How Orang Utans communicate

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http://www.bioedonline.org/news/news.cfm?art=3494

August 2, 2007

Orang-utans are cunning communicators Apes modify their gestures depending

on human response

 

by Louis Buckley

news <http://www.nature.com/news>

 

 

 

When orang-utans want a human to hand over a tasty treat, they use a similar

strategy to that used in the game 'charades', say researchers. They repeat

signals that work, and modify those that don't, revealing surprisingly

sophisticated communication skills.

 

Non-verbal communication of this kind has already been seen in chimpanzees,

and there is plenty of anecdotal evidence that orang-utans are similarly

gifted.

 

" Talk to any zookeeper and they'll tell you they can communicate with the

orang-utans, and the orang-utans can communicate with them, " says Richard

Byrne of the University of St Andrews in Scotland. " But the big question is

whether the animal is communicating intentionally or simply responding to

learned symbols. "

 

Byrne and his colleague Erica Cartmill investigated the communicative powers

of six female orang-utans in British zoos. Each ape's keeper sat outside its

cage with two buckets containing food that was either desirable (such as

bananas) or undesirable (such as celery).

 

For 30 seconds, the orang-utan tried to express her preference, while the

keeper sat silently. The keeper then gave the ape the desirable food, half

the desirable food or all of the undesirable food, and waited silently for

another minute.

Discerning tastes

 

The three outcomes correspond to the experimenter's level of understanding —

full, partial or none — of the orang-utan's goal, says Byrne. " The

experimenter pretended not to understand what the animal wanted — something

a zookeeper would never normally do. "

 

All but one of the orang-utans stopped signalling when they were given all

the desirable food, and several retreated into their cages. " After they

received the desired food, most were busy eating, " says Byrne. " I don't know

what happened with that one individual, perhaps it was extremely greedy. "

 

When they were partially understood, the orang-utans repeated their previous

gestures in the hope of getting the rest of the desirable food. When given

undesirable food, they tried new gestures and stopped using those that had

apparently not been understood.

 

" The responses showed that the orang-utans had intended a particular result,

anticipated getting it and kept trying until it got it, " says Cartmill.

" They made a clear distinction between total misunderstanding and partial

misunderstanding. The result is that they are understood more quickly. "

 

" This is a tremendously exciting study, " says psychologist David Leavens of

the University of Sussex, UK. " It shows that orang-utans can communicate

with a human experimenter and make tactical decisions about how to

communicate. It's an unprecedented finding. "

 

The work may also contribute to our understanding of how human language

evolved, says Byrne. " There must have been a time when our ancestors had no

more language than chimps or orang-utans do today. By looking at

orang-utans, which communicate in quite a rich way but possess nothing like

the complexity of spoken language, we can look for clues about how human

ancestors may have behaved. "

 

 

1 Cartmill, E. A. & Byrne, R. W. Curr. Biol. 17, 1-4 (2007).