Until now, it had been believed that non-human primates’ inability to learn to speak was due to limitations in their vocal anatomy (made up of the larynx, tongue, and lips) that prevented them from making sounds like those of human speech. A conclusion that had been reached based on experimenting with monkey corpses and plaster casts of their vocal tract.
An international team of researchers led by Tecumseh Fitch from the University of Vienna and Asif Ghazanfar from Princeton University have shown, by analyzing the movement of the vocal tract of live monkeys with X-rays, that their anatomy could easily produce an adequate range. of sounds to support spoken language. Something that shows that “previous techniques based on post-mortem samples drastically underestimated the vocal abilities of primates,” according to the study authors.
With the data obtained with the X-rays, at the VUB Artificial Intelligence Laboratory in Brussels, they managed to reconstruct a computer model of the vocal anatomy of these primates, which allowed them to answer the question “how would a monkey sound when talking, if a was controlled by a human brain? “ As you can hear in the video below, the monkeys could produce a wide variety of sounds, allowing them to pronounce thousands of different words.
So if these primates have what it takes to talk, why don’t they? It turns out that this discovery would imply that the evolution of human speech capabilities required neural changes rather than modifications of vocal anatomy. Thus, although monkeys have a vocal tract ready to speak, they lack a brain ready to control it.
“Now no one can say that vocal anatomy is what prevents monkeys from talking. It has to be something related to the brain.” That is to say, the macaques have the acoustic instrument perfectly created to emit words, but they do not know how to use it, their brain does not allow it ”, says Asif Ghazanfar in an interview with Nat Geo.
This research is much more important than you might think, since it tells us that an anatomy capable of speaking was present for a long time in the evolution of primates, something that can give us clues to discover how and when the human language. There is still a long way to go to discover exactly what role the human brain plays in speech. As Ghazanfar says in the same interview for Nat Geo, it is “now, the interesting question is: what is it about the human brain that makes it special?”
References:
Fitch, WT, de Boer, B., Mathur, N., & Ghazanfar, AA (2016). Monkey vocal tracts are speech-ready. Science Advances, 2 (12). https://doi.org/10.1126/sciadv.1600723
