Some animals have gained the ability to talk through learning or training, like parrots and elephants. But surprisingly, monkeys and apes, the human’s closest primate cousins, remain unable to produce human-like speech. Many believe that their anatomy hinders them from talking like humans, but new research has disproved that idea.
Despite being anatomically equipped for human-like speech, monkeys and apes, including the Japanese macaque, cannot talk like humans because of their lacking neural control over their vocal tract muscles.
Darwin’s Theory on the Topic
Some animals surprised us with their learned ability to talk, like Alex, the parrot, who had a vocabulary comprised of more than 100 words and even understood cardinal and ordinal numbers. In addition to that, an elephant named Kosik also learned Korean, using his trunk’s tip the same way people whistle with their fingers. Given these examples, some start to wonder, why don’t our closest primate cousins, monkeys and apes, know how to talk?
Many people initially assumed that monkeys couldn’t talk like humans because they were incapable of producing the speech sound of man. Most believed that the throats and mouths of these primates inhibit them from operating their tongue, cheeks, diaphragm, and vocal cords like us. But new research suggests otherwise.
Evolutionary Biologist and Cognitive Scientist William Tecumseh Sherman Fitch III, the lead author of the research, states that the answer to why monkeys and apes cannot speak like humans dates back to the period of Darwin. Darwin explained that nonhuman primates couldn’t produce human speech sounds due to their brain. As years passed, many experts argued that the anatomy of nonhuman primates hindered them from making the wide range of vowel sounds humans can make.
Fitch and Asif Ghazanfar, his co-author, a neuroscientist from Princeton University, theorized that Darwin was correct. And with that, they trained Emiliano, a long-tailed macaque, at the primate lab of Princeton. Emiliano sat on a chair as they took an x-ray video of him doing numerous tasks such as yawning, eating, and producing a variety of lip smacks and vocalizations. Their findings proved numerous anthropologists wrong. (Source: Science)
The Research That Disproved the Experts
The findings from their research suggest that macaques are anatomically-equipped to produce human-like speech. And as the macaque’s vocal anatomy resembles those of other apes and monkeys, Fitch states that these nonhuman pirates are also speech-ready.
The researchers formed this conclusion by analyzing 99 different configurations of Emiliano’s vocal tract, employing numerous linguistic tools capable of measuring which configurations of the larynx, tongue, and lip can make the frequencies corresponding to various vowel sounds. The experts then ran Emiliano’s vocal configurations into a computer program simulation, to which they found Emiliano’s simulated monkey voice to be clear and understandable.
If these nonhuman primates are speech-ready, why couldn’t they talk like humans? The answer lies in their brain. Monkeys and apes do not have neural control over their vocal tract muscles to operate them for human-like speech, limiting them to grunts, coos, and hoots. (Source: Science)