Public Release: 

Can chimpanzee vocalizations reveal the origins of human language?

While closely related to humans, researchers discover that chimpanzees' vocalizations resemble human language less than you'd expect

Acoustical Society of America

WASHINGTON, D.C., May 8, 2018 -- It's very difficult to determine when, how and why human language began. While fossil primates provide important clues about human evolution, the sounds they made and the soft tissue involved in making those sounds weren't preserved.

But chimpanzees -- one of our closest living relatives -- provide important points of comparison for inferring the sorts of sounds our early ancestors may have made. During the 175th Meeting of the Acoustical Society of America, being held May 7-11, 2018, in Minneapolis, Minnesota, Michael Wilson, an associate professor at the University of Minnesota, will present his group's work searching for similarities between the vocal communications of chimpanzees and humans.

"Chimpanzees give a range of different calls: hoots, pant-hoots, pant-grunts, pant-barks, rough-grunts, nest-grunts, alarm barks, waa-barks, wraas, screams, copulation screams, and soft panting play sounds (a.k.a. laughter)," Wilson said. "Many of these calls grade into one another, and it can be difficult to categorize particular examples of some calls."

Wilson's group works with new and archival recordings of chimpanzees from Gombe National Park in Tanzania, the site where Jane Goodall, renowned primatologist and anthropologist, began the first long-term field study of chimpanzees.

"When Jane gives public talks, she often begins by giving a pant-hoot: a loud call that begins with an introduction, followed by a build-up, a climax and a let-down. Much of the work on chimpanzee vocalizations has focused on pant-hoots because they're loud, conspicuous, and seem to be important," Wilson said.

For their work, Wilson's group records calls from chimpanzees at Gombe using hand-held directional microphones and digital recorders. And, until recently, they applied simple statistical models -- such as principal components analysis -- to small sets of features like the duration of different call components, fundamental frequency, and frequency range. "More recently, my student Nisarg Desai has adapted techniques from speech technology, such as machine learning models, to better categorize calls," Wilson said.

Chimpanzee vocal communication is also interesting because it "raises questions about the evolution of signaling and social behavior," Wilson said. "Do chimpanzee pant-hoots inform other chimpanzees about good food patches, signal community membership, or individual identity, body size, or health?"

The group's findings so far suggest that chimpanzee vocalizations resemble human language less than you'd expect. For example, Wilson's student Lisa O'Bryan studied food-associated rough-grunt calls at Gombe and in a group of captive chimpanzees in Texas. "In contrast to some previous studies, which reported that rough-grunts vary acoustically in ways that could inform other chimpanzees about food quality, she found that within rough-grunt sequences to a given food type, chimpanzees produce a range of rough-grunt variants -- suggesting there is no consistent match between acoustic features and food quality," Wilson said.

And, it turns out, "chimpanzee vocal communication isn't particularly languagelike," Wilson said. "This is surprising, given that chimpanzees resemble us in so many other ways. But it seems that the key events in language evolution occurred well after the divergence of the chimpanzee and hominin (primate) lineages. In this case, language likely evolved due to uniquely human circumstances."

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Presentation 2aSC1 "Tracking chimpanzee pant-hoot changes across time and space" by Michael Wilson is at 8:45 a.m. CDT, May 8, 2018, in room Nicollet D1 at the Hyatt Regency Minneapolis.

MORE MEETING INFORMATION

The 175th Meeting of the Acoustical Society of America

The meeting is being held May 7-11, 2018, in Minneapolis, Minnesota.

USEFUL LINKS

Main meeting website: http://acousticalsociety.org/asa-meetings/

Technical program: http://acousticalsociety.org/program-of-175th-meeting-of-the-acoustical-society-of-america/

Meeting/Hotel site: http://acousticalsociety.org/asa-meetings/

Press Room: http://acoustics.org/world-wide-press-room/

WORLD WIDE PRESS ROOM

In the coming weeks, ASA's Worldwide Press Room will be updated with additional tips on dozens of newsworthy stories and with lay language papers, which are 300- to 500-word summaries of presentations written by scientists for a general audience and accompanied by photos, audio and video. You can visit the site during the meeting at http://acoustics.org/current-meeting/.

PRESS REGISTRATION

We will grant free registration to credentialed journalists and professional freelance journalists. If you are a reporter and would like to attend, contact Emilie Lorditch (elorditc@aip.org, 301-209-3029), who can also help with setting up interviews and obtaining images, sound clips or background information.

LIVE MEDIA WEBCAST

A press briefing featuring a selection of newsworthy research will be webcast live from the conference on Tuesday, May 8, 2018; register at http://aipwebcasting.com/webcast/registration/518asa.php to watch online. Topics and times to be announced.

ABOUT THE ACOUSTICAL SOCIETY OF AMERICA

The Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world's leading journal on acoustics), Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. For more information about ASA, visit our website at http://www.acousticalsociety.org.

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