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Orangutans have the ability to produce vowel and consonant-like sounds similar to those of human speech. This is the finding of new research conducted by an international team of scientists, among them researchers from the University of Amsterdam's Institute for Biodiversity and Ecosystem Dynamics (IBED). The results, published in PLOS ONE scientific journal, may potentially offer a new point of departure for studying the evolution of speech.

Oerang-utan Tilda, IBED
Tilda. Photo: Zoo Köln

The world of science has to date been unable to discover the evolutionary development of human speech. Given that humans and anthropoids share a common ancestor, insight into the production and acquisition of sound by anthropoids may help obtain insight into the development of speech in human beings.

Similar rhythm

Adriano Lameira, a postdoctoral researcher at the IBED, and his fellow researchers distinguished and analysed two new sounds in an orangutan. These sounds have never previously been observed in orangutans either in the wild or in captivity. Orangutans produce sounds by quickly opening and closing their lips, similar to the way in which people do so when talking and in the same rhythm. One of the sounds produced shows similarities to consonants used in human speech and the other to vowel sounds.

Tilda makes consonant-like sounds (above) and vowel-like sounds (below). Videos: Adriano Lameira and Madeleine Hardus.

The observations were made while studying Tilda, an orangutan in Germany's Cologne Zoo. Tilda was born in Borneo and has been living in captivity since she was two years of age. The researchers gathered data in strict compliance with the guidelines and recommendations issued by Tilda's animal carer. 

Publication details

Adriano R. Lameira, Madeleine E. Hardus, Adrian M. Bartlett, Robert W. Shumaker, Serge A. Wich, Steph B.J. Menken: ‘Speech-like Rhythm in a Voiced and Voiceless Orangutan Call’, in: PLOS ONE (2015).