Looking
for Personality in Animals, of All People
By CARL ZIMMER
New York Times
March
1, 2005
A team of Dutch scientists is trying
to solve the mystery of personality.
Why are some individuals shy while others
are bold, for example? What roles do
genes and environment play in shaping
personalities? And most mysterious of
all, how did they evolve?
The
scientists are carrying out an ambitious
series of experiments to answer these
questions. They are studying thousands
of individuals, observing how they interact
with others, comparing their personalities
to their descendants' and analyzing
their DNA.
It
may come as a surprise that their subjects
have feathers. The scientists, based
at the Netherlands Institute of Ecology,
are investigating personalities of wild
birds.
Until
recently, most experts in personality
would have considered such a study as
nothing but foolish anthropomorphism.
"It's been looked at with suspicion
and contempt," said Dr. Samuel
Gosling, a psychologist at the University
of Texas.
But
scientists have found that in many species,
individual animals behave in consistently
different ways. They argue that these
differences meet the scientific definition
of personality.
If
they are right, then human personality
has deep evolutionary roots. "It's
a matter of degree, not of differences,"
said Dr. Piet Drent of the Netherlands
Institute of Ecology.
The
bird study that Dr. Drent and his colleagues
are conducting is considered the most
ambitious investigation of personality
in wild animals.
"They've
gone the furthest," said Dr. Sasha
Dall, an evolutionary biologist at the
University of Exeter in Cornwall.
The
Dutch researchers are studying the importance
of genes to the personalities of the
birds, and the effect different personalities
have on their survival. They hope next
to carry out parallel studies in humans
to see whether the same forces behind
the evolution of bird personalities
are at work in our own species.
The
science of human personality is about
a century old. Psychologists have relied
largely on questionnaires and other
testing methods to map out its dimensions.
One common method is for scientists
to ask their subjects how well certain
adjectives apply to themselves (or to
people they know well).
"Certain
traits tend to go together," Dr.
Gosling said. "We find that people
who are energetic also tend to be talkative.
It needn't be that way, but that's how
it tends to be." The flip side
is true as well: less energetic people
tend to be less talkative.
Psychologists
have found they can bundle these traits
into just a few personality dimensions.
People may be more or less extroverted,
for example, which means they are sociable,
assertive and tend to have positive
emotions. The same dimensions have been
documented across the world, from Zimbabwe
to the Russian Arctic, suggesting that
they are universal in humans.
Some
studies have suggested that genes are
responsible for some of the differences
in people's personality ratings. But
they have been far from conclusive because
scientists cannot do experiments with
humans. "Human mothers will not
let you just swap their infants at birth,
which would be a great study to do,"
Dr. Gosling said.
It
has been only in the last decade or
so that scientists have investigated
whether animals have personalities.
In one pioneering study in the mid-1990's,
Dr. Gosling studied a colony of 34 hyenas
at the University of California, Berkeley.
"My goal was simply to say, can
we measure personality in animals? It
wasn't clear it was going to work,"
he said.
Dr.
Gosling asked the four caretakers of
the colony to fill out a modified version
of the human questionnaire for each
animal.
"It
turned out that they agreed at the level
you find in humans," Dr. Gosling
said. What's more, the hyena personalities
fit some of the dimensions found in
humans, like neuroticism and agreeableness.
Since then, a number of other studies
have documented personalities in animals
ranging from chimpanzees to squid.
To
some biologists, the main question about
these animal personalities is why natural
selection keeps such a wide range of
them. "Why hasn't one personality
become the standard in the population?"
asked Dr. Drent. If being extroverted
offers the best odds for a hyena to
reproduce, you might expect that over
time, all hyenas would wind up as extroverts.
