Could This Be How Human Language Evolved?

October 20, 2015 | Kelly Tatera

Man in conversation gestures with hands
Photo credit: Heinrich-Böll-Stiftung/Flickr (CC BY-SA 2.0)

The evolution of human language has always been somewhat of a mystery, but psychologists speculate that our ancestors may have used “iconic gestures” to communicate.

Around the world, roughly 7,000 languages are spoken, and that pales in comparison to the number of languages that have been lost throughout time. Linguists estimate that in 8,000 BC, around 20,000 human languages existed. Even the 7,000 languages that exist today are disappearing— the Foundation for Endangered Languages estimates that at least 25 languages are lost each year.

The mystery of how language evolved to what it is today is still unsolved, but experimental psychologists conducted a recent study that led to a highly plausible theory. Marcus Perlman, a postdoctoral research associate at the University of Wisconsin-Madison, studies the creation and evolution of languages. He collaborated with some colleagues to run a series of experiments examining how effectively humans can communicate with each other vocally without using true speech.

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Imagine meeting someone for the first time and having to express yourself solely through gestures and random vocalizations. Before language evolved to the sophisticated form of communication we use today, that’s exactly what our ancestors had to deal with.

One method scientists have used to replicate how language evolved is through sign language. In instances where deaf children come together without a native signed language or in isolated communities that have a high rate of genetic deafness, scientists can watch how signed languages are created from scratch. They found that people communicate through “iconic gestures” — gestures that somehow depict their meanings. For instance, you’ve probably scribbled your signature in the air to ask a server for the bill at a restaurant, or waved your pointer finger back and forth to signal “No.” These gestures clearly communicate an idea without needing any vocalization at all. Essentially, “iconic” gestures signify something that is universally understood.

Man uses two fingers to indicate he wants to order two items
"Iconic" gestures can overcome language barriers. Photo credit: S. Krupp, Germany

Through time, iconic gestures can form a system of signs and linguistic rules of which members of a community share a uniform understanding. With this base knowledge, future generations can build on the language and evolve it “into a fully complex and expressive language,” according to Perlman. But the real challenge comes in when people have to create vocalizations that others will understand.

In the study, published in the journal Royal Society Open Science, the research participants obviously came into the lab already knowing a spoken language. But the researchers were able to learn a lot just by having people vocalize without speaking. By asking the participants to communicate with each other in a 10-round game of vocal charades, the scientists observed that the participants shared similar ideas about how voice properties like pitch, loudness, tone, and duration translated to specific meanings. For example, when asked to convey the word “fast,” participants did so by making high-pitched, loud sounds, somewhat mimicking the whistle-like sounds young boys make when playing with toy airplanes. This suggested that vocalizations, like gestures, can be universally-understood by depicting their meanings without spoken words.

“Thus, it appeared that participants were using iconic vocalizations to establish an initial understanding between each other, and then with repetition, they were turning these vocalizations into more efficient symbols — not unlike words,” noted Perlman.

The experiment highlights that when people need to communicate an idea, there are certain iconic gestures and vocalizations that seem to come naturally. Therefore, the evolution of language may very well have started out as a set of iconic communications before words evolved. Perlman says, “Even if language has multimodal origins, our study hints at the intriguing possibility that many of the spoken words of modern languages may have long ago been uttered by our ancestors as iconic vocalizations.”

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