I want to say gibbons might be wrong so lets go with a monkey species instead. A lot of study was performed on this species and it was found they have different words for, eagle, snake, jaguar, other monkeys not from their group and a few others I can't recall from memory. In all they had at least 6 sounds that ment something specific. Possibly up to 15 or so actually sounds that meant something.
Incidentally, a recent article in
Nature showed that macaque monkeys have a homologue to our Broca's area.
Abstract.
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