Washington, Dec 11: Monkeys have the vocal tracts to produce human speech sounds, but what they lack is a speech-ready brain, a new study has found. The study, conducted by researchers from the US and Europe and published this week in the US jourl Science Advances, used X-ray video to see within the mouth and throat of macaque monkeys induced to vocalise, eat food or make facial expressions, Xinhua news agency reported.
The scientists then used these data to build a computer model of a monkey vocal tract, allowing them to answer the question “what would monkey speech sound like, if a human brain were in control?” The results showed that monkeys could easily produce many different sounds, enough to produce thousands of distinct words.
For example, monkeys could produce comprehensible vowel sounds — and even full sentences — with their vocal tracts if they had the neural ability to speak.
However, the researchers noted that while monkeys would be understandable to the human ear, they would not sound precisely like humans.
Therefore, the researchers concluded that previous research — largely based on plaster casts made from the vocal tracts of a monkey cadaver — underestimates primate vocal abilities and that evolution of human speech capabilities required neural changes rather than an adaptation of vocal atomy.
“Now nobody can say that it’s something about the vocal atomy that keeps monkeys from being able to speak — it has to be something in the brain,” said Asif Ghazanfar, Professor of psychology at the Princeton University and one of the study leaders.” (IANS)