Humans have a unique capacity for speech that far exceeds any other living thing. However, researchers have now discovered that great apes are actually not as far behind as once believed! Adriano R. Lameira and his colleague Robert Shumaker used a membranophone (the novelty instrument known as a Kazoo) to show how orangutans have the ability of active voicing. The kazoo can only produce the buzzing sound if the player does so at will. That ability to choose vocalization was key in us (humans) ever developing the ability to speak in the first place.
Voice control is the most important and necessary tool for speech. It’s what separates us from all other species, giving us the gift of speech – the defining mark of humanity. Voice control is the uniquely advanced ability to engage our vocal cords to produce sound at will. Without voice control, there are only reflexive screams and cries – the sounds other animals produce as automatic responses to changes in the environment and physiology.
This one tool has made all the difference in the world. It has served as the interface of our social and societal relationships, enabling us to pass information on from one generation to the next, feeding into a growing body of knowledge that has made us so evolved. However, why our species alone has developed such a powerful method of communication remains unclear.
We may be the most advanced in communication for unknown reasons, but scientists were misguided when they thought that the capacity of great apes to control their voice was just as limited as that of their fellow mammals. Recently, it has come to light that great apes can mimic the rhythm of speech, producing babbling vocalizations (see video below). This wouldn’t be possible if great apes could not deploy and use their voice on command in similar ways to us.
Lameira and Shumaker wanted to find out more about these abilities, so they gave captive orangutans at the Indianapolis Zoo the opportunity to play the kazoo. What’s special about this instrument is that merely blowing a constant stream of air into it produces no sound. The player has to hum or talk into the kazoo to activate the instrument. What makes the membrane of the instrument vibrate and the instrument play is the bursts of air produced by our vocal folds opening and closing when we vocalize.
Some of the orangutans in their study activated the kazoo within minutes. They were able to produce sounds of varying pitches and durations in response to kazoo demonstrations by the human experimenters. The speed with which these orangutans changed the quality of their voices shows that they were producing the sounds at will – not through training, which would have required months of reflex building and conditioning. The research has been published in Nature.
Not all orangutans managed to play the kazoo. Some had a greater capacity and/or motivation to demonstrate vocal control than others. The will to perform differed between individuals, so one great ape can never be representative of the vocal abilities of a whole species. Further research and testing should be tailored to match each individual ape’s limitations and drive for accuracy. The same applies to people as any teacher or linguistic therapist can vouch that children develop speech at different rates and manners despite sharing virtually the same environment.
These tests were conducted in controlled settings with voluntary participation from captive individuals. Although there is evidence of wild orangutans that suggests they also use vocal control in their natural environment to communicate and pass information between individuals and generations.
As reported by The Conversation:
“Wild orangutans can modify their alarm calls with hands and leaves to make them sound bigger, depending on how dangerous the predator they encounter is. Wild chimpanzees are more likely to produce snake alarm calls when group members are unaware of the threat, and selectively inform high-ranking group members that food is available – both indicators of intentional control of vocalizations.
Wild orangutan mothers delay alarm calls in response to predators until there is no danger, before then informing their infants of the danger that just passed through the forest floor below. Such an ability not only indicates some degree of vocal control, but also another key prerequisite for speech – the ability to communicate about the past.
They are truly fascinating and intelligent creatures, and we must make every effort to conserve and protect them and their habitat – not just to understand better our place in the natural world, but as a mark of respect for theirs.”
Clues to how and when the various skills required for full-blown speech emerged in our evolutionary lineage may lie in the understanding of great apes’ speaking abilities. The ultimate question that remains to be answered is, “why our species used the last few million years to hone these neural capabilities, but our close cousins didn’t – or weren’t able to.”
