London: Researchers have shown that monkeys produce well differentiated proto-vowels, an advance that pushes back earlier estimates of when speech evolved in animals by about 2,00,000 years. The review study mentioned the theory of the “descended larynx”, according to which the larynx — commonly called the voice box — must be in a low position to produce differentiated vowels before speech can emerge.
According to the researchers, monkeys, which have a vocal tract anatomy similar to humans, had a higher larynx, and could not produce differentiated vocalisations. But based on the current study, they said, speech may have emerged 200,000 years earlier than previous estimates.
In 1969 in a long series of articles a US researcher, Philip Lieberman, proposed the theory of the descended larynx (TDL). Considering the acoustic cavities formed by the tongue, jaw, and lips, recent research showed the production of differentiated vocalizations is not a question of anatomy, but is related to the control of articulators.
But according to the current study, if the emergence of articulated speech is no longer dependent on the descent of the larynx — which took place about 200,000 years ago — scientists can now theorise much earlier speech emergence.
—PTI
