Received: by alpheratz.cpm.aca.mmu.ac.uk id BAA08580 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Sat, 15 Apr 2000 01:15:40 +0100 Subject: Fwd: Monkeys Distinguish Different Languages Date: Fri, 14 Apr 2000 20:12:26 -0400 x-sender: wsmith1@camail2.harvard.edu x-mailer: Claris Emailer 2.0v3, Claritas Est Veritas From: "Wade T.Smith" <wade_smith@harvard.edu> To: "Memetics Discussion List" <memetics@mmu.ac.uk> Content-Type: text/plain; charset="iso-8859-1" Content-transfer-encoding: quoted-printable Message-ID: <20000415001226.AAA13196@camailp.harvard.edu@[205.240.180.114]> Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
Monkeys Distinguish Different Languages -- Itıs Not All Greek to Them
http://www.news.harvard.edu/gazette/2000/04.13/monkey.html
By William J. Cromie Gazette Staff
Monkeys can tell the difference between Dutch and Japanese as easily as
human infants, language researchers have found.
This ability makes humans less special than previously believed, and ties
our mental abilities more closely to our evolutionary kin.
"We donıt know yet what mechanisms in our brain allow us to discriminate
different languages, but we do know now that these mechanisms are not
unique to humans," says Marc Hauser, professor of psychology at Harvard
University. "I believe that we inherited an ability to process speech
from our primate ancestors (monkeys and apes)."
Working with collaborators at the Centre National de la Recherche
Scientifique in Paris, Hauser and his Harvard colleagues tested the
reactions of both cotton-top tamarin monkeys and French infants to the
different sounds of Dutch and Japanese languages. Both listened to
speakers of one language until they became bored. When the speakers
switched to a new language, babies instantly showed a shift in attention
by increasing the rate at which they sucked on pacifiers. Cotton-tops
quickly looked in the direction of the speakers.
Itıs not just the change in sound that attracts their attention. When the
sentences are played backward, neither responds. "Playing the languages
backward results in sounds that no vocal tract can produce," notes
Hauser. "Thereıs nothing to discriminate."
Both infants and monkeys sense a change in rhythm between the languages,
the researchers believe. "If youıre not a native speaker, rhythm is the
first thing that pops out at you about a language," Hauser explains.
"Dutch and Japanese have very different rhythms."
Jacques Mehler, one of the French scientists, had previously found that
infants discriminate between such rhythms. However, they donıt respond to
languages with similar rhythms such as Dutch, German, and English, or
French, Italian, and Spanish. The latest experiments show that the same
is true of monkeys and newborns 3 to 4 days old.
Aping Speech
The scientists describe their results in the Friday (April 14) issue of
the journal Science. Franck Ramus, from the Paris research center, is
lead author. "This is the first paper ever that directly compares the
response of humans and other animals to the same stimuli using the same
method," notes Hauser. "Itıs kind of revolutionary in that sense."
Previous experiments involved training the animals and used only short
segments of speech. This new technique cracks open the dam to a flood of
other tests of animal-versus-human speech perception. What kind of
abilities do chimps and other apes possess, since they are evolutionarily
closer to us than tamarin monkeys? How and when did speech perception
arise?
Brain mechanisms that allow us to perceive speech may not have evolved
for that specific purpose, but as a general ability for detecting sounds,
Hauser speculates. If so, it may go far back on the evolutionary road.
"Speech is a continuum of sound that we break up into categories," he
notes. "Even crickets, which evolved billions of years ago, possess an
ability to divide sounds into categories they avoid and categories they
approach. Birds also break up sounds into categories, particularly
songbirds. Looked at this way, itıs not so surprising that monkeys
perceive sound boundaries, and that these boundaries occur in the same
place in humans, their evolutionary cousins."
Nevertheless, the researchers did find subtle differences that may be
important. The babies heard two different speakers each say 10 sentences
in Dutch, then two others speakers voiced 20 sentences in Japanese.
Apparently, the variety of speakers, as opposed to changes in languages,
confused the infants.
The investigators then tested them with synthesized speech from which
they removed all speaker variations while precisely maintaining the
rhythm of the two languages. With the melody gone but the rhythm intact,
the infants responded as expected, sucking heartily to show they had
discriminated between the two languages.
Monkeys, on the other hand, hesitated more with synthesized than with
natural speech. "It may be that monkeys respond more to the greater
richness in natural speech," Hauser says. "When all the data are pooled,
however, these small differences do not alter our overall conclusion."
What occurs above and beyond such discrimination is a human brain that
can recombine the elements of speech into an infinite variety of
meaningful expressions. Can other animals do this? Hauser is not quick to
dismiss the idea.
In his latest book Wild Minds (published by Henry Holt), he argues that
just because animals canıt give voice to interesting thoughts, it doesnıt
mean that they donıt have them.
"The babbling of 1- to 2- month-old humans is similar to the sounds that
monkeys make," Hauser points out. "Itıs not until 3 to 4 months of age
that a human vocal tract develops its adult form, and we can give voice
to what we hear, see, and feel. Apes and monkeys have intricate family
and social lives, but they lack the physical ability to express the
richness of these relationships. That doesnıt mean they donıt have
thoughts that would interest us."
Copyright 2000 President and Fellows of Harvard College
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