Macaques, a genus of primates found in Asian and Africa, have the physical capacity to speak in language, according to a study published today in Science Advances. Using X-rays, researchers were able to determine the range of motion of macaque vocal structures.
[Asif] Ghazanfar [a Princeton University professor of psychology] and co-corresponding author Tecumseh Fitch, a professor of cognitive biology at the University of Vienna in Austria, however, used X-ray videos to capture and then trace the movements of the different parts of a macaque's vocal anatomy--such as the tongue, lips and larynx--during a number of orofacial behaviors. These data were converted by coauthor Bart de Boer of the VUB Artificial Intelligence Laboratory in Belgium into a computer model that could predict and simulate a macaque's vocal range based on the physical attributes recorded by X-ray.
Using the computer model of the vocal tract, the researchers discovered that a macaque could, in theory, “produce comprehensible vowel sounds--and even full sentences--with its vocal tract if it had the neural ability to speak.”
But thank goodness they aren't chatty, because apparently they would sound absolutely terrifying. Here's the sound of a robotic macaque proposing marriage, which will surely haunt all of our dreams:
So why don’t monkeys talk? It’s likely not a limitation of the throat, but a limitation of the mind.
Macaques are an old genus whose vocal structures likely evolved a long time ago. For researchers studying human evolution, this suggests that proto-humans had a wide vocal range long before developing speech as we know it. If so, the key to language development could the combination of the ability to experiment with sound and a brain sophisticated enough to remember and interpret those sounds. Or, as the authors put it: "The findings suggest that human speech stems mainly from the unique evolution and construction of our brains, and is not linked to vocalization-related anatomical differences between humans and primates."
Should future macaques somehow gain that mental capacity, we can only imagine the kind of questions they'd ask.