快猫短视频

EVERYONE knows the adage that when it comes to eyeing up prospective mates,
opposites attract. Well, not in David Perrett鈥檚 lab they don鈥檛. In the quiet
confines of the psychology department at the University of St Andrews in
Scotland, like attracts like with unerring regularity. And while there鈥檚 no
actual sex involved鈥攋ust a lot of students gazing into the faces of
hypothetical mates on computer screens鈥攖he results have been creating
quite a stir.

Perrett is a cognitive psychologist and well-known manipulator of human faces
(British readers may recall his famous stepwise, digital morphing of Margaret
Thatcher into John Major). And for more than a decade he and his team have been
sitting people, usually students, in front of computers, showing them a stream
of faces and asking them simple but telling questions like, who do you fancy
most?

Their attempts to pin down the essence of facial attractiveness have been
reported by so many newspapers in recent years that most of the findings have a
familiar ring. Like other psychologists, for instance, Perrett and his team find
that being average is a good way to attract. Blend lots of faces together and
you get a bland yet curiously attractive composite which people rate more highly
than even the most appealing of the individual faces.

Also like psychologists elsewhere, Perrett and his team find that they can
get even higher ratings by exaggerating certain features of these fanciable,
average faces. Make the man鈥檚 brow and chin more imposing and the jaw larger,
and in a trice he becomes as alluring as a young Brando. Make the woman鈥檚 face a
tad flatter and longer, her chin smaller and cheekbones more prominent (think
Audrey Hepburn) and she too beats the average hands down. All of which suggests
our beauty detectors are finely calibrated to respond to some sort of 鈥渋deal鈥�
face.

But here鈥檚 the rub. When Perrett and his colleagues photograph the face of
the person doing the rating, subtly change its sex using their clever morphing
program, and then flash that image up on the screen, people really go for this
sex-changed version of their own face. They never recognise it as a feminised or
masculinised form of themselves. There鈥檚 just something about it that appeals.
And now the scientists think they know what that something is. We are attracted
to such faces, it seems, not because they unconsciously remind us of ourselves,
but because they remind us of our mum or dad.

In other words, there may be a grain of truth in the Freudian idea that we
learn what to look for in a partner by gazing into the faces of our parents
during our impressionable years. And if it sounds like just another quirky
psychology theory, think again. The evidence to date may not be exactly
cast-iron, but Perrett and his team believe they have stumbled on something that
could be central to the way we play the mating game. If so, it鈥檚 a force that
has shaped human evolution. It may even help explain why racial characteristics
vary more than adaptation to different environments alone would suggest鈥攁n
idea that Perrett and his team are now testing.

Many readers will already be reaching for their pens. Yet the basic
observation that people tend to choose mates who are boringly similar to
themselves is actually nothing new. Psychologists have known for decades that
total strangers can pair up married couples from photographs of the individuals
with eerie accuracy. What wasn鈥檛 so clear in the past was just how strong and
discriminating the attraction between lookalikes is. It may not always trump the
desire for a perfect jaw or chin, but, according to Perrett鈥檚 research, it鈥檚 a
force to be reckoned with. And it鈥檚 a force, too, whose evolutionary purpose
remains something of a mystery. Like may well attract like. But to what end?

The fact that there are ideal faces we all rate highly is easier to explain.
In recent years, evolutionary theorists have produced several plausible (if not
exactly proven) suggestions as to why strong jawlines and prominent brows are so
attractive in men, and small chins and high cheekbones such a boon to women. To
take just one example, strong jawlines are thought to result from an unusually
strong surge of testosterone during puberty. Why should that be attractive?
Because鈥攕o the argument runs鈥攐nly men with robust immune systems are
able to tolerate such a surge. A firm jawline, in other words, is an outward
sign of hidden biological fitness.

But apply such Darwinian thinking to the special attraction we supposedly
feel toward our lookalikes and you draw a blank. After all, genetic variety, not
sameness, is supposed to be the key to producing biologically fit
offspring鈥攈ence the well known hazards of inbreeding. So surely we should
be programmed to find opposite types attractive?

