Orangutans can make two separate sounds at the same time, much like songbirds or human beatboxers, a new study suggests.
University of Warwick researchers say the findings provide clues around the evolution of human speech, as well as human beatboxing.
According to the findings, male orangutans produce noises known as chomps, together with grumbles, while females produce kiss squeak sounds at the same time as rolling calls.
Dr Adriano Lameira, associate professor of psychology at the University of Warwick, said: “Humans use the lips, tongue and jaw to make the unvoiced sounds of consonants, while activating the vocal folds in the larynx with exhaled air to make the voiced, open sounds of vowels.
“Orangutans are also capable of producing both types of sounds – and both at once.
“For example, large male orangutans in Borneo will produce noises known as chomps in combination with grumbles in combative situations.
“Female orangutans in Sumatra produce kiss squeaks at the same time as rolling calls to alert others of a possible predator threat.
“The fact that two separate populations of orangutans were observed making two calls simultaneously is proof that this is a biological phenomenon.”
The researchers observed two populations of vocalising orangutans in Borneo and Sumatra across a total of 3,800 hours.
They found that primates within both groups used the same vocal phenomenon.
Co-author and independent researcher Madeleine Hardus said: “Humans rarely produce voiced and voiceless noises simultaneously.
“The exception is beatboxing, a skilled vocal performance which mimics the complex beats of hip hop music.
“But the very fact that humans are anatomically able to beatbox, raises questions about where that ability came from.
“We know now the answer could lie within the evolution of our ancestors.”
According to the researchers, the vocal control and co-ordination abilities of wild great apes have been underestimated compared to the focus on the vocal abilities of birds.
Dr Hardus added: “Producing two sounds, exactly how birds produce song, resembles spoken language but bird anatomy has no similarity to our own so it is difficult to make links between birdsong and spoken human language.”
Dr Lameira said: “Now that we know this vocal ability is part of the great ape repertoire, we can’t ignore the evolutionary links.
“It could be possible that early human language resembled something that sounded more like beatboxing, before evolution organised language into the consonant–vowel structure that we know today.”
The findings are published in the PNAS Nexus journal.
