The “kiss squeak” noises, which primates make to alert others, contain much more information than previously thought.
Previously, theories on speech evolution have focused on vowels. But the noise is a consonant-like sound, suggesting that human ancestors may have combined similar noises to make early syllables and words. Serge Wich, a professor at Liverpool John Moores University and the co-author of the study published in Nature Human Behaviour, told BBC Radio 4’s Today programme that the noises contain an “enormous” amount of information, from the gender of the orangutan to what kind of context it is made in.
The orangutans have also learnt to sometimes put leaves in or in front of their mouths to change the noise.
Prof Wich explained that the finding was interesting because researchers had previously assumed that that amount of information would not be available in a consonant. “We are very used to studying vowels in primates and those have been the building blocks of our theories in speech evolution,” he said.
“A lot of the vowel sounds are very common in a lot of primates and the consonant sounds seem to have less information in them so we just studied them less.”
He said that the new research showed the information in the consonant-like sounds were essentially the same as vowels.
He concluded: “It is likely that orangutans started to combine [the two] and maybe human ancestors combined those to repeat the same information… That might be the start of early syllables and words.”
- The Telegraph