Listen closely to those baboon calls — they may tell you a thing or two about human speech. Scientists who studied baboons’ wahoos, yaks, barks and other vocalizations have found evidence of five vowel-like sounds — a sign that the physical capacity for speech may have evolved over much longer timescales than previously thought.
“This theory has often been used to buttress the theoretical claim of a recent date for language origin, e.g. 70,000-100,000 years ago,” the study authors explained.
Scientists have begun to realize, thanks to computer modeling work, that the movement and control of the tongue’s position is actually much more important in making vowel sounds than the height of the larynx.
To test this idea, a French-led team of scientists studied vocalizations from 15 guinea baboons (12 female and three males) living in an outdoor enclosure at the National Center for Scientific Research’s primate center in Rousset-sur-Arc, France.
The scientists also verified that baboons really were physically capable of making these sounds by dissecting and analyzing the tongues of two baboons (both of whom had already died of natural causes that were unrelated to the study). For the ability to make specific vowel-like sounds, it seemed that tongue position really was more important than the larynx’s height.
Many scientists have thought that human speech may have evolved recently — within the last 100,000 years or so — partly because they figured that humans’ primate ancestors didn’t have vocal tracts that were capable of speech. But the new findings show that this assumption is not true: The ability to articulate vowel-like sounds, necessary for the development of human speech, was probably shared by the last common ancestor of humans and baboons 25 million years ago.