Looking at primates in a zoo can sometimes feel like a two-way exhibit as these highly intelligent animals stare back at you, banana in your hand. It’s not surprising that captive animals like orangutans communicate with each other, but a new preprint (awaiting peer review) has revealed some interesting observations about orangutan gesturing. It seems that captive orangutans have adapted some unique actions as a means of communication, behaviors which don’t appear to exist in the wild. This could indicate that getting creative with gestures is an ancestral trait in great apes, potentially representing an important step in the evolution towards language.
Productivity in linguistics is the phrase used to describe what we’re doing when we come up with new expressions like flipping the bird, for example. It was an important development for humans in working towards our various languages, but it’s rarely seen in animals.
Of course, that’s not to say they don’t communicate. Experiments in the wild have shown how even across species some monkeys are capable of translating the warning calls of their canopy mates, but this sort of “talk” is usually prompted by the arrival of something threatening (a monkey-eating monitor lizard, for example) rather than just a casual chat. These life-preserving communication skills become established as natural selection favors the talkative.
To find out if primates are capable of productivity in linguistics, Marlen Fröhlich at the University of Zurich in Switzerland and colleagues turned to zoo orangutans to observe if and how communication between these animals differed from their wild counterparts.
While captivity isn’t the natural choice for orangutans, their situation does come with a few perks such as reliable food and zero risk of predation, loss of habitat, or being poached. With this in mind, studying their use of communicative tools is an interesting idea as the physical triggers for orangutan chat will be completely different. It could be that they spot their food arriving, or someone outside their enclosure is wearing a ridiculous hat. Furthermore, wild orangutans are quite solitary creatures while in zoos they’re forced to be in close proximity to each other, so opportunities for exchanging signals are far more frequent.
Fröhlich and colleagues looked at over 8,000 examples of non-vocal orangutan communications collated from 30 individuals across five zoos and 41 wild orangutans from forests in Borneo and Sumatra. By comparing the two, the team was able to single out behaviors that were exclusive to captive and wild animals.
Their results showed that captive orangutans practiced more gestures and facial expressions than wild animals, with several unique signals including raising an arm and repeatedly spitting water in the face of another animal. These actions seem to be motivated by play or food and would be repeated until the wanting orangutan got its way.
“We thus conclude that orangutans, when exposed to a more sociable and terrestrial lifestyle, have the behavioural plasticity to invent new communicative behaviours that are highly functionally specific,” wrote the authors of the paper. “This productive capacity by great apes is a major prerequisite for the evolution of language and seems to be ancestral in the hominid lineage.”
Of course, this study is yet to be peer-reviewed, which means its findings need to be replicated and further research carried out before they can be confirmed, but if any member of the animal kingdom is going to take the next step towards language it's orangutans.
[H/T: New Scientist]