Orangutan’s Vocabularies Are Shaped by Socializing With Others, Just Like Humans

A new study reveals apes have distinct and flexible ‘vocal personalities,’ opposed to a fixed repertoire of calls

A female Bornean orangutan with shaggy red hair carrying her son on her back
A female Bornean orangutan carrying her son in Central Kalimantan, Borneo, Indonesia. Anup Shah via Getty Images

Depending on different social situations, humans will tailor their communication to suit specific interactions—whether in a group of close friends or among strangers. Now, new research suggests social influences may be transforming the “vocabularies” of orangutans, too. In some cases, it takes just a single social interaction to shape these animals’ distinct “vocal personalities,” Rachael Funnell reports for IFL Science.

In a paper published by Nature Ecology and Evolution, researchers from the University of Warwick closely studied the “kiss-squeak” alarm calls of wild orangutans living in Borneo and Sumatra. The scientists recorded thousands of hours of vocalizations of 70 apes across six different social groups between 2005 and 2010, which the team then analyzed.

Their collection of vocalizations revealed that dense orangutan populations had greater diversity and experimentation in their vocabulary. In these high-density populations, the orangutans tried out lots of new sounds by varying calls in pitch and duration. Smaller populations of orangutans, which were more spread out in the forest, opted for a shorter repertoire of tried-and-true calls.

Smaller, low-density communities “have a slang repertoire that they constantly revisit and use,” says Adriano Lameira, first author of the paper and a University of Warwick psychologist, to the Guardians Nicola Davis. In larger groups, “communication is more like a cacophony. It seems ‘novelty’ is at a premium, much like in songbirds, and that individuals want to show off their coolness and how [much of a] rebel they are."

The researchers behind the work concluded that wild orangutans have distinct “vocal personalities” that can be shaped by a given social group, instead of a hardwired set of calls as was previously assumed, Tibi Puiu reports for ZME Science. The finding is a huge step forward in understanding the evolution of language, according to the study authors. 

“Great apes, both in the wild and captivity, are finally helping us to resolve one of the longest-standing puzzles in science—the origin and evolution of language,” Lameira says in a press release.

Lameira stresses the importance of protecting wildlife like orangutans, not only for the sake of the apes, but so that scientists are able to learn more about the evolutionary history of primates. The endangered red apes are facing sweeping habitat loss as their forest homes are cleared for animal agriculture, palm oil, illegal logging, and more.

“Many more clues await us in the lives of our closest living relatives, as long as we manage to guarantee their protection and their preservation in the wild,” Lameira says. “Each disappearing population will take with it unretrievable glimpses of the evolutionary history of our species.”