One possibility is that our fondness for people who look like us is not what
it seems. There are all sorts of reasons we might end up with someone like
ourselves that have little to do with biology. Marriages, for instance, usually
unite people of the same religion, educational background and socioeconomic
status. What鈥檚 more, to look for a mate is to enter a high-stakes marketplace in
which the safest tactic is to choose鈥攐r else settle for鈥攕omeone at
about the same level as you in the pecking order of attractiveness. Making a
play for someone way above or below ourselves in that hierarchy is bound to end
in tears. Perhaps the perceived similarity of couples is a reflection of just
that: people finding their level.

Perrett and his team doubt it. They say that couples tend to match on a wide
range of characteristics鈥攕uch as size, eye colour and strength鈥攖hat
are not universal currencies of attractiveness. In these cases we must be
choosing partners who look like ourselves . . . or members of our family.

It was this realisation that drew Perrett鈥檚 team into investigating whether
our parents鈥� looks might influence our choice of mate. To test the idea, the
researchers presented undergraduates with a computer-generated image of an
average face at different ages and asked them to rate it for attractiveness. The
results were striking. Although all students preferred younger faces to old,
those whose parents were older than 30 when they were born were significantly
more attracted to older faces than were students born to young parents. So it
seems the older your parents when you鈥檙e growing up, the more likely you are to
prefer older partners later in life.

That doesn鈥檛 prove people are responding to their parents鈥� looks. As well as
having more wrinkles, older parents are often wealthier and able to offer
greater stability. Perhaps that鈥檚 what makes older faces more alluring for the
children of older parents? It鈥檚 unlikely. In addition to rating faces, Perrett鈥檚
students were asked to give an age range for their 鈥渋deal partner鈥濃�攊n
other words the kind of person with whom they鈥檇 want to share their lives,
rather than just have sex. This was no higher than normal for those with older
parents, indicating they really were judging by looks in the earlier study and
not by the material resources that age represents.

By choosing to focus on age in their experiments, the researchers were
sidestepping another potential pitfall. Thanks to genes, we share many physical
features with our parents. So many, in fact, that it was always going to be hard
to know whether the students had learned what鈥檚 attractive by looking at their
parents, or at themselves in the mirror. That鈥檚 why the team chose age. Because
we can never be the same age as our parents, Perrett explains, 鈥渢here is no
chance of self-inspection affecting the choice鈥�.

That鈥檚 hardly the case with noses, chins and jawlines, which we may well have
inherited. So proving these exert the same sort of influence is more
complicated. Even so, Perrett鈥檚 colleague Tony Little is currently studying hair
and eye colour. 鈥淵ou need huge samples and complicated statistics to control for
the effect of self,鈥� he says, 鈥渂ut so far the results look promising.鈥� His
preliminary findings suggest we are most attracted to people with eyes the same
colour as those of our opposite-sex parent. A hint, perhaps, of a biological
basis for Freud鈥檚 Oedipus complex? 鈥淭he appearance of opposite-sex biases is
highly suggestive of Freudian patterns,鈥� says Perrett.

To settle the matter once and for all, you would have to compare the
preferences of people brought up by biological and adoptive parents. If Perrett
and his team are right, adopted children should show a preference for faces that
are similar to those of their adoptive parents, not their biological ones.
Although the team has no plans to test this at the moment, there is a second,
more distant line of reasoning they can draw on.

The idea that we learn what鈥檚 attractive from our parents when we are growing
up may seem radical to us, but it鈥檚 no revelation for biologists studying other
animals. From looking at their parents, many learn very early in life who they
should mate with later on. And they can be easily hoodwinked. A duck brought up
in a goose family will try to mate with geese when it reaches maturity. The
Javanese mannikin, normally a drab brown bird, can be fooled into preferring
mates with red crests simply by gluing red feathers onto its parents鈥� heads.

