Science of Love - Cupid's Chemistry

Love; what is it, where does it come from and why?

What is Love ?

The Oxford English dictionary describes love as: an intense feeling

of deep fondness or affection for a person or thing and to fall

in love as: to develop a great love for. This may well be a basic

description of what love feels like, but why do we love, what is

passion, and why is intense desire between two people sometimes

called 'chemistry'?

There are, in fact, three distinct stages of love; each with their

own characteristic emotional profile and scientific explanation.

First is lust. Lust is driven by our sex hormones testosterone

and oestrogen. These hormones are what get us 'out on the pull'.

After lust comes attraction. This is the love-struck phase; the

time when we lose our appetite, can't sleep, and can't concentrate.

This is what we know as falling in love.

When we fall in love, our palms sweat, we can stutter and become

breathless, we can't think clearly and it feels like we have butterflies

in our stomachs. This is all due to surging brain chemicals called

monoamines. They are called dopamine, norepinephrine and serotonin.

Norepinephrine and serotonin excite us, while dopamine makes us

feel happy. These love chemicals are controlled by a substance which

is also found in chocolate and in strawberries, called PEA or phenylethylamine

and it is PEA which controls the transition from lust to love. Similar

in structure to amphetamine, PEA too gives us that excitement we

crave. Indeed, some people become veritable love junkies. They need

a constant love high and go through life in a series of short relationships

which crumble when the initial chemical rush wanes. The love junky

has another problem too. We naturally build up a tolerance to these

chemicals eventually, so it takes more and more to produce that

much sought after high. Love junkies, if they stay married, are

likely to seek frequent affairs to fuel their need for the chemical

love high.

The Chemical Bond

The third stage of love is attachment - staying together. Attachment

takes over from the attraction stage and is the bond which keeps

couples together. After all, we couldn't possibly stay in the attraction

stage for ever - we would never get any work done for day dreaming.

Two different hormones are important during this phase of love.

They are oxytocin and vasopressin.

Oxytocin (the cuddling chemical) not only increases the bond between

lovers, but is also one of the chemicals responsible for contractions

during childbirth, milk expression when breastfeeding and is released

by both sexes during orgasm. The theory goes therefore, that the

more sex a couple have, the greater the bond between them. Nice

touch Mother Nature.

Vasopressin is the monogamy chemical. Only about three percent

of mammals are monogamous; mating and bonding with one partner for

life. Unfortunately, humans are not one of these naturally monogamous

animals. The prairie vole is however and it is this furry friend

which is responsible for our knowledge about vasopressin.

By isolating male voles before and after mating, scientists found

that life-long mating could be linked to the action of vasopressin.

Before mating, the vole is friendly to male and female voles alike.

Within 24 hours after mating, the male vole is hooked for life and

defends his partner jealously. The post-coital production of vasopressin

is responsible for this amorous behaviour. These little animals

also indulge in far more sex than is actually necessary to reproduce

and it was considered that the post-coital production of vasopressin

(and oxytocin) was responsible for their strong partnership bonds.

When given a compound to suppress the effect of vasopressin, the

prairie voles lose their devotion to each other and the males fail

to protect their ladies from the threat of other males. Perhaps,

therefore, we could learn something from the prairie vole. Drop

of vasopressin anybody?

Endorphins are also involved in the longevity of love. Endorphins

have the same pain-killing and pleasure-delivering properties as

their cousin, morphine, without the risk of overdose.

Choosing a Partner

Now, when it comes to choosing a partner, are we at the mercy of

our subconscious or do we make a more conscious decision?

It is to our advantage to choose a partner with the best possible

genes as these genes will be passed on to our children and ensure

they are healthy. Therefore, we naturally seek out somebody with

an immune system different to our own. Additionally, it is important

to find a mate with whose genes are also similar enough to our own

to confer a tried and tested immune system. Is this the reason we

fancy those who remind us of our parents perhaps? When we are attracted

to another person, it could be because we subconsciously like their

genes.

How do we do this? We seek and sniff out Mr Right!

Imagine an invisible overwhelming force which overpowers reason

and invites passion. A force which dictates where Cupid's arrow

will land. Cupid's chemistry. That's the power of pheromones. Pheromones

are 'smellprints', supposedly as unique as our fingerprints. Smell

is the most primitive of human senses, and pheromones, present in

underarm perspiration, are detected by a small organ composed of

a few small pits a few centimetres up the nose. The emotional reaction

they provoke can, quite literally, be a 'turn on'!

Therefore, next time you find chemistry with another person, you

really have!

- February 2006

(Claire McLoughlin is from the press and publications department of the Royal Society of Chemistry)