Researchers have long used birdsong as a prime example when studying the complexities of speech. But a new study based on orangutans attempts to change that and shed some light on how humans acquired the ability to make more than one vocal sound at a time.
The researchers spent a massive amount of time observing and recording the great apes in the wild – some 3,800 hours in Borneo and Sumatra within range of the animals. What they found connects present-day beatboxing sounds to early human language.
Read More: How Closely Related Are Humans to Apes?
The Language of Orangutans
With the females, the researchers recorded “kiss squeaks,” or loud sounds the apes made as they pressed their lips together. The apes also made “rolling call” vocalizations, which they often did at the same time. That’s what the team was ultimately looking for, examples of “biphonic calls,” of which they recorded 293 from five different females. Orangutans use kiss-squeaks to ward off threats, and they sometime shake tree branches to emphasize their point.
With the male apes, the study recorded their “chomps” and “grumble” sounds, which sound like a car revving to start. On a frequency spectrogram, the researchers watched as the chomps, produced by the mouth, registered a high frequency, while the vocalized grumble produced by breath and vocal cords registered a low one. The grumble pattern carries on, repeating quickly, and can indicate annoyance or sometimes pleasure.
Biphonic Sounds and Human Language
Human speech works along similar lines, the researchers say, as we use the lips, tongue and jaw to make more subtle “unvoiced” consonant sounds. “Voiced” sounds come from the vocal cords, which we use to pronounce vowels. Meanwhile, certain human artists like beatboxers, combine these two abilities to mimic the sounds of hip hop in remarkably complex ways.
The researchers wonder if humans may have once used an ability similar to beatboxing in place of modern language.
“It could be possible that early human language resembled something that sounded more like beatboxing, before evolution organized language into the consonant-vowel structure that we know today,” says Adriano Lameira, an associate professor at the University of Warwick, in a press release.
This early language may have begun with one of our distant predecessors, a now-extinct hominid who had a special neurological aptitude.
“The very fact that humans are anatomically able to beatbox raises questions about where that ability came from,” he says. “We know now the answer could lie within the evolution of our ancestors.”