(JP) Monkey see, monkey do

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http://www.theage.com.au/news/Science/Monkey-see-monkey-do/2004/12/12/1102786949\

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Monkey see, monkey do

December 13, 2004

 

Before long, monkeys may be able to communicate with

humans, and their development could reveal how

language evolved. Laura Spinney reports.

 

In a laboratory in central Japan, monkeys are behaving

strangely. If someone sticks out a tongue, they do the

same. If a person goes to unclip the latch on a box,

the monkeys follow suit. If the monkeys need a rake to

reach a piece of fruit, they ask for it with a special

call. All of which is confounding experts, because

none of it should be possible. Monkeys in the wild

rarely ape, and as far as we know, they never, ever,

ask for rakes.

 

The Japanese macaques raised in Atsushi Iriki's lab

are not particularly gifted. But he expects them to be

communicating vocally with him soon, using simple

linguistic rules. This isn't just an elegant Dr

Dolittle curiosity: it holds the real possibility of

understanding autism in humans and unlocking the vast

unused power of the human brain.

 

Iriki, head of the laboratory for symbolic cognitive

development at the Riken Brain Science Institute, says

his experiment will tap into neural systems monkeys

always have had, but have never been activated. He

hopes to learn something about monkey thought, but

more dramatically, about how language emerged in

humans - and what happens when it breaks down.

 

As the ape brain evolved, it accumulated the

components of a language. By the time the vocal tract

could support speech, we were already human. But our

brains, according to Iriki, were " language-ready " much

earlier. In the monkey, this happened in a more

fragmented form. The only reason it did not emerge was

that the conditions were never right.

 

Iriki knew that monkeys would never be able to speak,

lacking as they do the necessary vocal apparatus, but

he became convinced he could exchange meaningful coos

and grunts with them. To do so, he would have to rear

monkeys in an environment which to communicate in this

way was in their interest.

 

" This is a guy who is on to a really exciting research

program, " says neuroscientist Michael Arbib of the

University of Southern California. Monkeys in the wild

produce a limited range of calls. But, says Arbib,

" the general consensus would be that the set of calls

is pretty much innate " .

 

" Iriki now seems to show that the call system may be

much more flexible than we thought. "

 

Iriki has a reputation for lateral thinking. Several

years ago, he showed that a macaque trained to use a

rake to grab a piece of fruit could operate just as

skilfully whether it could see its own hand, or was

prevented from seeing it and shown instead a video

image of the hand, rake and fruit reward.

 

Based on those findings, Iriki argued that monkeys had

a concept of body image that matched a nine-year-old

child. The findings seemed to demonstrate a level of

abstract thinking that nobody had suspected in

monkeys. And they created a dilemma for Iriki.

 

The problem was this: if monkeys have a relatively

advanced view of themselves, how is it that they

appear to be so oblivious to the behaviour of others,

unable to follow the gaze of another monkey or imitate

gestures, as human toddlers can do? It mattered to

Iriki because imitation and joint attention are

considered key building blocks of the kind of shared

understanding that makes communication possible. In

the wild, monkeys rarely imitate. But two pieces of

evidence suggested to Iriki that they could learn to.

They hinge on a recently discovered type of brain cell

called a " mirror neuron " .

 

Animal behaviour experts have very occasionally

observed both imitation and joint attention - which

lets one follow another's gaze - between mother and

infant macaques in the wild. And, though macaques seem

to show no interest in others' actions, activity in

their brains suggests they do. It harbours a type of

neuron that fires not only when it performs an action,

but also when it sees another monkey perform the same

action.

 

These mirror neurons were first identified by Giacomo

Rizzolatti of the University of Parma, Italy, and

colleagues, in the early 1990s, in an area of the

macaque brain called the premotor cortex. Luciano

Fadiga of the University of Ferrara then found

evidence that the human brain contained a mirror

system of its own.

 

When Rizzolatti's group investigated the human brain

more closely, they showed that, among other places,

mirror neurons show up in Broca's area, which, in the

human brain, is responsible for speech production.

 

There followed frenzied speculation about the role of

mirror neurons. Rizzolatti and Arbib claimed that by

providing the platform for imitation and shared

understanding, they made language possible.

Nevertheless, the question remained for Iriki: if

humans and monkeys have mirror neurons, why are humans

natural mimics while monkeys hardly ever imitate?

 

" Maybe monkey brains are unaware of the mirror

neurons' potential, " he says.

 

Iriki suspects that a likely trigger for the

realisation of the possible uses of this system was

human child-rearing practices. Using eye contact,

mothers teach their babies to look in the same

direction and to copy their actions. So, in Iriki's

lab, monkeys are reared as closely as possible to

humans.

 

In a study published last year, his group showed that

three in four monkeys brought up in this way learned

joint attention, and once they had learned it, began

to imitate a human's actions without having to be

taught.

 

When Iriki trained two macaques to use a rake to

retrieve a fruit reward, and then to call for either

food or the tool, he found the monkeys produced

different cooing noises depending on what they wanted.

" I think this is the evolutionary precursor of

naming, " he says.

 

Psychologist Klaus Zuberbuhler of the University of St

Andrews says that what Iriki reports is new: monkeys

are not known to produce acoustically distinct sounds

associated with novel events or objects - certainly

not with a man-made tool.

 

Iriki's monkeys' new calls do not yet have much

communicative power. Each monkey has a different call

for a given object, and the sounds are not the same.

Iriki thinks it might be possible to teach naive

monkeys to imitate the calls of others, and in so

doing, help them learn what they mean. They might then

use the calls themselves, to express the same idea.

 

" This is fascinating, " says Fadiga, who thinks Iriki's

work has the potential to reveal the origins of human

language. But he also has doubts, not least that the

monkeys will maintain any primitive language they

develop. " If they do not need it (language), they will

not teach others. "

 

Rizzolatti, meanwhile, is excited by the possibility

that monkeys have mirror neurons but are unable to use

them. " That has some interesting implications, " he

says. " For instance, perhaps autistic children have

the mirror system but cannot use it. Or perhaps it is

there, but not fully developed. "

 

Iriki does not think it too farfetched to suggest that

humans could one day tune into his monkeys' enriched

repertoire of sounds, using it to converse with them

at a simple level.

 

But if monkey brains have redundant capacity, why not

human brains?

 

" Human language and intelligence could be brought up

to a much higher level than we are at now, " he says.

 

" We are still in the middle of evolution. We can dream

of the future. "

 

- Guardian