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Ape “vocabularies” are shaped by social interaction

A new study led by the University of Warwick has found that social mingling shapes and transforms the “vocabularies” of apes, just as it does in the case of humans. The scientists discovered that, as opposed to a fixed repertoire of instinctive, automated calls, wild orangutans show evidence of distinct “vocal personalities” that are molded by the social groups in which they live and communicate.

Living alongside orangutan communities in the low forests and swamps of Borneo and Sumatra in Southeast Asia, the researchers recorded the calls of around 70 individual apes across six populations. These populations differed naturally in density, ranging from groups that socialized intensely to more dispersed ones. 

In high-density populations, the apes communicated by using a large variety of original calls, continuously trying out many novel sound variants which were often modified or even discarded completely. 

By contrast, orangutans living in sparser, lower densities populations showed preference for more established, conventional calls. While these groups did not experiment with such a large number of novel sounds, when they did introduce new call variants, they tended to keep it, making their repertoire richer than that of apes living in high-density populations.

These results suggest that communication was also socially shaped in the case of our direct, extinct ape-like ancestors. This kind of social influence – though modest at first, before the rise of fully operational languages – could have then increased steadily, ultimately leading to the variety of ways in which human language is determined by those who surround us.

“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,” said study lead author Dr. Adriano Lameira, an assistant professor of Psychology at the University of Warwick. “We can now start conceiving of a gradual path that likely led to the rise of the talking ape, us, instead of having to attribute our unique verbal skills and advanced cognition to divine intervention or random genetic jackpot.”

“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. Each disappearing population will take with it unretrievable glimpses of the evolutionary history of our species,” Professor Lameira concluded.

The study is published in the journal Nature Ecology and Evolution.      

By Andrei Ionescu, Staff Writer

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