Gibbon Communication Gets Decoded

If you were to hear the "hoo hoos" of gibbons chattering and calling away in the wild or even zoos, do you think you could translate it? Probably not, but a team of researchers think they are very close to decoding the secrets of gibbon 'talk,' taking them a step closer to understanding language development in primates.

Nature World News previously reported how researchers investigating primate song looked to silvery gibbons - iconic singers among the primate family - for clues as to how human language arose. They determined that animals like gibbons use various songs to imply new things, like danger or the presence of food. However, it's a sense of melody - likely learned from bird song - that could have given human ancestors the inspiration to turn their calls into something more complex. This, they argue, served as a foundation for complex sentence structure.

However, gibbons don't just sing. A study recently published in the journal BMC Evolutionary Biology details how lar gibbons (Hylobates lar) produce soft "hoo" sounds that are unique from the loud and conspicuous songs that experts are familiar with.

"These animals are extraordinarily vocal creatures and give us the rare opportunity to study the evolution of complex vocal communication in a non-human primate," study author Esther Clarke said in an emailed statement. "In the future, gibbon vocalizations may reveal much about the processes that shape vocal communication, and because they are an ape species, they may be one of our best hopes at tracing the evolution of human communication."

According to the study, Clarke and his colleagues spent nearly four months observing wild lar gibbon communities in the forests of Northeastern Thailand. They recorded over 450 hoo sounds in all, and noted what was occurring when each was sounded.

In some cases, they even purposely elicited responses by realistically simulating the calls of various predators, such as birds of prey or leopards.

They quickly found that the hoos often varied acoustically to ensure that the predator in question couldn't hear. For instance, hoos for when a raptor was nearby were short and repeated quickly under a 1kHz threshold. Most birds of prey hear best between 1 and 4kHz.

In social situations, it was found that males were the dominant hoo-ers, while females chose to remain quiet during neighborly encounters. Pitch, it was found, varied even then and likely carries key meaning.

It's important to note that the implications of these observations remain unclear, but the researchers are excited to see where their growing understanding will take them.

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