Scientists Discover Driving Force in the Evolution of Speech

Why do we talk the way we do? It might trace back to when our ancient ancestors left the jungle for the open savanna.

Somewhere between 5.3 million and 16 million years ago, Africa's landscapes transformed from thick, leafy forests to wide-open grasslands. This environmental shift forced our ancestors out of the trees and onto the ground. Along with all of the physical and behavioral changes this may have caused, researchers also believe it may have changed the way we speak for good.

"Open landscapes such as the savanna provide us with fewer physical obstructions to negatively impact signal transmissions, meaning our voices can travel further as opposed to in dense forests," Charlotte Gannon, a researcher at the University of Warwick in the United Kingdom who studies language evolution, told Newsweek. "The shift to these open spaces, and fewer obstructions, may have increased [the] reliability of our communication."

But what exactly does this mean in practice?

By analyzing the vocal calls of our living relatives—the orangutan—Gannon and her team at the University of Warwick and Durham University were able to establish how different calls could travel across different landscapes.

Person speaking
Stock image of a person speaking. Human speech may have evolved partly due to our environment and the changing landscape of the African savanna. AntonioMari/Getty

In their study, published in the journal Nature Scientific Reports, the team played 487 calls from both Sumatran and Bornean orangutans and measured their audibility at set distance intervals over an overall distance of over 1,300 feet in the South African savanna.

"In our study, in particular, we found that in these ecological settings, consonant-like calls traveled a lot further than vowel-like calls," Gannon said.

Indeed, around 80 percent of consonant-based calls were audible at 1,300 feet, compared to only 20 percent of vowel-based calls.

"[Our results] were surprising," Gannon said. "The law of sound propagation for pure tones would predict that lower-frequency sounds (aka the grumphs/proto-vowels in our study) would have traveled further than higher-frequency sounds (aka the kiss squeaks/proto-consonants). Our results actually found the opposite to this: the kiss squeaks traveled further than the grumphs."

Gannon said these results highlight the importance of studying living apes to learn about our species' story.

"We can view them as time machines that allow us to re-create key moments of our history so we can learn more about the evolution of our language," she said. "Despite their prevalence in modern languages, consonants have often been forgotten when discussing speech evolution. Our research highlights not only their presence in ancient times but their importance to our story and development of language."

Do you have an animal or nature story to share with Newsweek? Do you have a question about human evolution? Let us know via nature@newsweek.com.

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About the writer


Pandora Dewan is a Senior Science Reporter at Newsweek based in London, UK. Her focus is reporting on science, health ... Read more

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