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
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
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
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
- February 2006
(Claire McLoughlin is from the press and publications department of the Royal Society of Chemistry)