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Speciesism - Index
Looking for Personality in Animals, of All
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
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
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
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.