Chimpanzees and humans are closely related, and consequently, researchers have long thought that there might be a connective link between chimpanzee vocalizations and human speech.

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Researchers from the University of Minnesota were captivated by this long-standing theory and decided to investigate more thoroughly. To do that, they recorded chimpanzee vocalizations with handheld microphones and digital recorders and compared them with archived chimpanzee vocalization records.

Unsurprisingly, decoding the cryptic vocalizations was no easy task.

"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)," explained associate professor Michael Wilson from the University of Minnesota.

"Many of these calls grade into one another, and it can be difficult to categorize particular examples of some calls."

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Chimpanzee vocalizations exhibit specific characteristics that can provide insight into their meanings; among those are factors such as vocalization duration and sound frequency. These are some of the things that the researchers paid particular attention to while performing their analysis.

The full results of the study have not been publicized just yet, but the team will announce their findings in their entirety during the 175th Meeting of the Acoustical Society of America in Minneapolis, Minnesota this week.

Nevertheless, all indicators suggest significantly more differences between chimpanzee vocalizations and human speech than initially thought. That said, the original theory that chimpanzee vocalizations paved the way for human speech may not hold any water.

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"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."

Related: Chimpanzees use hand gestures to convey distance with others

It should be interesting to see more details concerning the team’s findings. But for now, researchers will need to dig deeper if they wish to understand how our ancestors developed complex speech.

Source: Science Daily