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Gorillas don't ape each other - they know sign language from birth, say experts
http://www.dailymai l.co.uk/sciencet ech/article- 1139644/Gorillas -dont-ape- -know
-sign-language- birth-say- experts.html
By Claire Bates
09 February 2009
Gorillas are born with an international sign language of gestures that they
use to communicate.
The largest scientific study of the great apes revealed they had a
repertoire of 102 different signals - more than any other mammal.
Many of these such as 'disco arm shake' and 'tapping other' were common in
all the gorillas studied despite being in different continents.
The great apes can communicate with more than 100 hand gestures
The researchers from St Andrews University also found each gesture was
carried out with close attention to their audience: silent signals were only
given when other apes could see them.
Lead author Professor Byrne said: 'As we added more populations to the
study, most gestures that had seemed specific to one individual or one site
almost always turned up elsewhere.
'Any two populations are likely to differ a lot in the repertoire of
gestures shown, but all are drawn from a very large, species-wide 'pool' of
possible gestural signals.'
The team concluded that the gestures do not need to be learnt, because they
are already part of the natural gorilla communicative repertoire.
The new work throws light on a puzzle in the behaviour of great apes.
Several studies have found that apes are capable of the 'Do as I do' routine
that children also enjoy, but their copies of human actions modelled for
them are relatively inexact.
Professor Byrne explained, 'Dr Joanne Tanner and I studied a female gorilla
that was able to do this, and we found that all her 'copies' of apparently
novel human actions were really actions she'd done herself, sometimes years
before: they matched the demonstrated actions pretty well, but not exactly.
'It was only because of Tanner's long-term data on the gorillas that we
could find out what was going on.
'So we think that, just as in the case of communicative gestures, the fact
that apes have a huge repertoire of actions can explain how they imitate
human demonstrations and why their copies are usually inexact: they are
're-using' actions from their own repertoire, not learning new ones.'