An orangutan has provided researchers with possible new insight into how human speech first evolved. By copying his trainers, Rocky the orangutan was able to emulate human speech by learning more than 500 new vowel-like sounds, something that researchers had previously thought was impossible for great apes to manage.
“Our latest findings open up the potential for us to learn more about the vocal capacities of early hominids that lived before the split between the orangutan and human lineages to see how the vocal system evolved towards full-blown speech in humans,” said Dr Adriano Lameira, from the University of Durham, in a statement. While Rocky cannot speak, he does demonstrate that apes are capable of a greater amount of control over their voices than previously thought possible.
The orangutan was able to copy the pitch and tone of sounds produced by the researchers, making vowel-like calls – something that is thought to have been critical for the development of language. When compared to a massive database of over 12,000 hours’ worth of wild orangutan calls, the scientists found no other noises like those produced by Rocky during his imitations, showing that he was able to learn new sounds.
This may not sound like much, but it is an important new discovery. “Instead of learning new sounds, it has been presumed that sounds made by great apes are driven by arousal over which they have no control, but our research proves that orangutans have the potential capacity to control the action of their voices,” explained Dr Adriano Lameira, who co-authored the study published in Scientific Reports. This ability of what is known as “vocal fold control” is thought to have been critical in the evolution of language in our ancestors, but as it has never been seen before in apes, it was presumed to have developed after our lineage split off from our last common ape ancestor.
Yet this research now seems to cast doubt on that notion. As the paper concludes: “A non-human great ape can achieve levels of volitional voice control qualitatively comparable to those manifested in humans.” In fact, the researchers claim that the incredible degree to which Rocky is able to control his voice is a bit similar to how humans conduct a conversation. This is interesting, because previous research by Dr Lameira has shown how another captive orangutan was able to make sounds that had the same rhythm and pitch as human speech.
So it seems that perhaps the ability to produce speech was not something unique to our own lineage, but was possible even before orangutans had split on the evolutionary tree.