Orangutan "Kiss Squeaks" Are a First Step in Language Development

Story at-a-glance -

  • Orangutans use their hands to manipulate their voice in such a way that it sounds deeper and lower in pitch
  • The manipulated “kiss squeaks” sound very close to calls made by larger primates
  • Wild orangutans may “speak” with different dialects and possess the ability to invent arbitrary calls, which spread through social learning

By Dr. Becker

Orangutans are highly intelligent primates whose name means “person of the forest” in Malay.1 Indeed, they do resemble a very hairy person with especially long arms. A male orangutan’s arms may span seven feet from fingertip to fingertip, and nearly touch the ground when he’s standing.

Orangutans have a lot in common with humans, and they even appear able to modify sound, which is an essential tool for language development. In the video above, you can watch an orangutan making “kiss squeaks,” which appear as though she is blowing a kiss.

In reality, she has seen a human nearby and is using her hand to manipulate her voice, sounding an alarm call.

Orangutans Manipulate Their Voices to Scare Away Predators

Research published in The Journal of Experimental Biology found that orangutans use their hands to manipulate their voice in such a way that it sounds deeper and lower in pitch (similar to how your voice would sound if you spoke in a deeper-than-normal voice and cupped your hands around your mouth).2

The manipulated call sounds very close to calls made by larger primates, which suggests the orangutan wants to make it sound as though there are larger primates nearby to scare away threats. According to the study:3

Orangutans produce alarm calls called kiss-squeaks, which they sometimes modify by putting a hand in front of their mouth. Through theoretical models and observational evidence, we show that using the hand when making a kiss-squeak alters the acoustics of the production in such a way that more formants per kilohertz are produced.

… This increase is associated with larger animals, and thus using the hand in kiss-squeak production may be effective in exaggerating the size of the producer.

Using the hand appears to be a culturally learned behavior, and therefore orangutans may be able to associate the acoustic effect of using the hand with potentially more effective deterrence of predators.”

Orangutans Can Whistle

Along with creating “fake” deeper voices, some orangutans are known to whistle. There is even evidence of an orangutan spontaneously (without any training) acquiring a human whistle and modulating the duration and number of whistles to copy a human model.4

It’s also been found that wild orangutans may “speak” with different dialects and possess the ability to invent arbitrary calls, which spread through social learning.5 As for why primates don’t speak a language more similar to human speech, it’s thought they lack the laryngeal control required to produce learned voiced calls.6

However, they’re able to learn how to produce voiceless calls, i.e. whistles, with high levels of accuracy and control.7 This suggests orangutans possess some “important components of human speech learning and control,” according to research published in the Journal of the Acoustical Society of America.8

‘The Ape Who Went to College’


If you have any questions about whether orangutans possess the intelligence and capabilities to communicate like humans do, they will be put to rest if you watch the documentary “The Ape Who Went to College.” It tells the story of Chantek, a male orangutan who was taught sign language by University of Tennessee at Chattanooga (UTC) anthropology professor Lyn Miles.

It was the late 1970s when Chantek arrived at UTC. Just nine months old at the time, he was raised much like a human child, spending daily time with his handlers, and eventually learning sign language and developing the vocabulary of an 8-year-old child. He even had a word for ketchup (tomato toothpaste), which he reportedly like to eat with his cheeseburgers.9

After about a decade, university officials began to worry that Chantek could injure a student, so he was transferred to the Yerkes Primate Center in Atlanta. When Miles went to see him, he signed that he had hurt feelings. Years later, Chantek was moved again, this time to Zoo Atlanta.

Now in his mid-30s, he’s allowed to roam outdoors and has a mate, however Miles notes that he sees himself as “half human” and refers to the other orangutans as “orange dogs.” Miles told the Times Free Press:10

"When I show up, he signs to me that's he's crying because he wants to see me every day… He wants me to get the car and take him home to Chattanooga."

Orangutans Are an Endangered Species

Orangutans are unique creatures in so many ways. While males spend most of their time alone, mothers and their infants stay together for six or seven years (and females give birth only once every eight years). In captivity, the animals may live to be 60, although their average lifespan in the wild is closer to 30 to 40 years.

These primates spend most of their time (about 90 percent) in trees, even sleeping high up in the branches. Because they prefer so much time in trees, and are now found only in Sumatra and Borneo, logging in these areas has taken a toll on the species.

As a result of human activities like deforestation, the illegal pet trade and hunting, orangutans are now an endangered species.11 If changes aren’t made, it’s possible orangutans could become extinct in the wild in less than 25 years.12

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