title: Vocal fold control beyond the species-specific repertoire in an orang-utan.
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.
authors.affiliation: Evolutionary Anthropology Research Group, Department of Anthropology, Durham University, Dawson Building, South Road, Durham, DH1 3LE, UK.|Pongo Foundation, Papenhoeflaan 91, 3421XN Oudewater, the Netherlands.
authors.forename: Adriano R
authors.initials: AR
authors.lastname: Lameira
authors.affiliation: Independent researcher, Durham, DH1 5QU, UK.
authors.forename: Madeleine E
authors.initials: ME
authors.lastname: Hardus
authors.affiliation: Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Mielke
authors.affiliation: Research Centre in Evolutionary Anthropology, and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK.|Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Sciencepark 904, Amsterdam 1098, the Netherlands.
authors.forename: Serge A
authors.initials: SA
authors.lastname: Wich
authors.affiliation: Indianapolis Zoo, Indianapolis, IN 46222, USA.|Krasnow Institute for Advanced Studies, George Mason University, Fairfax, VA 22030, USA.|Anthropology Department, Indiana University, 107 S. Indiana Ave., Bloomington, IN 47405, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Shumaker
mesh_terms: D000818:Animals; D005075:Biological Evolution; D057079:Pongo / Q000235:genetics / Q000502:physiology*; D014827:Vocal Cords / Q000502:physiology*; D014828:Vocalization, Animal