Even mammals have been shown to be in thrall to this 鈥渟exual imprinting鈥�. In
1998, a team led by Keith Kendrick of the Babraham Institute in Cambridge
persuaded ewes to adopt newborn goats, and nanny goats to adopt newborn lambs.
In adulthood, when they were led into a barn and given a choice between a sheep
and a goat of each sex, the fostered animals didn鈥檛 hesitate. 鈥淚t was clear very
quickly that cross-fostered animals chose to mate and socialise with their
[adopted] mother鈥檚 species,鈥� says Kendrick.

Of course, sexual imprinting in these animals is acting at a pretty crude
level鈥攖hey鈥檙e merely using their parents to decide which species to mate
with. As humans, we don鈥檛 need to examine our parents to learn to fancy people
rather than chimpanzees. So if sexual imprinting happens in people, it must have
a subtler role, skewing our choice of mate towards a parental 鈥渢ype鈥�.

Even if it does, though, this still doesn鈥檛 address the bigger mystery of
what purpose such fine-tuning of our beauty detectors might serve. Sexual
imprinting may explain how we learn to prefer faces that are similar to our own
or those of our parents. But why learn at all? What鈥檚 the reproductive
pay-off?

One possibility, according to Pat Bateson of the University of Cambridge, is
that inbreeding is not always such a bad thing. Mating with a relative, rather
than a complete stranger, traps harmful genetic traits in a population鈥檚 gene
pool. But at the same time, it might preserve combinations of genes that are
successfully adapted to your particular local environment
(快猫短视频, 26 January, p 13).
It might also increase the proportion of your genes that you
share with your children, making it even more worth your while鈥攆rom the
standpoint of your selfish genes鈥攖o invest time looking after them.

That鈥檚 why Bateson believes there鈥檚 a balance to be struck between reckless
outbreeding and obsessive inbreeding. And in animals at least, he believes this
is achieved by sexual imprinting. It鈥檚 a precise mechanism for improving the
quality of offspring, he says.

In the early 1980s, Bateson showed that Japanese quails brought up in foster
families with artificial adornments like spots painted on their chests would
later choose mates with similar, but not exactly the same adornments. In fact,
the degree of similarity most preferred was one that would be found between
first cousins. In the light of these results, it鈥檚 perhaps no surprise that
marriages between first cousins are not just allowed but encouraged in many
human cultures.

Not everyone goes along with the idea that a bit of inbreeding is a good
thing. Bill Amos, also at Cambridge University, has recently shown that in
albatrosses, pilot whales and seals, outbreeding is always better. In these
creatures, the offspring of less closely related parents are always more fertile
and hence biologically fitter. In Amos鈥檚 view, a complete stranger is always
best. So how does he explain our attraction to people who look like us?

It all depends on the dangers of inbreeding in a given population, he says,
and the hazards are greater for animals like whales than people. 鈥淚n our
exponentially expanding global population, the effects of inbreeding are
minimised,鈥� he says. 鈥淭he desire for someone who looks like your father becomes
a good strategy because if you have reached the stage of choosing a mate, your
father was obviously good at producing young.鈥�

The twist, adds Amos, is that the degree of outbreeding in the population as
a whole that will make this a safe option hasn鈥檛 always been there, and still
isn鈥檛 in some parts of the world. 鈥淚 suspect you wouldn鈥檛 find this effect if
you went to small hunter-gatherer tribes in Africa.鈥�

For the rest of us, however鈥攊n our highly mobile, ethnically diverse
world鈥攖he risks of inbreeding may be less important. In fact, selecting a
strange mate from such a bewilderingly diverse market could pose greater genetic
and social dangers. Whether these are big enough to make us unconsciously prefer
parental lookalikes remains to be seen. But if they are, then unprepossessing
people everywhere can draw some comfort from the idea.

After all, why worry if you lack the perfect Brando jawline when there鈥檚 an
alternative route to someone鈥檚 heart. Simply make yourself look like
them鈥攐r better still, like their mum or dad.