(ORDO NEWS) — The way chimpanzees smack lips has a similar rhythm to human speech, and a new study suggests that this may be the key to how our ancestors learned the language.
The evolution of human speech is a mystery to scientists. In recent years, some of them have suggested that human speech comes not so much from vocalization as from the rhythmic movement of the lips.
No matter what language we speak, people all over the world open their mouths 2-7 times per second during a conversation (from 2 to 7 hertz), and each opening-closing cycle corresponds to a syllable.
But although universal rhythms of human speech or fast cycles of opening and closing the mouth were also found in the facial expressions of orangutans and macaques, a similar rhythm was first found in African chimpanzee monkeys.
Comparing records from four populations of chimpanzees, both wild and captive, researchers found that chimpanzees also bite their lips with an average speech rhythm of 4 hertz.
What this can tell us about our own history of evolution is limited, but given that this is one of the hallmarks of human speech, it can help us connect primitive vocals and human speech on an evolutionary timeline.
For example, a study published last year showed that when 2137 chimpanzee gestures were divided into groups and their duration was averaged, they obeyed some of the same basic mathematical principles as human speech.
The authors of a new study led by scientists from the University of St. Andrews in the UK, concluded that they “confirmed the hypothesis that speech arose from the ancient rhythmic signals of primates.”
Given their results, the team calls for future research among primates to find out how human speech rhythms arise in individuals and populations. Knowing this can tell us more about the evolution of our own language.
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