Although monkeys are sociable, intelligent, and active, and capable of emitting several different types of sounds, they do not have the ability to produce speech, but what causes them to not make it?
No primate, however similar it may be to us, can do more than play loose sounds, and scientists think they know why. Emeritus professor Philip H. Lieberman of anthropology, cognition and linguistics at Brown University in Rhode Island, and colleagues conducted a study on rhesus monkeys between the 1960s and 1970s.
The study concluded that the monkeys had the supralarynggeal vocal tract absent, the region that the human have, that begins in the mouth, and follows the bump of the tongue to the throat. This means that even if a monkey had the right brain power to properly produce speech, the monkey’s vocal apparatus simply does not hold the ability to produce the sounds needed for speech.
In the study they analyzed the anatomical limits of the monkey to speech production, used the throat model of a monkey that had died from natural causes, and used a monkey under the effects of sedatives, in which they manipulated his tongue, analyzed and documented the positions that this could assume, and with this data, they estimated the scale of sounds that the monkey would be able to reproduce.
The documented scale was much lower than that found in humans, and has proven that monkeys would not have the ability to produce the sounds necessary to reproduce the E vowel, essential and common in most languages.
In the same study, the scientists analyzed x-ray videos of human children, and found that at birth, the position of the thong was similar to that of other primates at birth, but that with growth, it moves more to the back.
In a more recent study, a new team of scientists reproduced Lieberman’s study with state-of-the-art technology, and by analyzing x-ray videos of live monkeys as they produce sounds, they came to the conclusion that in reality, the scale of sounds they are capable of producing, is about 8 times higher than estimated in the previous study.
This proves that there is the physical capacity of monkeys to produce speech, and that the fact that this does not happen is more of a cognitive limitation than a physical limitation, and although according to the tests and simulations carried out the eventual speech of these being would be weak and limited, it would be physically possible.