Our breathing can deepen and become irregular.
Our heart starts to race, our pupils dilate
which might be one of the reasons so many people
close their eyes during a kiss.
There are three sensations
that one should really recognise when they're kissing.
First of all there's the wonderful feeling of touch
because our lips are extremely sensitive,
we have more nerve neurons on the end of our lips
than any other place in our body,
except some areas in our genitalia.
And then of course also there's taste.
Each individual has a unique taste to them
and some people are much better at recognising taste than others
and then of course there's also smell.
Ovid in some of his poems talked about kisses smelling
like ripening apples in a chest.
There's a lot of theories as to why we kiss
but some of it may have to do with our earliest experiences
on planet Earth.
When we're infants, through being kissed by parents
and also through nursing, through a lot of lip stimulation
that becomes associated through neural pathways in our brain
with these very, very positive emotions.
And so we're building these neural pathways
that attribute kissing and lip stimulation with love and security
and all of these wonderful things
that later in life when we want to express ourselves that way,
we probably do so using our mouth.
While we can't zip ourselves back in time
and kind of discover when and where and how the first kiss
took place among humans,
what we do know is that other species
are very attracted to the rosy bottoms of females
when they're at peak fertility, when they're in estrus.
There are some anthropologists that think that the lips
are what's called 'the genital echo' so they mimic the female genitals
in shape, composition, colour and texture,
and they serve as reliable indicator
of when a woman might be ready to mate.
Desmond Morris, a British zoologist,
he's actually done some research on lipstick,
showing different men images of women's faces
asking who the most attractive are?
And over and over and over men are consistently choosing the women
who are expressing the rosiest most coloured lips in these studies.
So there's something that does draw our attention to the mouth
and the colour red is a colour that many species
use to exhibit this sexual signal.
The earliest evidence that we find of any kind of kissing
is about 2,500 maybe 3,500 years ago, in some of the early Vedic texts
that come from India.
It turns out that the area right below your eyes has sebaceous glands
that produce a unique smell for each individual.
So these ancient Indians in northern India were sniffing each other
and of course if they ran their noses across the cheeks of each other
and then across the nose to the other side of the cheek,
I think that occasionally some of them slipped
and may have ended up on the lips
and because the lips are so sensitive,
they may have found that that was much more pleasurable
than just sniffing each other.
The Romans can be looked upon really as
probably the first great kissing culture.
They had different kinds of kissing.
The savium was what we might call a French kiss.
Based on the word saliva which we still use today
and of course they enjoyed practicing this all the time.
There's places where people just thought kissing was disgusting
which might not be that surprising when you consider that
for the most part, people weren’t brushing their teeth and flossing,
using mouthwash and all these things we do today,
where it would probably be a lot less appetising not that long ago.
However, it's something that even where we didn’t do that
we were sniffing, we were patting,
we were licking and sucking and nibbling
and doing things all about each other's bodies to connect
and that connection is ultimately important for keeping us together,
for keeping our bonds strong,
for raising all of the different hormones and neurotransmitters
in our bodies that make us maintain our important relationships.
And kissing is a big part of that.