For a long time, scientists believed that human speech evolved fairly recently, about 70,000 to 100,000 years ago. But a new study conducted in France shows that the evolution of spoken languages began as early as 25 million years ago. Findings of the study were published in the journal PLOS One.
Position of tongue more important than larynx height
Until now, it was believed that baboons lack the right kind of larynx, or voice box, to produce vowel-like sounds. The theorists claimed that human speech requires larynx to be placed lower in the neck. So, non-human primates with higher larynxes were unable to produce the vowel sounds universally found in human language. But researchers at the National Center for Scientific Research have found that primates like baboons can make vowel sounds despite their high larynx.
Studying the evolution of speech is one of the biggest challenges because spoken words leave no fossil records. Fortunately, scientists can study the physical structures such as the mouths of humans and their close relatives to understand the traits necessary for the emergence of speech. Dr. Louis-Jean Boë and his colleagues found in their study that the movement and control of the tongue’s position are far more important than the height of larynx in producing vowel sounds.
Formants give uniqueness to vowel sounds
French scientists studied the barks, wahoos, yaks, grunts, and other vocalizations of 12 female and three male guinea baboons over a period of one year. They analyzed a total of 1,335 spontaneous vocalizations looking for formants – the frequencies of sound that are unique characteristics of vowels. The distribution of formants is defined by the shape of our vocal tracts. Each vowel in human speech has a specific blend of formants that make it a unique, identifiable sound.
Scientists found that baboons make five distinct vowel sounds, pretty much like humans. Dr Louis-Jean Boë said in a statement that spoken languages evolved from “ancient articulatory skills” present in our last common ancestor with baboons 25 million years ago. The ability to create vowel sounds using the vocal tract became more sophisticated in the ancestors of modern humans over time.
The root of human speech
The latest study falsifies the long-held theory that speech and language emerged suddenly and simultaneously in modern Homo sapiens. Researchers dissected and analyzed the tongues of two baboons that had already died of natural causes to further verify that they were physically capable of producing vowel-like sounds. Tongue position was more important than the height of larynx, they said.
This study follows the findings of another study published in December that the macaque vocal tracts can produce the same vowel sounds as humans despite some structural differences. Both studies indicate that the root of human speech goes back to our common ancestor with monkeys.