Vocal fold control beyond the species-specific repertoire in an orang-utan

Lameira, A.; Hardus, M.E.; Mielke, A.; Wich, S.A.; Shumaker, R.W.

Abstract

Vocal fold control was critical to the evolution of spoken language, much as it today allows us to learn vowel systems. It has, however, never been demonstrated directly in a non-human primate, leading to the suggestion that it evolved in the human lineage after divergence from great apes. Here, we provide the first evidence for real-time, dynamic and interactive vocal fold control in a great ape during an imitation “do-as-I-do” game with a human demonstrator. Notably, the orang- utan subject skilfully produced “wookies” – an idiosyncratic vocalization exhibiting a unique spectral profile among the orang-utan vocal repertoire. The subject instantaneously matched human-produced wookies as they were randomly modulated in pitch, adjusting his voice frequency up or down when the human demonstrator did so, readily generating distinct low vs. high frequency sub-variants. These sub-variants were significantly different from spontaneous ones (not produced in matching trials). Results indicate a latent capacity for vocal fold exercise in a great ape (i) in real-time, (ii) up and down the frequency spectrum, (iii) across a register range beyond the species-repertoire and, (iv) in a co-operative turn-taking social setup. Such ancestral capacity likely provided the neuro-behavioural basis of the more fine-tuned vocal fold control that is a human hallmark.

Citation

Lameira, A., Hardus, M., Mielke, A., Wich, S., & Shumaker, R. (2016). Vocal fold control beyond the species-specific repertoire in an orang-utan. Scientific Reports, 6, Article 30315. https://doi.org/10.1038/srep30315

• Journal Article Type: Article
• Acceptance Date: Jun 29, 2016
• Online Publication Date: Jul 27, 2016
• Publication Date: Jul 27, 2016
• Deposit Date: Jul 11, 2016
• Publicly Available Date: Jul 27, 2016
• Journal: Scientific Reports
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 6
• Article Number: 30315
• DOI: https://doi.org/10.1038/srep30315