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- Taco, a plump and aging Mexican chihuahua,
hops down from his favorite recliner. He waddles into the bedroom after
Marvin Pettet, who has just come home from work in Columbia, Tenn.
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- Pettet places his jacket on the bed,
but it slides over the edge onto the floor. Taco, who has been watching
closely with puffy black eyes, emits a little growl and trots quickly out
to the kitchen where Pettet's wife, Ava, is making dinner. Yip! Yip!
Yip!
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- "What's the matter Taco? Did Marvin
leave his clothes on the floor?"
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- Yip! Yip! Yip! Yip! Taco trots back to
the bedroom and barks until Marvin picks up the jacket up.
-
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- "He's telling on you, Marvin,"
Ava yells from the kitchen.
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- Marvin comes out of the bedroom with
Taco at his heels. "Oh don't be silly. He's just barking."
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- Ava argues that Taco communicates clearly
and often. Most pet owners have no doubt that their animals talk to them
and understand what they're told.
-
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- The questions that animal scientists
are trying to answer are much like the frequent debates between Marvin
and Ava over Taco: To what degree can we really talk to the animals? How
sophisticated is the level of communication among and between species?
-
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- The original movie Dr. Dolittle and the
current remake reveal a lot about our fantasies and the irresistible urge
to anthropomorphize. But fact is often stranger and usually much more interesting
than fiction. Dolittle aside, there is a solid base of research on animal
communication and cognition that suggests little Taco may actually know
what he is talking about.
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- A communications array
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- From honey bees to chihuahuas to elephants,
animals use a fantastic array of methods to sense the world around them,
to communicate with each other socially and to evade predators and hunt
prey. Humans may appear to be at the top of the communication tower, but
the rest of the animal kingdom possesses a range of senses that far exceeds
our own.
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- Bees that have been scouting for food
sources return to their hives and perform elaborate dances that describe
with vibrations the location and quality of a bed of flowers more than
10 miles away. Elephants that are separated by large distances emit sounds
below the level of human hearing telling each other of their locations
and warning fellow herd members of danger.
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- Most recently, scientists learned that
giraffes, long believed to be one of nature's most silent creatures, are
quite chatty at very low frequencies inaudible to humans.
-
-
- Is it also possible that wild animals
sometimes try to communicate with us? Naturalist Kady Payne, who discovered
that elephants communicate via low-frequency sounds, says it is possible.
Her new book Silent Thunder: In the Presence of Elephants, out in two weeks
from Simon and Schuster, describes her work in Africa.
-
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- Several years ago, Payne says, she and
collaborator Joyce Poole were recording certain low-frequency sounds made
by male elephants. They were driving their Jeep as close as possible to
individual males to provoke and record them. The scientists' methods caught
the attention of an old bull. Payne says the experience that followed left
her breathless and respectful.
-
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- "He immediately seemed to understand
what we were trying to do," Payne says. "He sauntered to the
vehicle, put one tusk inside and rumbled right into the microphone. Then
he carefully twisted his head and pulled out, went to the hood of the Jeep
and tapped three times on it with his tusk. Then he turned and walked away."
-
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- Payne says she believes the bull had
given her and Poole what they wanted, then issued a warning to go away.
-
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- "He could have crushed the Jeep
or turned us over, but he didn't. Why not?"
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- Changed beliefs
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- For most of the 20th century, scientists
have dismissed the possibility that animals communicate intelligently and
think logically about what they are saying.
-
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- But in 1946, Karl von Frisch announced
his findings that honeybees engage in their complex communicative dance.
Since then, scientists have discovered that honey bees indeed appear to
have evolved one of the most complex communication systems in nature. According
to James Gould in his review of honey bee science in The Animal Mind, bees
make movements called waggle runs, in which the dancer vibrates her body
from side to side to describe to other bees how far it is to the newly
discovered flowerbed.
-
-
- The landmark example that a higher species
uses a symbolic language was pioneered by Robert Seyfarth and Dorothy Cheney.
They proved that vervet monkeys in Amboseli National Park in Kenya use
different calls to warn each other about different kinds of predators.
-
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- The vervets have one call that means
"Leopard!", another for "Eagle!" and a third for "Snake!"
Seyfarth and Cheney studied vervets that were spread out in an area of
forest out of sight of each other, foraging for food. When a monkey gave
the leopard call, the others ran for the tops of the trees. The eagle call
made them run for the ground. The snake call made them stand and look around.
By recording the calls and playing them over speakers in the wild, the
scientists showed that the monkeys react the same way as they did to a
live call.
-
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- Harold Gouzoulous of the Yerkes Primate
Center in Atlanta found the same phenomenon occurs in various species of
macaques, and he studied how they engage in deception.
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- Primates all have hierarchies among males
and females. The males at the top get all the good food and the little
guys take the scraps. Every now and then, while the higher-ranking males
are feeding on a bunch of ripe fruit that has fallen to the ground, a clever
guy at the bottom of the ladder pulls a fast one.
-
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- "I have seen a low-ranking animal
suddenly produce an alarm call for a leopard," says Gouzoulous. "All
those high-ranking animals run for trees and what does alarm caller do?
It sits there stuffing its face. Now does he do it on purpose? Why don't
they do it more often?"
-
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- Gouzoulous followed up with more recent
studies at Yerkes showing that the monkeys quickly are on to the "boy
who cries wolf." Gouzoulous played the alarm calls of higher-ranking
monkeys to a group, observed their reactions, then played the alarm calls
of lower-ranking members to the group.
-
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- The group always reacted to the calls
of high-ranking monkeys, even though there was no evidence of danger. But
they quickly stopped reacting to the calls of lower-ranking monkeys once
they saw no evidence of danger to back up the calls.
-
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- "That requires a sophisticated level
of cognition," Gouzoulous says. "What they are saying in response
to these calls is that 'You are so and so at the top and have nothing to
gain by lying, while you are so and so and have much to gain.' "
-
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- Gouzoulous says that studying animal
communication provides "the window to the animal mind."
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- Using symbols
-
-
- One of the most remarkable examples of
animals talking to humans comes from the study of a bonobo chimpanzee named
Kanzi by Sue Savage-Rumbaugh and Duane Rumbaugh at the Yerkes Primate Center.
-
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- Kanzi has learned to achieve relatively
fluent two-way communication by learning symbols that are associated with
words and communicated via a keyboard.
-
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- Talbot J. Taylor, a human linguist at
the College of William and Mary, Williamsburg, Va., says he was one of
the most skeptical critics of Kanzi's ability to learn language and talk
to people.
-
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- "There are very few linguists who
were willing to believe that a non-human animal can learn that sort of
thing and I certainly started out as a skeptic," Taylor says.
-
-
- Tests of Kanzi's language abilities make
her equivalent to a 2 1/2-year-old child. Taylor says she can speak about
600 sentences. Taylor and several colleagues went to Yerkes to see for
themselves whether Kanzi was a circus act or a thinking animal.
-
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- "Kanzi was asked, 'Can you make
the toy dog bite the toy snake?" Taylor says. "He had variety
of animals in front of him. He then made the dog open his mouth and bite
the snake. That means he had to know the dog was the subject of the sentence
and the snake was the object, and that he wasn't the one to do the biting."
-
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- "What my colleagues and I find so
innovative about this work is that it's not just that these nonhuman primates
have been able to acquire the rudiments of English grammar, but they have
learned to use the language in very humanlike ways," he says
-
-
- Told about Kanzi, Ava Pettet says she
isn't surprised at all.
-
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- Says Ava: "I've always believed
that the animals can talk to us. It's just that people haven't been listening."
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