Reference my previous message on the �Puppy Love� thread, Annette has
reminded me that the London Times is not available online outside the UK,
so I�m hoping I�ll be allowed a special dispensation to post a fourth
message today!
London Times, 22 March 2004
Double dating: What twins can tell us about falling in love
By Helen Rumbelow
When you meet that special person your heart flutters and the violins
begin to play � but scientists believe there is more to it than that. They
are experimenting with sets of twins to try to prove that our bodies
"scan" potential partners for the perfect genetic match.
ONE HUNDRED AND EIGHTY-SIX years ago Arthur Schopenhauer was at his desk
in Dresden, formulating his thoughts on love � or rather, debunking the
whole silly idea. Instead of romance, we are all engaged in a ruthless
quest for a mate who will compensate for our flaws and so create the
perfect child, the philosopher wrote. A suitor, unwittingly, �loves what
he lacks�. �What he regards as beautiful in another individual are those
perfections which he lacks, those traits opposite of his own, guided by
what�s best for the species.�
Schopenhauer, who was neither lucky in love nor particularly happy in
life, would have been cheered by the goings-on at St Thomas� Hospital in
South London on a spring Saturday. Here, in the wood-panelled Governor�s
Hall, was a scene of frenetic and surreal activity. More than 100 sets of
twins were bustling about in small groups, conducting odd experiments. In
one corner a pair of young black women, exact mirrors of each other down
to the large hoop earrings and tight jeans, were smelling a cotton pad
stinking of body odour. In another, on a row of chairs, sat a line of
doppelg�ngers, their identical heads staring at a slide projector showing
photographs of faces which they rated for fanciability on the clipboard on
their laps. In a booth one man was repeating the word �cat� into a
microphone as his twin silently mouthed the words under his breath.
What was going on inside this mad scientist�s lair? Those inclined to
soppiness may want to look away now, for this extraordinary British
experiment is on the brink of proving Schopenhauer�s thesis � albeit a
more sophisticated version based on our genes. We are often told that we
desire people who share our background, interests, and even looks. But
this study is the first that sets out to prove that we are looking for a
mate with a genetic make-up that complements rather than copies our own.
When you think of the moments when you began to fall in love � the
glimpse of your beloved�s face, the smell of their pyjamas, the sound of
their voice � they may have been the exact moments that your body was
busily comparing their DNA to your own. Love at first sight could describe
the point when your mind, subconsciously, decides that your mate�s genetic
code is different enough to make a robust baby if you got it together.
The genetics of human attraction are new and uncharted waters, but could
go some way to unlocking the great mysteries of the human heart. Marion
Petrie, a researcher in evolutionary psychology at the University of
Newcastle, stands in the centre of the hubbub. Inside this hall, which has
been dubbed �Twinland� for the day, you can hear a lot of stories about
twins sharing boyfriends or girlfriends (no, not at the same time). When
the results are published at the end of the year, this study could explain
why.
Take Alice Cudlip and Lucy Birkbeck: blonde, 36, and identical. Alice is
married and Lucy has a long-term boyfriend, but before their personal
lives became defined there was a certain amount of give and take. �We have
both gone out with the same man,� Lucy confesses. �It�s embarrassing to
talk about because it sounds weirder than it is.�
What could have drawn both Lucy and Alice to the same fortunate man? The
theory is not at all romantic: human desire may be mixed up with a process
called �outbreeding� (the opposite of inbreeding). For obvious reasons,
suitors who look weak or sickly have never been a big turn-on. But then
it�s believed that a more subtle vetting of a mate takes place, designed
to ensure that any offspring have the best immune systems their parents
can bestow on them.
This effect was first noticed in mice in the mid-1970s, when it was
proved that a female mouse could discern information about a male mouse�s
immune system genes by smell. She avoided mating with a mouse that had
similar immune system genes to her own.
In humans these genes are called human leukocyte antigens (HLAs), which
means they govern the immune system. If you were, say, receiving a heart
transplant, these genes would have to be matched almost exactly with your
donor. When you fall in love, the effect may be entirely the reverse.
The broader the spectrum of immune system genes you have, the more
protected you are against disease. �It gives you a bigger armoury,� Petrie
says. This is why it is so important that the set of HLA genes a child
inherits from its mother are as different as possible from the ones it
gets from its father. And it�s an added bonus if your mate not only has
different HLA genes from yours, but his genes are mixed up already.
We know that people can detect HLA genes by smell, with tests showing
that women prefer the body odour of men with more mixed HLA genes. But you
may be giving off signals about the strength of your immune system in all
sorts of other, unwitting ways that you can�t disguise with deodorant.
Petrie and her fellow researcher, Craig Roberts, conducted an experiment
on three dozen Newcastle women. They took photographs of a random group of
men and tested their blood to assess whether they had particularly mixed
HLA genes. Then they asked the women to rate the men�s photos for
attractiveness. Nearly all the women picked out the men with the most
robust immune system genes.
Now Petrie and her team wanted to be the first to test whether the body
was able to discern not just a mate with a good immune system, but whether
they would make a good match for your own. To do this, they enlisted the
help of the Twin Research Unit at St Thomas�. This centre draws on a large
database of Britain's twins to figure out the difference between nature
(your genes) and nurture (your upbringing or environment) by comparing
identical twins, who are genetic clones, with non-identical twins. Petrie
knew that if identical twins were more likely to find the same man
attractive than non-identical twins, then their choices were being
influenced by their DNA.
