Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer.
In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Nonhuman great apes have been claimed to be unable to learn human words due to a lack of the necessary neural circuitry. Our analyses demonstrate that chimpanzees are capable of syllabic production, achieving consonant-to-vowel phonetic contrasts via the simultaneous recruitment and coupling of voice, jaw and lips. Our findings demonstrate that in the absence of direct data-driven examination, great ape vocal production capacities have been underestimated.
Chimpanzees possess the neural building blocks necessary for speech. The ability to learn new vocalizations—known as vocal learning—is often assumed to have paved the way for spoken language in human evolution 1 , 2. It has long been claimed, however, that nonhuman primates are capable of vocal usage learning producing pre-existing calls in new contexts , but not vocal production learning modifying pre-existing signals, socially learning or imitating calls from other individuals 3 , 4 , 5 , 6 , 7 , 8.
It has also led to extrapolations that great apes lack key neural circuitry for voluntary motor control over the voice and articulators i.
Consequently, vocal production learning has been widely assumed to have emerged anew in the human lineage after it diverged from extant non-human great apes. Were such learned syllabic coupling to be demonstrated in a non-human great ape, it would set back origins of these abilities to an earlier stage of evolution. It is voiced, meaning that vocal cords vibrate actively during production phonation , and it is articulated bi-labially using both lips. These phenomena are readily observable in sound spectrograms because the relationship between speech articulation and speech acoustics is non-monotonic 25 ; for some regions in articulatory space, the resulting acoustic signal remains relatively stable as articulatory variables change.
