Today’s interesting press release from the University of St Andrews calls attention to a paper on the singing behavior of gibbons as a mechanism to ward off predators in addition to mating practices. Esther Clarke, Klaus Zuberbuhler, both of the University of St Andrews and Ulrich Reichard, of the Max Planck Institute observed the singing behavior of white-handed gibbons in Khao Yai National Park, Thailand. The experimenters said:

“We are interested in gibbon songs because, apart from human speech, these vocalizations provide a remarkable case of acoustic sophistication and versatility in primate communication. Our study has demonstrated that gibbons not only use unique songs as a response to predators, but that fellow gibbons understand them.

This work is a really good indicator that non-human primates are able to use combinations of calls given in other contexts to relay new, and in this case, potentially life-saving information to one another. This type of referential communication is commonplace in human language, but has yet to be widely demonstrated in some of our closest living relatives – the apes.

Not unlike humans, gibbons assemble a finite number of call units into more complex structures to convey different messages, and our data show that distant individuals are able to distinguish between different song types and understand what they mean. This study offers the first evidence of a functionally referential communication system in a free-ranging ape species.

Finding this ability among ape species, especially gibbons who in a sense bridge the evolutionary gap between great apes and monkeys, could shed light on when this ability developed in the primate lineage.”

Here’s the paper.