Excitement hung heavy in the air as all the twins were assembled. (They
had been told not to wash or wear perfume or deodorant.) Their blood was
taken to measure their HLA genes, and then the Newcastle team put them
through all sorts of tests to see how people use their five senses to
detect HLA genes. So participants did not just have to smell jars
containing pads that had been worn by Newcastle men (�Geordie armpits� as
they became known by the twins), and rate the facial attractiveness of
large numbers of men and women, but also to say and listen to vowel
sounds. As far-fetched as it seems, the very tone of your voice could be
giving away clues to your mate-ability. �Your vocal chords could be
affected by disease � we just don�t know,� Petrie says.
As the male and female twins queued for tests and chatted about
twin-liness, their bodies may have been exchanging all kinds of flirty
information about their immune system � HLA business cards, as it were.
Not that they were all available. You might think that those in loving
relationships would find this theory of how they�d found their mates a
little repellent. �I can�t believe that�s the sum of it � sniffing
someone�s armpit,� Alice Cudlip remarked. �You always want to feel you
have met someone special,� her sister Lucy adds more diplomatically. �But
it�s complicated � because you wouldn�t be aware of any of this stuff
going on.�
Quite. After all, no one thinks, �What beautifully different immune
system genes we have, I�ll go for him�. You just think, �Wow!� But perhaps
it was the recognition of an HLA match made in heaven that was behind the
coup de foudre experienced by Jo Smith, who is 33, and a non-identical
twin. She describes the first glimpse of her fianc�, Paul, thus: �He
walked into the office where I work and it was love at first sight. We
both looked at each other and I felt we sort of knew . . . I do believe in
the idea of soulmates.� Soulmates or genetic mates?
With research in its infancy, we don�t know how powerful a role biology
plays in people�s love matches. Some studies on the Hutterite religious
community in America show that it becomes more important the more limited
the choice. But, as Petrie points out: �We know people do get it wrong.
One of the problems of mating with someone too genetically similar to
yourself is infertility.� Studies of infertile couples show a higher than
average degree of HLA similarity. As women who take the contraceptive pill
seem to have a dampened ability to choose men with diverse HLA, this could
be a modern predicament.
But left to its own sweet way, your body is making hard-headed
calculations about who to desire based on genetic coding, then fooling
your consciousness into hearing the violins play every time they walk in
the room.
The notion that biology is romantic destiny might not be quite as alien
to identical twins as to the rest of us: if you are one of a pair you
struggle with issues of genes and identity all your life. How many
non-twins could imagine, for example, the process of natural selection by
which Annabel Gersch, 45, acquired her husband, leaving her identical twin
sister Pauline in the dust? �I met my husband on a double date with
Pauline,� Annabel relates. �He met us, he saw we were both twins, and he
said, �I can�t decide, I�m taking you both out�.� One might think this
would have been the end of romance with either woman. Not a bit of it. �He
turned up at the house � we lived together at the time � and he didn�t
even know our names, so he had a bouquet for both of us, one addressed to
�one half� the other to �the other half�. We came home from dinner and I
said, �I �m having him,� and that was it. I told him the next morning that
we had decided.�
By the end of the day, as the twins sit exhausted and smelly, I have
heard several similar stories. Take Anita Hair, 45, a librarian from
Essex, and her identical twin sister Julia Rosenberg (both dressed in
black tops, both have two children � such details are commonplace in
Twinland).
Anita even acquired her husband, Richard, from her identical twin sister,
who went out with him before she did (as we speak, she is in the process
of entertaining twins Shaun and Simon Bishop, 37, from Leicester).
According to the principles of the day, they could have shared their
attraction for Richard because they both had fantastic � and identical �
HLA compatibility with him. Does the thought take the edge off their
romance?
�Who you love comes from so deep inside,� Anita says. �You always think
it�s in your heart � but to hear it�s DNA, to hear it�s that deep, is odd.
Perhaps we shouldn�t know too much about it, perhaps it�s meant to be
mysterious,� she says.
In another corner of the room, James and Richard Young, 23, from
Hertfordshire, are talking girlfriends with their older brothers, Garry
and Adrian Redrup, 33, another twin set in the same family. �Of course we
all like the same thing in a woman, we all like big boobs,� Garry says.
But James thinks his girlfriend would be disturbed to hear about the
genetics of attraction. �She likes to think we were meant to be, that
we�re soulmates,� he says.
Does James believe in soulmates? There is a long pause, and then an
answer which would make Schopenhauer proud.
�Erm . . . �
WHEN ROMANCE IS ON THE BRAIN
Love is the drug: in 2000 Andreas Bartels and Semir Zeki, of University
College London, located the areas of the brain activated by romantic love.
Students claiming to be madly in love underwent brain scans. It was found
that a relatively small area of the human brain is active in love � the
same part responsible for the euphoria felt after taking drugs.
Love is blind: more than a decade ago an American psychologist, Professor
David Lykken, discovered �the Titania Syndrome�. After long-term work with
1,000 pairs of identical twins, Lykken concluded that at certain times in
our lives we are in such a state of readiness that we will fall for almost
the first person who appears, and will be blind to their faults, just as
Titania was to Bottom�s.
Love maps: Dr John Money, a leading sexologist based at Johns Hopkins
University, coined the term to describe the mental blueprint each of us
has for what is sexually exciting and erotic. Acquired through heredity
and early-life experience, the �love map� is a kind of checklist of
attributes that will trigger attraction in us.
Vole play: We may have something in common with prairie voles: preliminary
studies by psychiatrist Kathleen Light at the University of North Carolina
have found that after couples hold hands, hug or watch romantic movies,
levels of the hormone oxytocin rise. Prairie voles, whose brains have
receptors for oxytocin, also bond after sex, and remain mated for life.
Allen Esterson
Former lecturer, Science Department
Southwark College, London
[EMAIL PROTECTED]
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