or loving reasons.

Previous estimates had put the figure at 90%.

So romantic lip slapping looks to be less common than we might have imagined.

And why the lips anyway?

I mean we could show romantic passion by rubbing foreheads, by giving high fives, or by turning

back-to-back and bumping butts.

There are endless different ways we could touch bodies to show a romantic gesture.

You may have heard the term Eskimo kiss, also called a nose kiss or nose rub.

This is where you press the tip of your nose against another's nose as a friendly greeting.

Eskimos do it, but so do other cultures.

Maybe the real reason people kiss is simply because it just feels good.

That seems a bit of a lame explanation as most human behavior dates back to some ancestral


So far scientists haven't conclusively explained how kissing originated, but they've come up

with a few theories and according to online journal Live Science, it seems to be widely

accepted that humans kiss each other as it helps to identify the right mating partner.

When our faces are close together, we exchange pheromones; biological information about whether

or not two people will be good together and produce children.

As an example women subconsciously prefer the scent of men whose genes for certain immune

system proteins are different from their own, because this kind of match could yield offspring

with stronger immune systems, and better chances for survival.

There have been a number of studies on this and the first study to indicate that chemical

signals play a role in attraction was conducted by Claud Wedekind more than 20 years ago.

Wedekind and his team collected DNA samples from 49 female students and 44 male students.

He asked the men to wear cotton T-shirts two nights in a row, to keep the shirt in a plastic

bag, to use perfume-free detergents and soaps and to avoid smelly rooms, smell-producing

foods as well as activities, like smoking and sex that can create odors.

As for the women they were given a nasal spray to use for two weeks before the test to protect

their nasal membranes from becoming infected.

And they were even each given a copy of the Patrick Suskind novel ''Perfume'' to make

them more conscious of odors.

Women then sniffed the worn t-shirts of men to get a sense of which smelt the best.

To test the results, researchers compared the DNA of the women and the men to see if

a pattern had evolved.

They found that women didn’t just choose their favorite scent randomly.

They preferred the scent of man whose major histo-compatibility complex or MHC, which

is a series of genes involved in our immune system, was different from their own.

When a couple who have different MHC produce a child, there is a better chance of the newborn

being strong and healthy.

So perhaps that bad first kiss may be more than nerves and could instead be a woman picking

up on the true strength of the scent.

Ok, so maybe there’s more to kissing than just the simple pleasure of the act.

What else is there to know about kissing?

We found some interesting random facts when we stumbled across a Cosmopolitan article

from 2017.

Here are a few you may not have known:


Women more likely to orgasm when there’s some kissing involved – According to Cosmopolitan,

a study also showed that those who indulged in more foreplay, such as deep kissing and

more affectionate post-sex kissing, were found to be more sexually fulfilled.


Kissing doubles the speed of your metabolism – Don’t get too excited, it’s not like

30 minutes on a treadmill, but kissing does double the speed of your metabolism.

A good smooch can burn two calories a minute and if you get really heated up you can burn

up to six calories per minute.

So it’s good news, though you may need to kiss for 24 hours to have any recognizable



It can strengthen your immune system – We started out this show talking about the 80

million or so bacteria that are transferred when kissing.

That sounds pretty yucky, and you might end up with a cold you never bargained for, but

it also helps to boost your immune system, as when your body is introduced to new bacteria,

it has a better chance of fighting off infection in future.


Sealed with a kiss – In medieval times, before reading and writing was common practice,

people would sign contracts with an X before kissing the X they had just written, as a

way of to sealing the contract.

And that is why today people write an X to mean a kiss.


And last but not least, kissing makes you happy - According to science, a decent kiss

gets the body going and releases plenty of mood boosting chemicals such as dopamine,

oxytocin, and serotonin, which stimulate the pleasure centers within our brain, providing

us with a natural high.

So whether it’s a peck on the cheek, a more romantic lip connection, or the ‘all in’

French kiss, better known as a good old snog, it seems that kissing is a human pastime that

won’t be going anywhere fast.

How was your first kiss and do you even remember it?

Let us know by commenting below.

Also be sure to check out our other video, How Is KISSING Different Around The World?

Thanks for tuning in to this episode of The Infographics Show and remember to like, share

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